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Self-reported lactose intolerance : subtitle an exploratory study of knowledge, attitudes, diagnostic… Lovelace, Heather Yvonne 2002

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SELF-REPORTED LACTOSE INTOLERANCE: A N E X P L O R A T O R Y STUDY OF K N O W L E D G E , ATTITUDES, DIAGNOSTIC CHARACTERISTICS A N D C A L C I U M INTAKE by HEATHER Y V O N N E L O V E L A C E B . H . E C , University of Manitoba, 1999 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE F A C U L T Y OF G R A D U A T E STUDIES (Human Nutrition Graduate Program) We accept this thesis as conforming to the required standards UNIVERSITY OF BRITISH COLUMBIA May, 2002 ©Heather Yvonne Lovelace, 2002 In present ing this thesis in partial fulf i lment of the requi rements for an advanced degree at the University of Brit ish Co lumbia , I agree that the Library shall make it freely avai lable for reference and study. I further ag ree that permiss ion for ex tens ive copy ing o f this thesis for scholar ly purposes m a y be granted by the head of my depar tment or by his or her representat ives. It is understood that copying or publ icat ion of this thesis for f inancial gain shall not be al lowed wi thout my wri t ten permiss ion. The Universi ty of Brit ish Co lumbia Vancouver , C a n a d a Date Abstract Numerous studies indicate that more people claim to be lactose intolerant than there actually are, which suggests widespread misconceptions exist. However, there has been little research to assess how people decide that they are lactose intolerant, and the nutritional implications of this perception. Perceived lactose intolerance may be just as important as true lactose intolerance since dietary changes may ensue, possibly compromising among other nutrients, calcium intake and increasing osteoporosis risk. The objective of this study was to assess calcium intake of individuals with self-reported lactose intolerance. Participants, recruited through newspaper advertisements, completed a food frequency questionnaire to estimate calcium intake from food and supplementary sources. Questions to elicit information on diagnosis, symptom severity, and demographics were included. Furthermore, knowledge, attitudes and dairy product intake behaviours were assessed using scales. A l l data were analyzed using the Statistical Package for the Social Sciences (SPSS, version 10) statistical environment, using descriptive statistics, chi-square or Fisher's Exact tests, t-tests and Analysis of Variance. A total of 159 participants completed and returned questionnaires (84% response rate). Respondents were 47 ± 15 yrs of age; 72% female and 28% male; 67% Caucasian; and >53.8% had self-diagnosed their lactose intolerance. Of those with physicians involved in diagnosis, 9.7% had confirmable diagnoses by reliable testing methods. Knowledge scores indicated good knowledge of lactose intolerance by participants. Attitudes towards dairy products were more negative among participants than among other British Columbians, and other Canadians when compared to population studies. Fluid milk caused discomfort in 67% of study participants. Mean estimated food calcium intake was 591 ± 382 mg/d. Estimates were lower for those who excluded milk, cheese or yogurt. There were no significant differences by sex or age, nor was there an age-by-sex interaction. Only 11.5% of participants met their age-appropriate Adequate Intake (AI) levels from food calcium sources alone. In comparison to large population studies (Alaimo et al., 1994) participants in this investigation had lower estimates of calcium intake from food sources alone. Thus, health professionals involved in diagnosis of lactose intolerance should be encouraged to discuss calcium needs, food sources of calcium and calcium supplementation with those self-reporting lactose intolerance to promote individuals' ability to meet AI levels. in Table of Contents Abstract ii Table of Contents iv List of Appendices vi List of Tables viii List of Figures xii Acknowledgements xiii Chapter I: Introduction/Rationale (Statement of the Research Problem) 1 Chapter II: Literature Review 5 Lactose Maldigestion and Lactose Intolerance 5 Prevalence of Lactose Maldigestion 7 Methods of Diagnosis • 7 Jejunal Biopsy 7 Lactose Tolerance Test 8 Breath Hydrogen Test 9 Clinical Symptom Evaluation 11 Fecal pH Analysis 12 Diagnosis by Complementary and Alternative Health Practitioners 13 Traditional Chinese Medicine 13 Naturopathic and Homeopathic Medicine 15 Association Between Lactose Maldigestion and the Experience of Symptoms 18 Dairy Product Consumption and Lactose Intolerance 22 Importance of Dairy Products 24 Adequate Intake Levels for Calcium 28 Food and Supplementary Calcium Intake 28 Attitudes 33 Information Sources 34 Methods in the Literature 40 Purpose 44 Chapter III: Methodology 45 Overview 45 Questionnaire Development 45 Instrument Description/Items Included 45 Demographics 45 Food Frequency Questionnaire and Calcium Supplementation 46 Vegetarianism 46 Diagnosis, Symptoms and Severity of Lactose Intolerance 46 Knowledge and Attitude Scales 47 Intake and Discomfort Scale 48 Information Sources and Learning Issues Surrounding Lactose Intolerance....49 iv Pre-Testing 49 Assessment of Reliability 50 Survey Administration 51 Subjects - Inclusion Criteria 51 Recruitment 51 Procedures 52 Data Management 54 Data Entry, Cleaning and Verification 54 Scale Construction 55 Data Analyses and Statistics 57 Frequency and Percent 57 Descriptive Statistics 57 Independent Samples T-Tests 57 Analysis of Variance (One-way, Multivariate) And Post-Hoc Analyses 57 X2 Analyses 60 Fisher's Exact Test 60 Correlations 62 Chapter IV: Results 63 Participants 63 Estimates of Calcium Intake 67 Estimates of Calcium Intake from Food Sources 67 Use of Calcium Fortified Beverages 70 Estimates of Calcium Intake from Calcium Supplements 71 Estimated Total Calcium Intake (Food and Supplementary Sources) 73 The Influence of Including or Excluding Milk on Calcium Intake 76 Vegetarianism 78 Vegetarianism and Calcium 78 Symptoms and Severity of Lactose Intolerance 80 Diagnosis 83 Knowledge 88 Attitudes 90 Age Comparisons 93 Gender Comparisons 93 Vegetarianism Comparisons 96 Education Comparisons 96 Dairy Product Intake and Discomfort 99 Information Sources 101 Information Needs 104 Chapter V : Discussion 106 Introduction 106 Recruitment and Study Focus 106 Age and Ethnicity 107 v Questionnaire Response Rate 107 Calcium Intake • 10 8 Estimated Calcium Intake and Calcium Intake in the Population 10 8 Adequate Intake Comparisons and Tolerable Upper Limits I l l Older Adults I l l --1 -1 A Calcium Intake and Ethnicity ' • Supplementation Practices , 115 Influence of Food Items on Calcium Intake 117 Use of Calcium Fortified Beverages 117 Other Calcium Containing Foods 118 Calcium Intake and Vegetarianism . 120 Diagnosis : 121 Contraindications to the Use of Valid Diagnostic Tools 122 Symptoms and Diagnosis 123 Implications of Diagnosis 124 Attitude |27_ Attitude by Vegetarian Status • Information Sources 129 Information Needs 132 Limitations 134 Study Design 134 Sampling 134 Location of Study 135 Vitamin D Assessment 137 Interpretation of Questionnaire Items 137 Lack of Valid Testing 138 Variable N for Analyses 138 Implications for Professional Practice 139 Future Research • • Assessment of Calcium Supplement Intake - • J ^ l Education 142 Chapter VI: Conclusions 144 Literature Cited 147 Appendix A: Lactose Content of Milk and Other Dairy Products 165 Appendix B: Recruitment Posters and Advertisements 167 Appendix C: Ethical Review Acceptance Letter 169 Appendix D: Questionnaire 171 Appendix E: Original Attitude Statements and their References 180 Appendix F: Pre-Testing Questionnaire 182 Appendix G: Validity Test 184 Appendix H: Reliability Test 188 Appendix I: Cover letter 204 Appendix J: "Other" Ethnicities Listed Verbatim 206 vi Appendix K : Foods Avoided by Vegetarian Participants 208 Appendix L: List of Non-Associated Symptoms 210 Appendix M : Other Tests Used in Diagnosis 213 Appendix N : Information Sources Listed Verbatim by Participants for Finding Information on Lactose Intolerance 216 vii List of Tables Chapter II: Literature Review Table 2.1: Suggested levels of lactose tolerance 21 Table 2.2: Calcium intake (mg/day) by age-sex as reported in the National Health and Nutrition Examination Survey (NHANES) III, 1989-1990 29 Table 2.3 Calcium intake (mg/day) by age-sex as reported in Food Habits of Canadians study, 1997-1998 31 Chapter III: Methodology Table 3.1: Scoring of statements included in attitudes to dairy products scale 56 Table 3.2: Questionnaire items for which frequency statistics were generated 58 Table 3.3: Questionnaire items for which descriptive statistics were generated 59 Table 3.4: Comparisons for which t-tests were used to compare two means 59 Table 3.5: Comparisons for which analysis of variance was used to compare three means 60 Table 3.6: Comparisons for which X 2 were calculated 61 Table 3.7: Comparisons for which Fisher's exact tests were calculated 61 Table 3.8: Associations for which Pearson correlations were calculated 62 Chapter IV: Results Table 4.1: Sources of participant recruitment 63 Table 4.2: Frequency and percent of subjects in different age categories by gender 64 Table 4.3: Ethnicity of study participants 65 viii Table 4.4: Distribution of self-described ethnicity 66 Table 4.5: Educational background of participants 67 Table 4.6: Mean calcium intake and proportion meeting calcium Adequate Intake (AI) using estimate calcium intake from food sources only and calcium fortified beverages 69 Table 4.7: Percentiles of calcium intake from food sources 70 Table 4.8: Daily calcium intake from supplements by gender and age group 72 Table 4.9: Percentiles of calcium intake from supplementary sources 73 Table 4.10: Participants meeting calcium AI using calcium intake from food and supplementary calcium sources 74 Table 4.11: Percentiles of total calcium intake from food and supplementary sources combined, by gender 75 Table 4.12: Calcium intake and ability to meet Adequate Intake by participants' inclusion or exclusion of milk products and dairy products from their diet 76 Table 4.13: Mean calcium intake from food sources and ability to meet Adequate Intake by participants' inclusion or exclusion of cheese and yogurt from their diet 77 Table 4.14: Mean calcium intake from food sources for current, past and never vegetarians 78 Table 4.15: Mean calcium intake from supplementary sources for current, past and never vegetarians 79 Table 4.16: Mean calcium intake from food and calcium supplements combined for current, past and never vegetarians 80 Table 4.17: Frequency and percent of perceived symptoms of lactose intolerance reported by study participants 81 Table 4.18: Symptoms reported by those who did or did not experience non-associated symptoms (NAS) 82 i x Table 4.19: Severity of symptoms experienced following the consumption of one cup of milk (any fat content) with a meal 83 Table 4.20: Self-diagnosis or the involvement of a health care practitioner in the diagnosis of lactose intolerance 84 Table 4.21: Diagnostic tools used by all health care practitioners in the diagnosis of lactose intolerance 85 Table 4.22: Tests used by diagnosing health care practitioners 86 Table 4.23: Other tests used in physician diagnosed lactose intolerance 87 Table 4.24: Food, supplemental and total calcium intake among self-diagnosed and physician-diagnosed participants 87 Table 4.25: Participant responses to knowledge statements 89 Table 4.26: Attitude statements regarding milk and dairy products: frequency of participant responses on a Likert agreement scale 91 Table 4.27: Correlations for calcium intake from food sources and attitude statements 92 Table 4.28: Attitude scale scores by age group 94 Table 4.29: Mean scores for attitude statements by gender 95 Table 4.30: Mean scores for attitude statements by vegetarian status 97 Table 4.31: Attitude scale scores by level of formal education 98 Table 4.32: Tendency of food items to cause or not cause discomfort (percent) 100 Table 4.33: Frequency and percent of participants reporting information sources used to gather information on lactose intolerance.. 101 Table 4.34: Most useful information sources listed by participants 102 Table 4.35: Information sources participants would use for more information on lactose intolerance 104 Table 4.36: Percent of participants wanting further information on lactose intolerance 105 Appendices: Table A. 1: Lactose content of milk and other dairy products* 166 Table E . 1: Original Attitude Statements and their References 181 Table H. 1: Test-retest correlations for response options to "how did you first hear about lactose intolerance? 191 Table H.2: Test-retest correlations for a person's decision that they were lactose intolerant.... 191 Table H.3: Test-retest correlations for symptoms of lactose intolerance 192 Table H.4: Test-retest correlations for symptom severity with one cup of milk, and involvement of a health care practitioner in diagnosis of lactose intolerance 193 Table H.5: Test-retest correlations for use of diagnostic procedures 193 Table H.6: Test-retest correlations for items in the lactose intolerance knowledge scale 194 Table H.7: Test-retest correlations of the attitude and opinion scale 195 Table H.8 Test-retest correlations for milk, dairy products and discomfort scale items 196 Table H.9: Test-retest correlations of items used in the food frequency questionnaire for calcium intake estimation 197 Table H. 10: Test-retest correlations for calcium supplement use 198 Table H. 11 Test-retest correlations for vegetarianism among study participants 198 Table H. 12: Test-retest correlations for reported information sources 199 Table H . 13: Test-retest correlations for most used sources 200 Table H. 14: Test-retest correlation for future information sources 200 Table H. 15: Test-retest correlations for information needs statements 201 Table H. 16: Test-retest demographic correlations 201 Table H.17: Scale internal consistency and reliability 202 x i List of Figures Chapter V : Discussion Figure 5.1: Details of potential modifications to Calcium Calculator ™ tool 133 xii Acknowledgements This work is dedicated to my mentors, and to my family and friends who have supported me throughout the twists and turns of recent years. Special thanks to my committee members, Susan Barr and Ryna Levy-Milne, and also to Charles Fontaine, Tracey Kerr and Heather Kovacs for their unending support and editing efforts! Chapter I: Introduction/Rationale Introduction/Rationale Since the 1970s, an abundant amount of research has been performed regarding lactose intolerance, lactose maldigestion, and the quantity of lactose that can be consumed before symptoms of lactose intolerance are induced. Research has also been performed to characterize abdominal complaints associated with lactose intolerance, and the severity of such complaints. The physiology of lactose maldigestion and intolerance has been described (McBean & Miller, 1998). Similarly, research has been performed to characterize the induction of the lactase enzyme, microfloral B-galactosidase, and colonic adaptation to lactose by increased milk consumption (Herzler & Savaiano, 1996; Briet et al., 1997). Research into the relationships between dietary habits and symptoms of lactose intolerance has tried to address whether the consumption of a meal (Martini & Savaiano, 1988), the fat content of fluid milk being consumed (Solomons, Garcia-Ibanez & Viteri, 1979; Cavalli-Sforza & Strata, 1987; Vesa, Lember & Korpela, 1997), or the timing of milk consumption are implicated in the appearance or minimization of intolerance symptoms (Martini & Savaiano, 1988). The development of lactose digestive aids (lactase preparations) and lactose reduced products stimulated research into the efficacy of lactase preparations in reducing symptoms of lactose intolerance (McBean & Miller, 1998). It appears that there are widespread misperceptions in the population about lactose intolerance (McBean & Miller, 1998). Studies have repeatedly identified that more people claim to be lactose intolerant than truly are (Suarez, Savaiano, & Levitt, 1995; Vesa, Korpela, & Sahi, 1996; Suarez, Savaiano, Arbisi, & Levitt, 1997). However, there has been little research to study the basis by which people determine or perceive that they are lactose intolerant, and the 1 Chapter I: Introduction/Rationale implications of this determination for their diet. Similarly, the role of psychological factors in the perception of lactose intolerance has received little attention. A review of popular media sources suggests that media advertisements and promotions provide information that individuals may use to self-diagnose various conditions. Misinterpretation is a problem with self-testing devices (Lowell, 1995), and this may extend to self-diagnosis procedures. Self-diagnosis that is based on a generalized list of symptoms for lactose intolerance may be subject to misinterpretation and may defer the diagnosis of other, more serious gastrointestinal conditions (McBean & Miller, 1998). With consumers assuming more responsibility for their own disease prevention practices, they accept self-testing devices or procedures and interpret promotional materials of pharmaceutical companies in light of their own situations (Lowell, 1995). This phenomenon may extend to media coverage of health conditions such as lactose intolerance and relate to the increased prevalence of people who self-report lactose intolerance. People with lactose intolerance can often consume some dairy products without experiencing discomfort (Gudmand-Hoyer & Simony, 1977; Cavalli-Sforza & Strata, 1987). Testing dairy products in different amounts, or in combination with other foods or digestive aids (on an individual basis), may identify certain dairy products, and quantities of individual products, that can be tolerated (Rosado, Allen & Solomons, 1987; McBean & Miller, 1998). However, the extent to which this self-testing occurs in individuals with lactose intolerance is unknown. Furthermore, there is little quantitative information identifying dietary characteristics of individuals with lactose intolerance. It has been reported, however, that some individuals with lactose intolerance may completely avoid dairy products to the potential detriment of their overall nutritional status (McBean & Miller, 1998). In British Columbia, individuals who have 2 Chapter I: Introduction/Rationale medical barriers to milk consumption (lactose intolerance or milk allergy) tend to hold more negative opinions of milk than those without medical barriers (Commins & Wingrove, 2000). Individuals in British Columbia with medical barriers were more likely to limit milk consumption when compared to the national average of those with medical barriers (Commins & Wingrove, 2000). Accordingly, this study is oriented to determining patterns of dairy product consumption, and assessing attitude towards milk and dairy products. A literature search of Medline (1966-January 2002) and its associated databases did not reveal published studies regarding the practices and thoughts of individuals with lactose intolerance. However, studies performed during the past three decades provided some information about milk-drinking habits among individuals with lactose intolerance. The current research project should help elucidate the current thoughts and practices of individuals with self-reported (perceived) lactose intolerance, with regard to their consumption of dairy products and calcium. It will also help expose the amount of knowledge currently held by people with self-reported lactose intolerance, and the type of misconceptions (if any) that fall within that knowledge. The information provided by this research may identify knowledge gaps in the population of individuals with self-reported lactose intolerance. Similarly, the research should identify the types of information, and methods of information dissemination that would be most likely to reach the people who would be consumers of the information. The research aims to identify appropriate and trusted information sources, for incorporation into communication and education planning in order to increase education effectiveness and efficiency in reaching the target population. 3 Chapter I: Introduction/Rationale The findings will provide information for developing materials to address misinformation that people with lactose intolerance may hold, and to communicate the current state of scientific information on lactose intolerance. The research results will be provided to the B.C. Dairy Foundation so that they can address any identified knowledge gaps, and develop well-situated educational materials based on these gaps. The findings will also have implications for physicians or dietetic clinicians whose.practice involves clients with lactose intolerance, and may suggest new information on lactose intolerance for distribution, and new methods of presenting clients with information about lactose intolerance. 4 Chapter II: Literature Review Literature Review Relevant literature that was reviewed includes literature regarding lactose maldigestion and lactose intolerance, diagnostic methods for lactose maldigestion and lactose intolerance, consumption and importance of dairy products, prevalence of lactose intolerance, sensitivity to lactose ingestion, and the lactose content of various food items. Additionally, attitudes/perceptions were reviewed given their potential influence on dairy product consumption and self-diagnosis of lactose intolerance. The role of information sources, and the knowledge of regulations surrounding the production of dairy products was reviewed. Lactose Maldigestion and Lactose Intolerance Lactose, a disaccharide formed by beta-glycosidic linkage of glucose and galactose, is the sugar found in dairy products and is commonly known as "milk sugar" (McBean & Miller, 1998; Inman-Felton, 1999). It is digested by lactase, an enzyme embedded on the surface of cells in the small intestine that functions to cleave lactose into its component parts of glucose and galactose. (Galactose is later converted to glucose in the liver). When lactase is absent from the small intestine, or is present only in small quantities, lactose may pass through the small intestine into the large intestine where it will undergo bacterial fermentation. Acid and gaseous breakdown products of lactose in the small intestine may result in gastrointestinal symptoms. The resulting symptoms of such lactose maldigestion are termed lactose intolerance. Some previous studies have used the terms "lactose intolerance" and "lactose maldigestion" interchangeably. Inaccuracy in terminology calls into question the validity of research results, because lactose intolerance and lactose maldigestion are not one and the same. Lactose maldigestion is the inability to digest the milk sugar lactose due to a deficiency of the 5 Chapter II: Literature Review digestive enzyme lactase (Inman-Felton, 1999). This may or may not result in the gastrointestinal symptoms of stomach bloating, cramps, gas and/or diarrhoea. These resultant gastrointestinal symptoms are indicative of lactose intolerance (Bayless et al., 1975). Lactose maldigestion is a normal physiologic pattern, commonly occurring between the ages of two and twenty, as a physiological process whereby the production and function of lactase enzyme is reduced (Inman-Felton, 1999). An underlying disease, condition or medication that affects the gastrointestinal tract (such as celiac disease) may also cause lactose maldigestion - but in this case, the lactose maldigestion is termed secondary maldigestion (Inman-Felton, 1999). Another cause of lactose maldigestion occurs at birth as a result of a relatively rare genetic abnormality where the lactase enzyme is low or non-existent (Inman-Felton, 1999). To differentiate between lactose maldigestion and lactose intolerance, it is important to understand that lactose intolerance is the experience of gastrointestinal intolerance symptoms resulting from the excessive undigested lactose that moves into the large intestine, and its fermentation in the large intestine (Bayless et al., 1975). Any combination of lactose maldigestion or digestion and lactose tolerance or intolerance may occur. This study focussed on perceived lactose intolerance, which potentially included individuals falling into one of two categories: symptomatic lactose maldigestors (true lactose intolerance, with symptoms such as cramps and diarrhea after ingestion of large amounts of lactose); symptomatic lactose digestors (experience symptoms of intolerance (e.g., cramps, diarrhea) or other physical complaints (headache, insomnia) not due to maldigestion). 6 Chapter II: Literature Review Prevalence of Lactose Maldigestion Lactose maldigestion is a genetically determined trait (Bayless et al., 1975; Johnson, Semenya, Buchowski, Enwonwu, & Scrimshaw, 1993). The prevalence of lactose maldigestion and the associated symptoms of lactose intolerance may be increasing in Canada because of increasing ethnic diversification of the population. Research has suggested that greater than two-thirds of randomly selected individuals of African, Asian, First Nations, Jewish and Mexican heritage are lactose maldigesters (Bayless et al., 1975; Johnson et al., 1993). As the background of Canadian people diversifies, the proportion with lactose maldigestion and potentially with lactose intolerance, may increase substantially. Increased media attention to lactose intolerance and increased availability of lactose-reduced products may also lead more people to perceive that they are maldigesters/intolerant. Methods of Diagnosis Lactose maldigestion can be diagnosed using one of several different testing methodologies. However, lactose intolerance cannot be predicted from a diagnosis of lactose maldigestion (McBean & Miller, 1998). Lactose intolerance can only be diagnosed by combining clinical symptoms following the ingestion of a lactose load with the results of an accepted test for lactose maldigestion, preferably under blinded conditions. Jejunal Biopsy The jejunal biopsy is a procedure in which a small portion of the jejunum is removed from the patient for examination of the mucosa, enterocyte ultrastructure and to assay enzyme activity (Villako & Maroos, 1994). This is the most accurate method for determining lactase activity, and therefore maldigestion (Sahi, 1994). For patients with suspected lactose 7 Chapter II: Literature Review maldigestion and subsequent lactose intolerance, the jejunal biopsy can be performed to determine the ratio of lactase to sucrase. The lactase activity, while decreased compared to what would be considered a normal activity, may vary from low to high, indicating either a low or high ability to digest lactase. In some cases, biopsy samples from different parts of the jejunum may have different enzyme levels, as some conditions may cause changes that occur in portions, or patches, of the jejunum (Villako & Maroos, 1994). In secondary lactose maldigestion, or maldigestion that occurs as a result of another condition, features of the jejunal mucosa are important in the diagnosis of the condition causing the secondary lactose maldigestion. The jejunal biopsy is more frequently utilized in the diagnosis of secondary than primary maldigestion, because the procedure is invasive and other available diagnostic procedures are adequate for primary maldigestion. Lactose Tolerance Test The lactose tolerance test refers to a blood test that reflects lactase deficiency of enterocytes (Jacobs, Grady, Horvat, Huestis & Kasten, 1996). Digestion of lactose involves the release of glucose and galactose molecules and subsequent uptake into the bloodstream. If lactose is digested, a rise in the blood glucose level should be observed following ingestion of an oral lactose load. Blood glucose is therefore analyzed after the ingestion of an oral lactose load, and the increase or lack of increase in blood glucose compared to the fasting level is interpreted for the diagnosis of lactose maldigestion (Jacobs et al., 1996). To determine changes in blood glucose, blood samples should be drawn while fasting, and subsequent samples drawn 30 minutes, 1, 2, 3, and 4 hours after the ingestion of the lactose load (Jacobs et al., 1996). Symptoms should be recorded for the duration of the test and the individual should be examined for clinical signs of distension. A rise in blood glucose of 30 8 Chapter II: Literature Review mg/dL is considered normal, following a lactose load of 50 g (Jacobs et al., 1996). An increase of <20 mg/dL is considered abnormal, and when accompanied by symptoms of intolerance (gas, abdominal pain), it is considered evidence of lactase deficiency and a diagnosis of lactose intolerance due to symptoms is indicated. Lactose loads of 50 g or 1 g/m body surface are recommended for the lactose tolerance test (Jacobs et al., 1996; Tierney, McPhee & Papadakis, 2000) despite research indicating that lower doses (15 g) are acceptable (Solomons, Garcia-Ibanez & Viteri, 1980). While some textbooks that outline testing procedures mention that a 15 g lactose load has been suggested for use, it is only advised for use in children or individuals suspected of having severe intolerance (Jacobs et al., 1996). Breath Hydrogen Test The breath hydrogen test, sometimes known as the lactose breath hydrogen test (LBHT), is currently the gold standard for the determination of lactose maldigestion (McBean & Miller, 1998). The test requires only the determination of hydrogen in expired air following an oral lactose load, and is therefore a simple, well-tolerated, non-invasive procedure by which low intestinal lactase activity can be diagnosed (Solomons et al., 1980; Welsh & Griffiths, 1980). The breath hydrogen test for lactose tolerance is based on the production of hydrogen by bacterial fermentation of carbohydrate that has entered the large intestine (Welsh & Griffiths, 1980). Lactose that is not digested by lactase in the small intestine passes through the gastrointestinal system until the bacterial microflora of the large intestine metabolize the lactose. During the degradation, hydrogen gas is produced (Jacobs et al., 1996). Hydrogen is present in expired air, after being absorbed through the intestinal mucosa into the blood stream, where it is 9 Chapter II: Literature Review carried to the lungs (Welsh & Griffiths, 1980). Therefore, expired breath hydrogen provides an index of hydrogen production in the intestine and the amount of malabsorbed lactose. To detect changes in breath hydrogen, an aqueous lactose load is administered to the individual being tested after an overnight fast. Mid or end expired breath samples are taken at baseline (before ingestion of the lactose load) and then every 10 minutes thereafter for two to six hours (Solomons et al., 1980; Welsh & Griffiths, 1980). Hydrogen concentration in expired air is determined by gas chromatography. The increase in breath hydrogen level selected to establish maldigestion ranges from >10 ppm to >20 ppm, although medical texts note that subjects with lactase deficiency generally have breath hydrogen increases >50 ppm (Jacobs et al., 1996). A rise of >20 ppm is the standard rise accepted to indicate lactase deficiency because researchers have established that a rise >20 ppm corresponds to a blood glucose rise < 20 mg/dL in the blood glucose test (Jacobs et al., 1996). The standard dose for the breath hydrogen test ranges from 12.5 g to 50 g (McBean & Miller, 1998). The 50 g lactose load has been criticized because it compares to having an individual consume approximately 1 L of milk in one sitting (Solomons et al., 1980). This constitutes a non-physiological dose, and does not provide information on maldigestion of smaller, more physiologic doses. Additionally, because of rapid gastric emptying of liquids, the dose itself contributes to the onset of intolerance symptoms. This may contribute to the incorrect belief that lactose causes symptomatic response regardless of dose consumed (McBean & Miller, 1998). The 12.5 g lactose load is considered more appropriate, because it is a physiologic dose corresponding to the ingestion of one cup (250 mL) of milk. Maldigestion established from the consumption of this smaller dose could allow practitioners to distinguish between individuals who could consume some lactose in the diet and those who may require a very low lactose, or 10 Chapter II: Literature Review lactose-free diet (Zuccato et al., 1983). Despite the arguments for using 12.5 g lactose loads, and the shift towards using this load in research studies, a 50 g load is most commonly recommended by medical textbooks (Jacobs et al., 1996; Tierney et al., 2000). Clinical Symptom Evaluation Current diagnostic and laboratory medicine textbooks may directly advise doctors to have patients withdraw lactose-containing foods from the diet before recommending a lactose tolerance test (Jacobs et al., 1996; Tierney et al., 2000). This procedure is advocated because the individual may experience relief from symptoms, in which case practitioners are advised not to perform the test (Jacobs et al., 1996). Doctors are then advised to make the diagnosis of lactose intolerance based on symptoms and relief of symptoms following to lactose removal from the diet. A recent position statement regarding evaluation of chronic diarrhea supports this practice for evaluating lactose intolerance, and advocates the careful use of diet history combined with very judicious use of further testing methodology (American Gastroenterological Association, 1999). Furthermore, medical reference texts suggest that lactase deficiency can be inferred from the effects of ingestion of milk (Jacobs et al., 1996), despite research literature that does not support this claim. Villako and Maroos (1994) stated that symptomatic responses following ingestion of milk or dairy products cannot be used to diagnose lactose maldigestion. Their review indicated that it was impossible to differentiate between patients with low and high lactase levels on the basis of symptoms alone: of 220 individuals with unspecific abdominal complaints thought to be associated with milk consumption, only 69% were found to have low lactase levels. The evaluation of clinical symptoms rather than diagnosis using clinically 11 Chapter II: Literature Review relevant acceptable tests for lactose maldigestion may therefore be implicated in the finding that many people who think they are lactose intolerant, are not. Fecal pH Analysis Fecal pH analysis is another method that can be used to diagnose lactose maldigestion. As previously noted, hydrogen gas is produced when undigested lactose passes into the large intestine. The production of hydrogen gas decreases the pH of concomitant fecal material. Fecal pH analysis therefore provides a measure of lactose maldigestion. Laboratory analysis indicating values of fecal pH greater than 6.0 are reflective of carbohydrate absorption, while pH values less than 6.0 reflect malabsorption (Maffei, Daher & Moreira, 1984). The fecal pH analysis is less commonly used than the breath hydrogen test, or the lactose tolerance test. In diagnostic and laboratory medicine textbooks, the test is not mentioned as a diagnostic procedure for the evaluation of lactose maldigestion, despite the use of the method in research publications. However, it is more commonly used than other methods to diagnose lactose intolerance in children (Fagundes-Neto, Viaro & Lifshitz, 1985; Wallach, 1998), who are more prone to severe and potentially life-threatening dehydration from diarrhea than adults (Gracey & Burke, 1973; Walker & Harry, 1973). The values for fecal pH, while indicating carbohydrate malabsorption, are not predictive of intolerance symptoms (Maffei et al., 1984). The clinical findings of fecal pH are less useful than other tests for lactose maldigestion and may be used to confirm other findings. Current textbooks mention fecal pH <6.0 as a clinical finding in lactose maldigestion with no mention as to the use of the fecal pH test as a diagnostic procedure (Tierney et al., 2000). 12 Chapter II: Literature Review Diagnosis by Complementary and Alternative Medicine Practitioners Complementary and alternative medicine practitioners may also diagnose lactose intolerance, and perhaps even lactose maldigestion, but little is known about the procedures by which either are determined in a complementary or an alternative health setting. Anecdotal reports of lactose intolerance diagnosed by these practitioners have not included any diagnostic procedure other than discussion of abdominal complaints. Some reports have mentioned diagnosis on the basis of skin conditions such as eczema. Traditional Chinese Medicine Traditional Chinese Medicine is often seen as an alternative to Western medicine, due to the divergent perspectives and approaches to physiology and healing that underlie the two forms of health care. Western medicine is a system of organs, hormones and cellular activity. Traditional Chinese Medicine focuses on meridian pathways and their acupuncture points, qi, Chinese blood, essence and spirit (Personal communication, Dr. Lome Brown, Doctor of Traditional Chinese Medicine, 2000). Chinese medicine views medicine from the perspective that the person is a unified organic whole; not just a body but a whole person. Spiritual, mental, emotional and physical aspects of the person are seen as interrelated and interdependent. While Western medicine's diagnosis treats illness by isolating the affected area and using medications to reverse the problem, the diagnostic procedures of Chinese medicine identify which parts of the whole are out of balance, and how energy patterns are altered. Energetic and herbal therapies are given to correct any imbalance, and bring the whole back to stasis. In some cases, Chinese medicine can treat diseases that are considered "incurable" by Western medicine, and energy imbalances that respond poorly to Western medicine. 13 Chapter II: Literature Review In Traditional Chinese Medicine, the diagnostic process uses five areas of examination: looking, hearing, smelling, questioning and touching (Personal communication, Dr. Lome Brown, Doctor of Traditional Chinese Medicine, 2000). Questioning often uses a self-assessment tool, where a patient checks off (from a list) symptoms experienced. This is used as both a diagnostic aid and an educational device. Symptoms fall within categories, and these categories form the background for the diagnosis. Lactose intolerance, seen as a food intolerance, may fall under the category of conflicts between organ networks - the symptoms indicate liver-spleen disharmony (Personal communication, Dr. Lome Brown, Doctor of Traditional Chinese Medicine, 2000). Liver-spleen disharmony does not refer to problems of anatomical liver and spleen, but the Chinese concept of the liver and spleen. (The Chinese spleen is where the energy of food and fluid is transformed). Alternatively, lactose intolerance may result from spleen deficiency (Chinese spleen) or dampness in the middle burner. Theoretical treatments for lactose intolerance include acupuncture and herbal remedies designed to increase energy of the kidney and spleen (Chinese concepts), and remedies to eliminate dampness. Part of Traditional Chinese Medicine is the idea that all individuals are unique and that uniqueness should be respected. As a result, a practitioner may request that a person not consume milk or products containing milk rather than making a treatment recommendation (Personal communication, Dr. Lome Brown, Doctor of Traditional Chinese Medicine, 2000). Due to the different perspective of health and healing in Traditional Chinese Medicine, "lactose intolerance" is not a diagnosis that would be made by a Traditional Chinese Medicine practitioner (Personal communication, Dr. Lome Brown, Doctor of Traditional Chinese Medicine, 2000). An individual with symptoms of lactose intolerance would be diagnosed as 14 Chapter II: Literature Review having liver-spleen disharmony. Therefore, further research into the diagnosis of lactose intolerance by Traditional Chinese Medicine practitioners would not be fruitful. Naturopathic and Homeopathic Medicine Naturopathy and homeopathy are alternative and complementary medical fields in which diagnosis and treatment are heavily dependent on observation and experience (Bayley, 1993). There is scepticism over the diagnosing and curative abilities of these alternative health care practices and the theoretical basis on which recommendations are made (Linde et al., 1997; Bayley, 1993). Personal accounts have indicated that both naturopathic and homeopathic physicians are involved in the diagnosis of food allergies and intolerances. A literature review of naturopathic and homeopathic diagnosis revealed studies that detailed diagnostic methods for food allergies and intolerances. While little information is available, a study is currently being performed at the University of Calgary regarding the general problems seen in practice, methods of diagnosis and therapeutic regimens (Personal communication, Dr. Marja Verhoef, Community Medicine, 2001). Several tests are recognized as useful and valid in the testing of patients for potential allergies. While naturopathic and homeopathic physicians are unable to order or administer these tests, they are able to suggest them to patients through their family physician. The standard tests include the scratch test, serial dilution intradermal test, sublingual challenge test, deliberate feeding (provocation and challenge) test and the RAST test (radioallergosorbent test). These methods are categorized as ecological testing methods. Provocation testing is accepted as the most valid, however, RAST testing, while most expensive and not optimally correlated to the provocation test (Bahna, 1991), is specific and advantageous. Blood can be drawn from the 15 Chapter II: Literature Review patient, and then tested against allergens for immune (IgE) response without exposing the patient to allergens or to potentially uncontrolled reactions seen in the provocation test (Krop, Swierczek & Wood, 1985). Unlike allergies, few tests have proven useful to determine intolerances. Lactose intolerance can only be determined by a diagnosis of lactose maldigestion based on test results accompanied by clinical symptoms of intolerance. Again, naturopathic and homeopathic physicians do not have access to ordering or administering tests to diagnose lactose maldigestion. One naturopathic physician reports his diagnostic criterion for lactose intolerance as being the description of symptoms (Personal communication, Dr. Ronald Reichert, Doctor of Naturopathic Medicine, 2001). This practice, as previously mentioned, is potentially detrimental to the patient and is not recommended. However, diagnosis of intolerance may include the use of tests developed outside of the medical model. The Vega Test method is a bioenergetic regulatory technique (Krop et al., 1985). It uses differences in measured bioelectrical potential in an attempt to determine allergies. Vega Testing is proposed by some alternative health care practitioners as a method of determining patients' sensitivity to particular antigens, and has been extended in its use for the determination of food intolerances. The extent to which the test is used is thought to vary widely among naturopathic and homeopathic physicians. The Vega Testing procedure uses a battery to provide a current. Electrodes are then attached to the patient at two places - one hand, and the opposite foot. Electrical potential is then measured to obtain a baseline reading. Next, a food substance (thought to generate and transmit) is added into the circuit and the electrical potential is measured again. A drop in the electrical potential is understood to indicate a sensitivity or allergy to the item being tested (Krop etal., 1985). 16 Chapter II: Literature Review In 1985, Krop and colleagues compared the Vega Test to standard ecological tests used to diagnose food allergies. Forty-three participants, known to suffer from environmentally induced illnesses were tested for food, chemical and inhalant allergies using both the Vega Test and ecological tests. Tests were performed independently on the same day by different technicians. Limited results of the Vega test in comparison to the ecological tests were presented. In fact, no raw data or statistical analysis were presented. However, a table presented figures that suggest Vega testing indicated an allergic reaction to food antigens in six cases where ecological testing found no reaction. For both inhalant and chemical sensitivities, the Vega testing indicated an allergic reaction in 18 cases where the ecological tests found none. The possibility of false positive results was not discussed. The conclusions drawn by this study are not strong conclusions due to limitations in study design. While different technicians were used to perform the different tests, the potential allergens were not blinded from the technicians; nor was a placebo substance used. Additionally, only two ecological tests were used in comparison to the Vega test. Sublingual and intradermal methods were used but not the provocation or RAST tests, which are considered the gold standards. The intradermal method is not always considered reliable as certain skin conditions may alter test specificity and/or sensitivity (no mention was made of participant inclusion criteria for this study) suggesting that further studies comparing Vega testing to more reliable methods are necessary. Until then, the use of Vega testing and its basis in putative energy-generation remains questionable. Even the need for further study is questionable. Vega testing has been refuted by the Australian College of Allergy as unorthodox and inappropriate (Katelaris, Weiner, Heddle, Stuckey, & Yan, 1991). Furthermore, the study of the Vega test's theoretical base has indicated the false representation of ideas with no basis in science (Cole & St. George, 1993). 17 Chapter II: Literature Review Another test used anecdotally for the diagnosis of food allergy and intolerance is the "bi-digital o-ring test". The bi-digital o-ring test was developed as an imaging technique to replace imaging techniques that expose patients to undesirable radiation (Omura, 1985). The technique is designed on the theory that problems occurring within individual's internal organs may be tested by simply holding a sample of the same tissue (desiccated or in slide form). A sample of a tissue would be held in one hand, and a bi-digital o-ring (formed with the thumb and index finger) is formed with the other hand. If the bi-digital o-ring formed by the opposite hand is broken (if fingers are pulled apart) more easily when holding the tissue sample compared to when not holding the sample, the same tissue within the individual is problematic. The bi-digital o-ring test has been applied to test food and drug compatibility (Omura, 1981), where a food sample is to be held, and the breaking of the bi-digital o-ring represents sensitivity. A literature search did not reveal any randomized, controlled trials to test the validity or reliability of the bi-digital o-ring test in comparison to commonly accepted methods for allergy and intolerance testing. However, some practitioners of naturopathic and homeopathic medicine are thought to still practice the technique despite the lack of diagnostic evidence. This necessitates research into the diagnostic practices used by practitioners of alternative and complementary medicine to determine their potential for diagnosis or misdiagnosis of lactose intolerance. Association Between Lactose Maldigestion and the Experience of Symptoms Studies have suggested that more individuals claim to be lactose intolerant than truly are. Research has identified an imperfect correspondence between lactose maldigestion and lactose intolerance. In 1975, Bayless and colleagues found that 54% of 166 male subjects were 18 Chapter II: Literature Review classified as lactose maldigesters and lactose intolerant on the basis of a blood test for lactose maldigestion. Only 64% of these subjects indicated prior knowledge of intolerance to milk consumption. Results of a questionnaire administered in the same study showed that 35% of patients who tolerated lactose (lactose digesters) indicated that they experienced milk-induced symptoms (Bayless et al., 1975). Lactose load testing of this tolerant group found that only 3% exhibited symptoms. Interpretation of this study's results is limited since no indication was provided of the order in which the lactose tolerance test and questionnaire were administered. If lactose tolerance testing occurred before the questionnaire and heavy load testing, subjects may have been biased to react to the milk or identify the reaction in the questionnaire. However, the evidence presented suggests the subjects' tendency to indicate a reaction to milk or lactose where a true reaction was not found. This tendency for people to incorrectly self-diagnose lactose intolerance when lactose maldigestion does not exist has been substantiated in more recent studies (Suarez et al., 1995; Suarez et al., 1997; Vesa et a l , 1996). Nine of 30 participants (-30%) self-reporting severe lactose intolerance were found to be lactose digesters when tested using a breath hydrogen test (Suarez et al., 1995). Furthermore, even among lactose maldigesters, participant scores of symptom severity were not significantly different between lactose-hydrolyzed milk (2%) and regular milk (2%) sweetened with aspartame to minimize taste recognition between the two milk drinks, suggesting that abdominal symptoms are misattributed to lactose intolerance. Similar findings by Vesa, Korpela & Sahi (1996) lend credibility to this idea, although the study tested small lactose doses in comparison to the doses used by Suarez, Savaiano and Levitt. Vesa and colleagues tested 39 lactose maldigesters and 15 lactose digesters in a randomized, crossover, double-blind trial. No significant differences were found in severity of symptoms, and symptoms occurred 19 Chapter II: Literature Review inconsistently in ~60% of maldigesters during random consumption of the 200 mL test milks, containing 0, 0.5, 1.5 and 7 g lactose. Significantly more bloating was reported by lactose maldigesters (Vesa et al., 1996). In later studies, Suarez and colleagues (1997) indicated that individuals with self-reported severe lactose intolerance and non-lactose intolerant individuals reported similar symptoms after consuming lactose-hydrolyzed and regular milk (Suarez et al., 1997). Those with self-reported severe intolerance did however report more underlying flatulence than non-intolerant participants, suggesting that flatulence may relate to incorrect self-reporting of lactose intolerance. Sensitivity to lactose ingestion among individuals with lactose intolerance varies considerably (Gudmand-Hoyer & Simony, 1977; Cavalli-Sforza & Strata, 1987; McBean & Miller, 1998). Interventions that have used increasing lactose loads, have indicated that the proportion of subjects with symptom response to the lactose load increases as lactose load increases (Gudmand-Hoyer Simony, 1977). See Table 2.1. Similarly, severity of response increases with increasing lactose loads; in a randomized, cross-over, double blind trial, research participants reported increased abdominal pain intensity when lactose loads were 12 g compared to 3 g or 6 g doses (Hertzler, Huynh & Savaiano, 1996). However, lactose accounted for only 6.9% of symptom variability, in combination with other factors such as dose (quantity of milk ingested) and fat content (Cavalli-Sforza & Strata, 1987). Researchers have concluded that the severity of lactose intolerance symptoms depends on the amount of lactose consumed (Hertzler et al., 1996). While it is commonly accepted that symptoms and severity of lactose intolerance vary according to the dose of lactose ingested, some research suggests that a threshold may exist below which symptoms are not observed. A study on tolerance to small amounts of lactose suggested that no dose-response 20 Chapter II: Literature Review Table 2.1: Relationship of lactose load to symptoms experienced among individuals with lactose intolerance. Article Study Design n Lactose load Percent of participants (g) with symptoms Gudmand-Hoyer & Simony, Non-cross 20 3 10 1977 over, non- 6 25 random, non- 12 75 blinded 24 85 48 95 96 100 relationship exists for low levels of lactose <7 g (Vesa et al., 1996). In this double-blind control trial, participants consumed lactose-free milk, and milk containing 0.5, 1.5 and 7 g of lactose per 200 mL drink. A l l milks were chromatographically treated to remove lactose, and subsequently subjected to treatment with beta-galactosidase to remove any trace amounts of lactose remaining. Lemon-flavouring and sugar were used to equalize taste, sweetness and osmolality of the drinks to ensure that participants did not know which drink they were consuming. Data analysis indicated that participants experienced more symptoms when consuming the lactose-free milk than the 0.5 g lactose-containing milk. While these data suggest a lack of dose-response, the authors identified that it may also suggest a study design flaw. The study design was intended to exclude confounding factors but this finding indicates the possibility that symptoms were due to factors other than lactose intolerance (Vesa et al., 1996). Alternately, this potential flaw supports the theory that lactose intolerance, particularly when self-diagnosed, may be attributed to a variety of symptoms. Other studies on lactose ingestion and symptomatic response are contradictory. In a study where individuals with lactose intolerance consumed 240 mL milk each day over a one-week period, symptoms experienced were minimal (Suarez et al., 1995). This suggested that the 21 Chapter II: Literature Review consumption of approximately one cup (250 mL) of milk among individuals with lactose intolerance is well tolerated, contradicting earlier research by Bayless et al., (1975) whose study indicated the opposite. Bayless and colleagues found that most people with lactose intolerance experienced symptoms after consuming one cup (250 mL) of milk. However, this was an uncontrolled study, which did not account for symptom intensity. Furthermore, study participants were recruited from a hospital setting with no mention of the underlying reason for hospitalization. It is plausible that the reason for hospitalization could have influenced symptomatic response. It has been reported that many individuals with lactose intolerance discontinue their intake of milk and other dairy products due to their symptomatic experiences. While individuals may be counselled to do so, this discontinuation is not always necessary. As mentioned previously, lactose maldigesters can determine their own threshold intakes and adjust their intake to a comfortable level of consumption (McBean & Miller, 1998). Tolerance may vary between dairy foods due to different levels of lactose present. Low lactose dairy products may therefore be better tolerated (McBean & Miller, 1998). (See Appendix A for lactose content of various dairy foods.) Dairy Product Consumption and Lactose Intolerance Some studies have indicated self-reported consumption of milk. However, the extent and variation to which individuals with lactose intolerance consume dairy products is not confirmed. Few studies to date have quantified actual consumption of dairy products. Research has shown a positive correlation between milk rejection and lactose intolerance (Bayless et al., 1975). Thirty-one percent of individuals with lactose intolerance did not drink 22 Chapter II: Literature Review milk compared to only 13% of subjects who were lactose tolerant (Bayless et al., 1975). Individuals with lactose intolerance may avoid calcium-rich dairy foods, such as milk, yogurt, and cheese due to symptoms of intolerance following ingestion (Birge, Keutmann, Cuatrecasas & Whedon, 1967; Newcomer, Hodgson, McGil l , & Thomas, 1978; Martini & Savaiano, 1988). Also, individuals with lactose intolerance may limit their intake of milk and dairy products or be counselled to avoid dairy products by peers or health practitioners (Birge et al., 1967; Newcomer et al., 1978; Solomons, Guerro, & Torun, 1985; Martini & Savaiano, 1988; Hertzler & Savaiano, 1996). In one study on lactose intolerance, 10 of 30 participants avoided all dairy products; the remaining 20 participants consumed dairy products with lactose hydrolysing agents (Suarez et a l , 1995). One study from Finland assessed daily mean habitual intake of lactose from dairy products; data were collected using a questionnaire designed to elicit information on normal milk consumption habits. Researchers found that lactose ingestion from milk and other dairy sources was lower among those with lactose intolerance than among a lactose tolerant reference group (4.2 ± 8.4 g/day versus 21.4 ± 12.7 g/day), suggesting that those with lactose intolerance consume smaller amounts of dairy products (Vesa et al., 1996). However, the actual consumption data were not published; furthermore, the diet in Finland is known to include higher levels of milk and other dairy products than other countries (Vesa et al., 1996), thus limiting the applicability of data to the North American situation. Furthermore, the study did not discuss participant recruitment therefore it is possible that the sample was not representative of the population. An Italian study utilized a seven day food record to assess daily consumption of all common foods, including milk and dairy products (Carroccio, Montalto, Cavera, & Notarbatolo, 23 Chapter II: Literature Review 1998). Study participants, who self-reported milk and lactose intolerance and were tested to assess lactose digestion, were classified into three categories: lactose-digesters and lactose tolerant; lactose-maldigesters and lactose tolerant; lactose-maldigesters and lactose intolerant (Carroccio et al., 1998). Participants who digested and were tolerant of lactose (n=98) consumed a mean of 170 mL milk/day, with a range from 0 - 1,700 mL/day. Lactose maldigesters who were tolerant of lactose (n=48) consumed a mean of 165 mL milk/day, with a range from 0 -1,200 mL/day. Participants who maldigested lactose and were lactose intolerant (n=6) showed the least variability, consuming a mean of 50 mL milk/day with a range from 0-100 mL milk/day. This study provided new data on milk consumption in the population of individuals with self-reported lactose intolerance; however, participants were randomly selected from a restricted sample in a small rural Italian population. This may limit the generalizability of data, as participants were selected to reflect the age distribution of the population, and many participants may have been genetically related. More research into the milk and dairy consumption patterns of individuals with lactose intolerance (real and perceived) is therefore necessary. Importance of Dairy Products Milk is the primary calcium source in the North American diet, accounting for more than 55% of calcium intake (Block, Dresser, Hartman '& Carroll, 1985; Fleming & Heimbach, 1994; Mongeau, 1995; Gerrior, Putnam & Bente, 1998; Weaver, Proulx & Heaney, 1999). Correspondingly, dairy products naturally contain the most substantial amount of calcium of all major food sources (Suarez, Adshead, Furne & Levitt, 1998). Individuals with lactose intolerance, i f not consuming dairy products, can potentially meet calcium needs by 24 Chapter II: Literature Review incorporating calcium-rich greens (turnip greens, broccoli, collard greens, Chinese cabbage, kale), bony fish and other lactose-free, calcium-rich foods into their diets. Breads and cereals, while providing relatively low amounts of calcium, are significant contributors to calcium intake as a result of their frequent consumption (Musgrave, Giambalvo, Leclerc & Cook, 1989). However, whether or not calcium needs can be met in diets where non-dairy food sources provide the majority of calcium intake remains open to question. Phytates, oxalates and fibre (constituents in vegetables and grains) bind calcium (Weaver, Heaney, Martin, & Fitzsimmons, 1991; Brown, 1995; Weaver, Heaney, Teegarden, & Hinders, 1996; Kerr, 1999). The binding of calcium decreases its bioavailability and its efficiency of absorption by the small intestine (Miller, 1989; Weaver et al., 1996). A higher calcium intake may therefore be required to meet calcium needs, as bioavailability of calcium was not considered in the setting of the new dietary reference intakes for calcium (Standing Committee on the Scientific Evaluation of the Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine, 1997). The fortification of fluid milk with vitamin D is another consideration for individuals with lactose intolerance who avoid dairy products, as vitamin D metabolites enhance calcium absorption (NIH, 1994; Heaney, Barger-Lux, Dowell, Chen & Holick, 1997). Few foods contain substantial quantities of vitamin D (Clemens & O'Riordan, 1995). Without fortified fluid milk, individuals may not meet the dietary recommendations for vitamin D, especially in winter months at high latitudes, where ultraviolet rays are not strong enough to stimulate endogenous production of vitamin D by the human epithelium (Webb, Kline & Holick, 1988; Haddad, Sabate & Whitten, 1999). Vitamin D is formed by photolyzation of 7-dehydrocholesterol to pre-vitamin D3 in the skin upon exposure to ultraviolet (UV) B radiation (Webb et al., 1988). This is a pre-cursor for 25 Chapter II: Literature Review vitamin D3, which goes on to form the active vitamin D that enhances calcium absorption. However, in the Northern hemisphere during the winter months from November through February, 7-dehydrocholesterol and the skin of individuals residing North of 42.2 degrees latitude do not produce pre-vitamin D3 (Webb et al., 1988). This time frame is extended to October through March in people residing North of 52 degrees latitude. It is suggested that vitamin D is therefore limited in some Canadians, such that diets excluding fortified fluid milk may require vitamin D supplementation to minimize risks to calcium absorption (Webb et al., 1988; Haddad etal., 1999). Some concern has also arisen over the ability of people to meet recommended vitamin D levels during the summer months. Sunlight is a large provider of vitamin D for humans (Webb et al., 1988). Obtaining adequate vitamin D during the summer months should therefore not be problematic, but several researchers have suggested that the use of sunscreens may limit the ability to meet recommended levels (Holick, 1987; Matsuoka, Ide, Wortsman, MacLaughlin, & Holick, 1987). Sunscreens, commonly advocated in the prevention of skin cancer, block the portion of sunlight that is responsible for cutaneous synthesis of vitamin D (Matsuoka, Wortsman, Hanifan, & Holick, 1988; Matsuoka, Wortsman & Hollis, 1990; Holick, 1995; Sollitto, Kraemer & DiGiovanna, 1997). In 1987, Matsuoka and colleagues investigated the effect of sunscreens on the cutaneous formation of vitamin D3 in eight individuals. The individuals were assigned to either a control or experimental group. The experimental group was protected with the sunscreen para-aminobenzoic acid before being exposed to one minimal dose of U V radiation. The control group was exposed to the same dose of U V radiation without the protection of sunscreen. The serum concentration of vitamin D3 rose from 1.5 ± 1.0 to 25.6 ± 6.7 ng/mL in the 26 Chapter II: Literature Review control group, while the serum concentration remained essentially the same in the experimental group who had applied sunscreen. This indicated the interference of sunscreen in the production of vitamin D3 in the skin. Further studies utilizing the same sunscreen found that serum 25-hydroxyvitamin D levels were significantly lower (p<0.001) in long-term sunscreen users than among non-sunscreen users, matched for age and sunlight exposure (Matsuoka et al., 1988). This indicated that fewer vitamin D stores were available to be converted into the active form of vitamin D and that long-term use of sunscreen may be associated with low body vitamin D stores. A study that tracked changes in 25-hydroxyvitamin D in 24 sunscreen users and 19 controls found that mean levels of 25-hydroxyvitamin D levels were significantly lower (p<0.05) in the winter months for sunscreen users than they were for controls (Farrerons et al., 1998). Mean levels rose in the summer for both groups, and levels were significantly higher (p<0.001) in the control group (Farrerons et al., 1998). While the differences in 25-hydroxyvitamin D levels were lower in the sunscreen-using group, the authors of the study concluded that the lower levels observed were minor since changes in parathyroid hormones and bone markers were not observed. However, sunlight exposure was neither measured nor controlled in either of these studies, limiting the accuracy of conclusions that could be drawn, and necessitating further research into the effect of sunscreen use on vitamin D status. Opposing results have also been reported. For example, a study performed in Australia that followed 113 participants over one summer found no significant differences in 25-hydroxyvitamin D levels between sunscreen-using and placebo- using participants (Marks et al., 1995). For individuals with lactose intolerance who choose not to consume milk, living at high latitudes in winter months and regular use of sunscreen may increase the risk of not meeting 27 Chapter II: Literature Review vitamin D needs, thereby potentially compromising calcium status. Careful dietary planning is therefore necessary to meet vitamin D recommendations without dairy products, or supplements may be utilized to attain recommended intakes. The proportion of individuals consuming vitamin D and calcium supplements in Canada has not been widely studied. Nor are recent data available on supplementation amounts or adequacy, increasing the importance of determining patterns and levels of dairy product consumption among individuals with true or perceived lactose intolerance. Adequate Intake Levels for Calcium The Dietary Reference Intakes (DRIs) are dietary intake values that are meant to minimize the risk of developing conditions that are associated with a specific nutrient and that have negative consequences to the health of an individual (Standing Committee on the Scientific Evaluation of the Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine, 1997). The mineral calcium has an Adequate Intake (AI) level of 1000 mg/day for males and females aged 19-50 years and 1200 mg/day for males and females aged 50 years and above (Standing Committee on the Scientific Evaluation of the Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine, 1997). Food and Supplementary Calcium Intake Despite concern for calcium intake, suboptimal calcium intake appears to be widespread (Berner, Clydesdale & Douglass, 2001). Data from the most recent National Health and Nutrition Examination Survey (NHANES III) were collected in the U.S. using a 24 hour recall during 1989-1990 (Alaimo et al., 1994). The results indicated that males and females (of all ages) consumed a mean of 976 mg/day (± 1454 mg/day) and 744 mg/day (± 1038 mg/day) 28 Chapter II: Literature Review calcium, respectively (See Table 2.2) (Alaimo et al., 1994). Overall calcium intake was below the 1989 Recommended Dietary Allowance (RDA) in place at the time of the study, for all Table 2.2: Calcium intake (mg/day) by age-sex as reported in the National Health and Nutrition Examination Survey (NHANES) III, 1989-1990. Age category Gender n Calcium Intake (mg/day) 20-29 m 844 1075 f 838 778 30-39 m 735 1049 f 791 753 40-49 m 626 834 f 602 685 50-59 m 473 854 f 456 651 60-69 m 546 875 f 560 711 70-79 m 444 808 f 407 636 80+ m 296 721 f 313 626 A l l ages m 7322 976 f 7479 744 Reproduced from NHANES III study, Alaimo et al., 1994. 29 Chapter II: Literature Review groups except males age 20-39 (National Research Council, 1989). Calcium intake of males (mean and median) was significantly higher than females. More recent Canadian data from 1997-1998 appear to follow similar trends as in the U.S. Data were collected using a 24 hour recall similar to that used in the NHANES III study; the method was considered appropriate given the large group of individuals, and the collection of data spanning all seasons, days of the week and weekend (Gray-Donald, Jacobs-Starkey, & Johnson-Down, 2000). Similar to U.S. data, mean intake of calcium was below the current Adequate Intake level for most groups (Gray-Donald et al., 2000). (See Table 2.3). Women in particular were noted to consume substandard levels of calcium (Gray-Donald et al., 2000). Current U.S. data indicate a critically high risk for calcium intake below the recommendations in the population, especially those aged 51 years and over (Foote, Giuliano & Harris, 2000; Pfister, Wulu & Saville, 2001). This risk remained high even when supplementary calcium intake was included. Furthermore, a study on the trends in the use of mineral supplements in the U.S. indicated a decrease in calcium use from 6.2% to 4.9% between 1987 and 1992, although the authors concluded that this was not a meaningful change (Slesinki, Subar & Kahle, 1995). In Foote and colleagues' study, 15% -17% of male and female older adults (aged 51-70) and 11-16% of male and female older adults (aged 71-85) met their calcium recommendations. Study participants consumed an average of 1-1.3 servings of dairy products daily (Foote et al., 2000); lower than the four servings of milk and dairy products (approximately 300 mg calcium per cup) or the equivalent thereof that would be required each day to meet the 1200 mg/day AI for adults aged 51 and older (Soliah, 1999). Canadian male and female older adults (aged 50-65) consume 1.5 and 1.3 servings per day, respectively (Gray-Donald et al., 2000). In both Foote and colleagues study of older adults and Gray-Donald and colleagues' 30 Chapter II: Literature Review Table 2.3: Calcium intake (mg/day) by age-sex as reported in Food Habits of Canadians study, 1997-1998. Age Group Gender n Mean calcium intake (mg) 18-34 m 125 1375 f 207 875 35-49 m 266 1020 f 459 764 50-65 m 181 901 f 306 777 Reproduced from Food Habits of Canadians study, Gray-Donald et al., 2000. study, the inability of the majority of participants to meet their Adequate Intake (AI) of 1200 mg/day (Standing Committee on the Scientific Evaluation of the Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine, 1997) from food intake alone confirms the importance of dairy foods in meeting calcium needs of the population. This reinforces the need for efforts to encourage calcium intake, and further assess calcium intake of individuals not consuming dairy products. Additionally, it confirms the suggestion that individuals with lactose intolerance who exclude dairy products may be at further risk of consuming calcium below the recommended intakes. 31 Chapter II: Literature Review As previously mentioned, little research has been performed to assess the proportion of individuals consuming vitamin D and calcium supplements in Canada. One population-based study exploring Canadians' concerns for nutrition in 1997 indicated that 67% of the Canadian population were concerned about calcium intake (NIN, 1997). In the study, one in three Canadians reported consuming supplements as a result of their concern for calcium intake. Individuals over the age of 55 were the most likely to take calcium supplements, while respondents under age 35 were more likely to be drinking milk to attain calcium (NIN, 1997). Reports of supplement use are positive, as vitamin and mineral supplements are considered increasingly important since dietary practices have changed over many years to reduce vitamin and mineral delivery in the diet (Welsh & Marston, 1982; Balluz, 2000). The use of fortified beverages (e.g., orange juice, soy and rice beverages) in providing dietary calcium remains largely unexplored. Other fortified foods may also contribute to total calcium intake. Fortification data from the Continuing Survey of Food Intakes by Individuals (CSFII) study indicate that calcium fortified foods are consumed by 5% of the population, without influencing calcium intake (Berner et al., 2001). However, this study was conducted prior to the widespread introduction of fortified foods in the U.S. diet. Seventy-six percent of the study population met the 1989 R D A for calcium intake when fortified foods were included and excluded (Berner et al., 2001). The current contribution of fortified foods to total calcium intake is unclear at present, as the proportion of individuals consuming calcium-fortified foods may be different today. Given the recent availability of calcium fortified foods and beverages (e.g., mainstream items such as fortified orange juice, rice and soy beverage) in the Canadian marketplace, the consumption of such items and their contribution to calcium intake should be explored. 32 Chapter II: Literature Review Attitudes Attitudes may play a role in consumption or avoidance of milk and dairy products. In British Columbia, the overall consumption of milk is more limited when compared to the national average (Commins & Wingrove, 2000). Research has indicated that adults living in British Columbia tend to have more negative attitudes towards milk than the average Canadian adult (Commins & Wingrove, 2000). Correspondingly, 23% of British Columbians agree that negative reports of milk are reported frequently in the media, compared to 18% nationally. When looking at specific concerns with regards to milk, 59% of BC residents agreed that cows are treated with growth hormones, compared to 46% nationally. Of interest was the indication that in British Columbia, adults with lactose intolerance or other health concerns related to milk held more negative opinions of milk, and were more likely to limit milk consumption when compared to the national average. Seventy-seven percent of the BC population believed calcium could be obtained from sources other than milk, and 25% limited their milk consumption because of this belief compared to 16% nationally. In the media, greater attention to calcium has led to greater awareness of needs and calcium sources. Combined with attention to milk and dairy products, attitudes may continue to play a large role in milk and dairy consumption. Attitudes therefore need to be explored, particularly in relation to lactose intolerance. 33 Chapter II: Literature Review Information Sources Some authors have established that patients with abdominal complaints focus on foods that have received extensive media attention as causes of abdominal distress, e.g., dairy products (lactose) (Suarez & Levitt, 1996). Another issue pertinent to lactose intolerance is therefore information provided by news-media sources. Anti-dairy advocates, Internet newsgroups and popular magazines have promoted negative perceptions and misperceptions about the Canadian dairy industry and its products. Some sources include the Adbusters Website (1999), Anti-Dairy Coalition Website (2000), Crohn's Disease and Milk Research Website (2000), Milk Sucks Website (2000) and the vegan book "Diet for a New America" (Robbins, 1987). These anti-dairy campaigns may be promoted partly because of perceived hormone and antibiotic use by the dairy industry. Anti-dairy campaigns based on the controversial use of antibiotics in cows also perpetuate misperceptions, because by law, milk is to be residue free i f it is to enter the food chain (Canadian Food Inspection System, National Dairy Code, 1997). Problems with promoting misperceptions arise from the multi-national origins of the groups because statements are not qualified according to the different laws in the countries where promotions are aimed. Other anti-dairy campaigns try to link dairy products (specifically milk) to medical conditions, such as acne, allergies, diabetes, cancer, multiple sclerosis, osteoporosis, and to social problems such as juvenile delinquency (Anti-Dairy Coalition Website, 2000; Crohn's Disease and Milk Research Website, 2000). Quotes and paraphrases from scientists, physicians and naturopaths may lend credibility to their ideas and articles in the eyes of consumers untrained to critically analyze data or claims presented. According to the Diffusion of Innovation Theory (Rogers, 1995), individuals will be wary of new technologies. The adoption of behaviour, or in this case a belief, spreads through a 34 Chapter II: Literature Review community from opinion leaders (early adopters) to later adopters. Scare-tactics can be used by opinion leaders to promote fear of unknown side-effects in humans as a result of perceived growth hormone use in cattle. Adbusters Media Foundation, the foundation that publishes Adbusters Magazine and maintains the Adbusters website, is a certified non-profit society that generates social marketing initiatives to raise awareness for various causes and to stir public debates. The foundation has become a "thought leader" for an alternative culture that argues for fundamental social change, sharing information through bases in both Vancouver BC and Blaine, W A (U.S. A). A recent social marketing initiative has focused on the perceived use of growth hormones and antibiotics, as well as the artificial pregnancy induced in dairy cattle to enhance milk production. The campaign utilized "spoof-ads", spin-offs of advertisements for milk, to promote soy beverage and demote cows' milk on the basis that it is unsafe due to perceived hormone and antibiotic use by the dairy industry. While public communications such as advertising lack accuracy (Shuchman & Wilkes, 1997), they reach the public and affect behaviours (Bell, Kravitz & Wilkes, 1999) because communication is both central and peripheral to attitude and behaviour change (Petty & Cacioppo, 1986). Although this is seen selectively (Bell et al., 1999), media attention (publicity) to lactose intolerance and high-profile advertisement for lactose digestive aids may have convinced many people that they are lactose intolerant (McBean & Miller, 1998), and may be influential in encouraging negative attitudes towards milk and dairy products. One hormone receiving such attention is recombinant bovine somatotropin (rbST). RbST is a biosynthetic version of a naturally occurring growth hormone that emerged as an instrument of animal technology in the early 1990s (NIH, 1990; Bauman, 1992). It is used to increase milk production 10-15% in dairy cows (McGuffey & Wilkinson, 1991; Bauman, Everett, Weiland & 35 Chapter II: Literature Review Collier, 1999) by facilitating metabolic changes that enhance the utilization of nutrients for the synthesis of milk (Bauman, 1992), and by improving persistency of production (McGuffey & Wilkinson, 1991). RbST was approved for use in dairy cattle in the United States after a review of research concluded that rbST supplemented animals remain normal and healthy, and that milk composition (including calcium and hormone residues) remained unchanged (Daughaday & Barbano, 1990; NIH, 1990; Bauman, 1992). Considerable controversy and public interest have been raised over rbST use, and the possible adverse health effects from the consumption of milk and other dairy products from rbST-stimulated dairy cows (Etherton, 1990; NIH, 1990; Gougeon & Taveroff, 1994). Concerns have been raised over the possible growth and carcinogenic effects of rbST action in the human body, and consequences for supplemented animals. After nine years of review, Health Canada formed two panels to determine the safety of rbST for humans and animals: the Canadian Veterinary Medical Association (CVMA) Expert Panel on Safety of rbST and the Royal College of Physicians and Surgeons of Canada (RCPSC) Expert Panel on Human Safety of rbST. The expert panel discussing human safety of rbST concluded that rbST did not pose a risk to the health of Canadians (Health Canada, 1999). Research adequately indicates that rbST is degraded to single amino acids by the combination of gastrointestinal enzymes and acidity, and is structurally different from human growth hormone (Health Canada, 1999). For these reasons, rbST has no biological activity on human growth receptors or in humans, and poses no risk of carcinogenicity (NIH, 1990; Juskevich & Guyer, 1990; Health Canada, 1999). The Canadian Veterinary Medical Association Expert Panel concluded that rbST presented some unacceptable risks to dairy cattle that could not be overcome by management practices, and had some effects for which evidence was inconclusive and required further research (Health Canada, 1998). 36 Chapter II: Literature Review While the U.S. National Institute of Health (NIH) has accepted milk from rbST supplemented cows as safe for humans, Health Canada has not approved rbST for use in the Canadian dairy industry due to animal health concerns (NIH, 1990; Health Canada, 1999). Public perception is a critical factor in defining the importance of rbST. Consumers in North America are exposed to both American and Canadian media. The divergent regulations for rbST between Canada and the U.S.A. are not well documented and therefore consumers may be exposed to misleading and conflicted advertising on both sides of the border. In 1999, a questionnaire administered to a convenience sample of premenopausal, vegetarian and non-vegetarian adult women in Vancouver, used a Likert-type scale to assess beliefs held about dairy products. The results indicated that 26.5% - 51.4% of individuals in Vancouver believe that dairy products contain unnatural hormones (Barr, 1999; Barr & Chapman, 2002). Forty-eight percent (43/90) of vegetarians, 51.4% (17/35) of past vegetarians and 26.5% (18/68) of non-vegetarians agreed or strongly agreed that dairy products contained hormones. While the questionnaire did not specify rbST as an example of a hormone, it is possible that people interpreted the question this way. A similar issue is the public perception of antibiotic use in the dairy industry. In the same study referred to above, 50.6% (n=46/90) of vegetarians, 45.7% (n=16/35) of past vegetarians and 19.4% (n=l 3/68) of non-vegetarians believed that dairy products contain antibiotics (Barr, 1999; Barr & Chapman, 2002). This constitutes a misperception that is present among members of Canadian society. Disease and infection control is integral to the management of dairy herds, and antibiotics play an important role in herd health management (Fisher, Wetzstein, Shelford & Dyble, 1998). However, antibiotic treatment in lactating cows is regulated because of antibiotic residues in 37 Chapter II: Literature Review milk. In 1998, Fisher and colleagues confirmed that antibiotic treatment in lactating cattle results in the secretion of antibiotic residues that can be detected in milk up to 48 hours after the last antibiotic injection (Fisher et al., 1998). In cases of extra-label antibiotic administration (doses that are higher than legally accepted) residues may be detected 120 hours after last injection because extra-label administration results in longer and unpredictable secretion times (Fisher et al., 1998). Antibiotics may be used in animal feeds, as well as for treatment of infection or illness. Use of antibiotics in feeds is limited to those that are licensed by the Bureau of Veterinary Drugs and standard amounts are prescribed accordingly (Canadian Food Inspection Agency, 2002). The use of antibiotic containing feeds may cause antibiotic residues to appear in the milk (Kennedy, 1960). While the addition of antibiotics to feeds is commonly used in chicken or hog production, the practice is less feasible for milk-producing cows. Cows that consume antibiotics in feed at a level high enough to allow secretion of residues into milk have reduced food intakes and milk production due to alterations in ruminant flora (Fisher et al., 1998). The presence of antibiotic residues in milk can inhibit the fermentation processes used in yogurt and cheese processing (Fisher et a l , 1998). Accordingly, feeds for dairy cattle do not contain antibiotics. The identification of antibiotic residues in milk is a potential risk for negative consumer reactions, and constitutes a violation of Canada's National Dairy Code (Canadian Food Inspection System, National Dairy Code, 1997). The Code outlines additional strict standards for the presence of veterinary drug residues to avoid contamination of milk, processed dairy products, and subsequently, the human food chain. To avoid injury to human health, regulations require that milk from cows that are being administered antibiotics be withheld until milk samples are residue free. The code also requires that milk, sampled using prescribed methods at 38 Chapter II: Literature Review the time of transport to a dairy processing facility, must be free of all veterinary drug residues to be accepted for entry into the food chain (Canadian Food Inspection System, National Dairy Code, 1997; Canadian Department of National Health and Welfare, Food and Drugs Act, 1999). It is important to recognize, however, that "residue free" is a relative term. That is, sampled milk must be free of veterinary drug residues within limits prescribed by the Canada Food and Drugs Act and Codex Alimentarius (Joint FAO/Codex Alimentarius Commission, 1995). These range between 4 and 500 ug/L of milk. Rejection of milk due to antibiotic residues is costly to the producers of contaminated milk, who will be fined if milk contains residues above regulated levels when sampled. The elimination or minimization of residue contamination is therefore of paramount importance to dairy producers (Fisher et al., 1998). Because antibiotics are controlled in dairy production in Canada, the idea that dairy products contain antibiotics should not be prevalent, and should not constitute a problem. However, in recent years, there has been an increase in media attention expressing the concern that antibiotic use in animals may create a human health risk through bacterial resistance. Attention has also been paid to the fact that, while consumers increasingly demand zero tolerance for residues in milk, testing kits only detect certain levels of antibiotic residues (Sischo, 1996). Detection levels vary between testing methodologies, and while some kits approach zero levels, other do not. It is therefore the limitations of testing methodologies that set the limits for residue free milk. The knowledge of testing limits for drug residues may increase consumer concern over antibiotic use. With antibiotics receiving increasing attention through news-media, and increasing use of the Internet (where news articles know no borders and are more subject to personal bias), antibiotics have become an issue for Canadian consumers. The "knowledge" expressed by 39 Chapter II: Literature Review Canadians about antibiotic or perceived hormone use in the dairy industry may be based on media-influenced negative attitudes towards antibiotic use or on feelings of unease over the use of hormones to stimulate milk production. It is plausible that these anti-dairy sentiments are spreading and as a result more individuals are choosing not to consume milk and other dairy products. The discontinuation of dairy product consumption may be a concern for calcium intake, although recent Canadian national survey data for calcium intake are not currently available (Standing Committee on the Scientific Evaluation of the Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine, 1997). Methods in the Literature In the literature that has tried to establish calcium, dairy product and lactose consumption in people with lactose intolerance, researchers have used a variety of assessment tools. For dairy product and lactose consumption, researcher-developed questionnaires and food frequency questionnaires have primarily been used as assessment tools. Many have been as simple as questioning participants to recall their milk consumption. The assessment of calcium intake has received much wider attention, and assessment tools are correspondingly diverse. Because the accuracy of estimates for energy, vitamin and mineral intakes are important in the assessment of dietary status, and because day to day variability adversely affects estimation accuracy (Basiotis, Welsh, Cronin, Kelsay & Mertz, 1987), many assessment methods have been tested, interpreted and validated. The 24-hour recall method is a method that was designed to quantitatively assess recent nutrient intake (Barrett-Connor, 1991). While expensive, it is not the most expensive method available for use, and has the advantage of accuracy, since most people can remember what they ate yesterday. The method has a major disadvantage: it is not representative of an individual's 40 Chapter II: Literature Review usual diet (Barrett-Connor, 1991). Also, since it provides a "snapshot" of nutrient intake, it is inadequate for assessing deficiencies, as diets vary day to day. In the early 1980s, duplicate plate collection assessment was considered the "gold standard" (Mertz, 1992). Doubts about the methodology were raised when a series of results indicated that most mineral values using this assessment methodology were consistently in negative balance, without any positive adaptation (Mertz, 1992). Since this would have resulted in severe deficiencies, and no deficiencies were observed, duplicate plate collection was found not to be representative of habitual intake. During the same period, values from national survey data comparing weight with estimated food consumption indicated that weight gain in participants was contradicted by a reported decrease in caloric intake (Mertz & Kelsay, 1984). The Beltsville one year dietary intake study was designed to determine the representativeness of duplicate plate collection. In this study in which participants kept detailed daily records of intake for a year, duplicate plate collection records were kept for four separate one week periods, and compared to the yearly mean, and the weeks preceding and following plate collection. Research results indicated that underreporting or alterations in food intake were likely to have occurred during the recording period. Significant reductions were found for all nutrients during the duplicate plate collection recording period; energy, protein and fat intake were reduced 12.9%, 14.9% and 12.9%, respectively (Kim et al., 1984). The Beltsville study therefore confirmed that such methods were inaccurate as participants were demonstrated to eat less during the weeks that duplicate plate records were collected (Kim et al., 1984). Several authors have continued research into assessment methods used to represent usual intake. In a study performed to determine the number of days of food intake records required to provide a "true" estimate of average nutrient intake with a known confidence interval, Basiotis 41 Chapter II: Literature Review and colleagues (1987) studied food intake records for one full year for each of 29 research participants. A "true" estimate was defined as falling within 10% of true average intake with a 95% confidence interval. For individual nutrient intake, the number of days needed to fulfill this requirement ranged from 14 to 1724 days. For group nutrient intake, where n=29, the number of days ranged from three to 44. (These figures can be adjusted by altering the group size). For calcium intake in individuals, the average number of food record days needed to accurately estimate intake was 74 days for males, and 88 days for females (Basiotis et al., 1987). As a group, (n=29) only 10 days and seven days would be needed, respectively, for males and females. These results suggest that food records have the potential to provide information that is precise and accurate, but for individuals this potential is often limited by the prohibitively large number of records that must be obtained. While dietary intake records have the potential to provide accurate and precise information i f used in long term studies, cost, time and participant compliance decrease their acceptability to administer to large populations (Barrett-Connor, 1991). Food frequency questionnaires are used commonly in these situations due to their quick administration, and relative ability to address longer-term intake patterns (Bergman, Boyungs, & Erickson, 1990). Food frequency questionnaires are not necessarily accurate for long-term intake as they may overestimate or underestimate intake in comparison to food records. In 1995, a study comparing calcium intake assessed by food frequency questionnaire in comparison to seven day food records, found that calcium intake measured using a 19 item food frequency questionnaire was significantly less (p<0.001) than that measured by seven day food records (Taitano, Novotny, Davis, Ross & Wasnich, 1995)! However, several large studies have found food frequency questionnaires to be valid measures of nutrient intake (Angus, Sambrook, Pocock & Eisman, 42 Chapter II: Literature Review 1982; Cummings, Block, McHenry, & Baron, 1987). Angus and colleagues (1982) found that a food frequency questionnaire designed to measure calcium intake estimated slightly lower values for calcium intake than did four day weighed food records, but analysis found a correlation coefficient of r=0.79 (p<0.001). This study indicated that the use of a questionnaire to assess calcium intake could be markedly simple yet be sufficient to ensure reasonably accurate data (Angus et al., 1982). In a later study, Musgrave and colleagues (1989) reported a correlation coefficient of r=0.73 in winter and r=0.84 in summer for calcium estimated from their questionnaire in comparison to four day records. While these studies were validated in comparison to methods that can be questioned for validity themselves (Block, 1982), no food and nutrient assessment method is perfect. Thus, the proposed research will utilize questionnaires, including a short food frequency questionnaire to assess intake of dairy products and calcium. Research has established that the listing of the food items in a food frequency questionnaire may influence respondents (Barrett-Connor, 1991). For example, listing dairy products first in a list may distress individuals with lactose intolerance. The B.C. Dairy Foundation accounted for this when developing the Calcium Calculator™. Evaluation of the instrument indicated that respondents were comfortable with the listing of foods in the order that they were presented, and were thus able to complete the Calcium Calculator™ activity (B.C. Dairy Foundation, 2000a). The food frequency questionnaire to be used for the proposed study will follow the order presented by the B.C. Dairy Foundation in their Calcium Calculator™ tool. Additionally, food frequency questionnaires are generally thought to be culture specific (Barrett-Connor, 1991). Efforts will therefore be made to include major calcium sources from a variety of cultures. Chapter II: Literature Review Purpose The focus of this proposed research will be on individuals with self-reported lactose intolerance. These are individuals who report that they are lactose intolerant based on their perceptions of lactose intolerance, regardless of whether or not they actually experience the typical symptoms (stomach bloating, cramps, gas and/or diarrhea) after ingestion of milk and other dairy products. Because previous studies on lactose intolerance have identified that more individuals claim to be lactose intolerant than actually are, the target group for this proposed research will include some people with true lactose intolerance (symptomatic lactose maldigestion), some lactose tolerant maldigesters, and some lactose digesters. Among individuals with self-reported lactose intolerance, the purposes of this descriptive study are to: 1. determine the completeness of knowledge regarding lactose intolerance 2. determine attitudes towards milk and dairy products 3. determine diagnostic characteristics 4. assess consumption patterns of dairy products and other calcium sources 5. identify major sources of information regarding lactose intolerance. 44 Chapter III: Methodology Methodology Overview This study was an exploratory survey design administered to self-selected study participants. A questionnaire was developed for the study, and pre-testing and reliability testing of the data collection instrument occurred during December 2000 - February 2001. Data were collected from March 2001 - June 2001. Participants were recruited from the Greater Vancouver Regional District using recruitment posters and advertisements (Appendix B). Ethical review was obtained prior to participant recruitment and testing (Appendix C). Confidentiality was maintained by the use of code numbers in replacement of names or other identifying features. Questionnaire Development Instrument Description/Items Included The instrument used in this study was a questionnaire (Appendix D) developed by the primary investigator in consultation with the thesis committee. The questionnaire was based on different categories of literature reviewed, including: attitudes towards milk and dairy products, clinical symptoms of lactose intolerance, symptomatic response to dairy food items, and assessment of calcium intake. Response options to individual survey items were established from published literature. The questionnaire consisted of seven major components as follows, i . Demographics Standard questions were presented in order to provide descriptive information on study participants. Demographic data included age, education, ethnicity and gender. Data on participant ethnicity were collected using the standards set by the Canada 2001 census form (Statistics Canada, 2001). 45 Chapter III: Methodology i i . Food Frequency Questionnaire and Calcium Supplementation In order to assess calcium intake, a food frequency questionnaire and a question grid to assess use of calcium supplements were included in the survey instrument. The food frequency questionnaire was developed by adapting the Calcium Calculator™ (developed by the BC Dairy Foundation to elicit information on the previous days' intake and as an educational tool to help individuals plan dietary changes). Food frequency questionnaires can provide a more long-term estimate of calcium intake than other methods used to assess intake, including the previous days' dietary recall as used in the Calcium Calculator™ (Bergman et al., 1990). In order to convert the Calcium Calculator™ to a food frequency questionnaire, the tool was reformatted to a grid-like tool with columns to reflect daily, weekly and monthly intake instead of intake from the previous day. A "do not eat" column was also provided as an option. An example of how to complete the questionnaire was provided to aid comprehension. i i i . Vegetarianism A series of questions were posed to determine participants' vegetarian status. Participants were asked about current and previous vegetarian habits, and food avoidances. Questions were presented according to the format developed by Janelle & Barr, 1995. iv. Diagnosis, Symptoms and Severity of Lactose Intolerance Both open and closed ended questions were used to determine method of diagnosis and tests used in diagnosis (if any). Perceived symptoms and severity of intolerance were also assessed. An open-ended question was used to elicit perceived symptoms 46 Chapter III: Methodology of lactose intolerance to determine the variety of symptoms that participants associate with lactose intolerance. v. Knowledge and Attitude Scales A series of statements pertaining to lactose intolerance and to milk and dairy products were used to identify both participants' knowledge of lactose intolerance and attitudes towards dairy products. Items pertaining to knowledge were combined to form a knowledge scale; similarly, items were combined to form a separate scale for attitude. [See data analysis section for details of scale construction and coding.] Knowledge The knowledge scale was comprised of 12 statements pertaining to lactose intolerance. The first sub-section of the scale questioned participants' knowledge of the physiology of lactose intolerance. Statements were developed from literature based knowledge of lactose intolerance. The second sub-section of the scale referred to symptoms of lactose intolerance; the symptoms used in this section were taken from research literature outlining true symptoms of lactose intolerance (Villako & Maroos, 1994). Symptoms that do not indicate lactose intolerance, but that are commonly reported side effects of many conditions or medications in research (e.g., headache, weight gain) were also included so that true symptoms were not the only ones presented. The final sub-section questioned participants with regards to their knowledge of lactose in foods and whether or not lactose-containing foods can be maintained in the diet, as some literature sources indicate that intolerance should not preclude consumption of milk and dairy products for attaining calcium needs (Suarez etal., 1998). The knowledge scale used a three-point response option. Participants 47 Chapter III: Methodology were able to record answers as true, false, or unsure. [See data analysis section for details of scale construction and coding.] Attitudes A series of eight statements were used to comprise the attitude scale. Statements were chosen from select literature, although not all were presented in their original form. Some statements were reversed to form negative or positive statements. (For a full list of statements and their original references, please see Appendix E). Statements included references to the use of hormones in cows and the presence of hormones and antibiotics in milk. A similar statement referred to perceived contamination of milk and dairy products. The statements were used directly, or in an adapted form, from their original version in a study on barriers to milk consumption (Commins & Wingrove, 2000). Other statements questioned participants about their perceptions of dairy products as sources of calcium, as natural foods, and their role in a healthy diet. Additionally, one statement referred to participants' perception of ease of obtaining adequate calcium without including dairy products in their diet (Barr, 1999). Participants' responses were categorized a five point Likert scale used to measure attitude. [See data analysis section for details of scale construction and coding.] vi. Intake and Discomfort Scale Participants were asked to identify whether or not they experience discomfort (symptomatic response) to a variety of foods containing milk and dairy products. In an effort to distinguish the possibility of perceived discomfort, a series of 12 food items presented in the scale contained various levels of lactose; some food items 48 Chapter III: Methodology presented were chosen to reflect previous research on perceived symptomatic response (Vesa et al., 1996). Participants were asked to respond "yes" "no" or "never use" using a closed-ended format, presented in columns. [See data analysis section for details of scale construction and coding.] vii . Information Sources and Learning Issues Surrounding Lactose Intolerance A list of 11 information sources were presented and participants were asked to identify which sources they had used to learn about lactose intolerance, and which sources were helpful. The list was developed to cover comprehensive resources, including media, personal and medical sources of information. Participants were also asked to identify which sources they would use in the future to gather further information about the condition. Furthermore, participants were asked whether they wanted more information on each of five topics related to lactose intolerance. Pre-Testing A convenience sample of 12 participants (seven self-reported lactose intolerant participants and five nutrition professionals) was recruited for questionnaire pre-testing. Participants were asked to complete the questionnaire, followed by an open-ended list of questions (Appendix F) to assess the questionnaire's ease of completion, clarity of the questions asked, and comprehension of instructions. No statistical analyses were performed. Questionnaire pre-testing indicated an appropriate level of comprehension by participants, and led to some minor wording alterations that were incorporated to improve the clarity and utility of the questionnaire, resulting in the preparation of a finalized survey instrument for reliability testing and data collection. 49 Chapter III: Methodology Assessment of Reliability The purpose of the reliability test was to determine the reproducibility of the self-administered questionnaire in individuals with self-reported lactose intolerance. Reliability and validity were previously established for the Calcium Calculator™ items used as the basis for the food frequency questionnaire in the survey instrument. High positive correlation coefficients between three-day food records and the Calcium Calculator™ tool have been reported; details are presented in Appendix G (John Pilgrim, RDN, personal communication, 2002; Eileen Hogan, PhD, personal communication 2001). However, the reliability study did not specifically include a reference group with lactose intolerance. Furthermore, the Calcium Calculator™ was altered to a food frequency questionnaire format for the purposes of this study. It was therefore important to re-establish reliability of the food frequency questionnaire (Calcium Calculator™) items and the survey instrument as a whole using a test-retest reliability design. Validity studies were not undertaken given the time constraints of the study. A convenience sample of 15 self-selected participants was recruited to complete the questionnaire twice at a one-week interval. Twelve of the 15 participants completed the study protocol; two participants did not meet inclusion criteria and one participant did not complete the second questionnaire. Test-retest reliability was assessed using Pearson's product moment correlation and scale internal consistency was assessed using alpha-reliability statistics. Scales measuring knowledge, attitude and behaviour achieved acceptable alpha-reliability coefficients (range 0.85-0.91) and product moment correlations (range r = 0.83-0.96, p<0.01). The food frequency questionnaire for calcium intake achieved a test-retest correlation of r = 0.97,/><0.01. (Details of the reliability 50 Chapter III: Methodology test are presented in Appendix H.) Reliability testing therefore indicated that the questionnaire was an appropriate tool to explore self-reported lactose intolerance. Survey Administration Subjects - Inclusion Criteria The proposed sample size for this study was 150 individuals with self-reported lactose intolerance. This was considered an adequate sample size to provide viable descriptive information of the population of interest, given the expected variety of individuals with self-reported lactose intolerance. (The use of self-reported lactose intolerance allows the inclusion of some people with true lactose intolerance (symptomatic lactose maldigestion), some lactose tolerant maldigesters, and some lactose digesters.) Eligibility was based on the following criteria: 1. Participants were over the age of majority (> 19 years of age). 2. Participants were able to speak and write in the English language. 3. Participants self-reported lactose intolerance (any means of diagnosis: e.g., self diagnosed, diagnosed by a physician, registered dietitian, or naturopath/homeopath). 4. Individuals with Crohn's disease or coeliac disease were excluded because lactose intolerance may occur as a sequela to these diseases. Recruitment Participants were self-selected for this study by responding to recruitment advertisements, constituting a convenience sample. Participants were recruited using advertisements (Appendix B) in a variety of news media to attain circulation to a wide variety of 51 Chapter III: Methodology individuals in the Lower Mainland of British Columbia. Only individuals residing within the Greater Vancouver Regional District (GVRD) were selected to participate. Advertisements appeared in U B C Reports, The Vancouver Sun, The Province, The Westender, and The Link newspapers. More than 200 recruitment posters were placed in various locations around Greater Vancouver, including community centres, grocery stores, and other high access public buildings. Individuals who were interested in the study and who met the inclusion criteria were sent the survey instrument (questionnaire). An opportunity to discuss the study with the primary investigator was provided to potential participants wanting further information prior to enrolment in the study. Participants were informed in writing that the completion of the questionnaire, and its subsequent return represented informed consent to participate in the study. Procedures The survey instrument was self-administered in an environment chosen by the study participant, mostly likely the home. In the first stages of recruitment, participants saw study advertisements in any of a number of city-wide or province-wide publications, or recruitment posters. Participants who responded to the advertisements listened to a recorded message that outlined the study and eligibility criteria. The recorded message asked callers to leave a mailing address (if interested in the study) so that the survey instrument could be mailed out. Alternately, the recording asked for a name, phone number and convenient time for the participant to be contacted, should the participant wish further details about the study. The message posted was as follows: "Thank you for your interest in our study on lactose intolerance. Participation in this study will involve completing a questionnaire about your experience with lactose intolerance. The questionnaire will take approximately 20-30 minutes to complete. If you are 19 years of age or older, experience lactose intolerance, and you are willing to 52 Chapter III: Methodology participate in this study, a package will be sent to you. You are not eligible i f you have Crohn's disease or coeliac disease. This package will include the questionnaire, and a stamped, addressed envelope for the return of the questionnaire. After the beep, please leave your name and full mailing address so that a package can be sent to you. Please speak slowly — and we would appreciate it i f you could repeat your name and address so that we can be sure to get it. If you would like more information about the study before deciding to take part, please leave your name, phone number and a time that would be convenient for someone to phone and further discuss the study with you. Thank you." Callers who provided mailing information received the questionnaire and a return envelope in the mail. The questionnaire and return envelope were labelled with a code number so that data were effectively managed while maintaining participant confidentiality. (The code number was checked off when a survey instrument was returned). A cover letter (approved by the U B C ethics committee, see Appendix I) was included in the packet, indicating that consent to participate in the study was reflected by completing and returning the questionnaire. The letter also indicated that a summary of research results would be made available to all participants upon completion of the study. A reminder notice was distributed to all participants who did not return the questionnaire within three weeks of the date that the initial package was sent. For surveys not returned within three weeks after the reminder notice was sent, another full survey packet was distributed with a note indicating that the survey was important, and that another one was sent in case the first one was misplaced. It was assumed that the participant was no longer willing to continue with the study if the survey was not returned after this mailing. In the third phase of the study, participants returned the questionnaire to the researcher using the included pre-paid, addressed envelope. At this time, a letter was sent to indicate that the completed questionnaire was received and to thank the individual for their participation. Further contact between the researcher and the participant occurred when a summary of research 53 Chapter III: Methodology findings was distributed upon completion of the research, as indicated on the explanatory letter that accompanied the questionnaire. Data Management Data Entry, Cleaning and Verification Data were collected using the survey instrument. Questionnaires and postage pre-paid envelopes were labelled with code numbers, and the investigator maintained a master list of code numbers. Code numbers were used to identify which participants returned the survey instrument, and which participants required reminder notes to be sent, without breaking the confidentiality of responses. Data from the questionnaire, as completed by the study participant, were coded and checked before entry into the SPSS version 10 statistical environment (SPSS Inc., Chicago, Illinois) for data management and analyses. Data codes for closed ended questions were established during questionnaire development. Coding of data from open-ended questions of the survey instrument was completed in two phases established prior to data entry. Participant responses were considered verbatim and categories were created from a collection of similar responses. Data codes were assigned to each category and then used to code actual participant responses for entry into SPSS. Prior to conducting statistical analysis, all data entered into the SPSS file were cleaned: manual verification of entered data was completed to ensure that data in SPSS matched physical data on questionnaires. This was followed by an examination of frequency statistics for data outside the specified range of data for each variable; all identified errors were corrected. 54 Chapter III: Methodology Scale Construction Scales were constructed to assess knowledge, attitude and discomfort behaviour. i . Knowledge Twelve statements were used to determine participants' knowledge of lactose intolerance. Scores for each of the statements were summed to provide a total score for knowledge. Response options for the statements were coded as follows: true (1), false, (-1), Unsure (0), allowing possible scores to range from (-) 12 to (+) 12. A high positive knowledge score therefore indicated a greater level of knowledge held. i i . Attitude A series of eight statements were used to assess participants' attitudes towards milk and dairy products. In order to minimize bias, statements used to construct the attitude scale included an equal number of negative and positive attitude statements. Participants' responded to statements using a five point Likert scale. Response options for the Likert scale and coding were as follows: strongly disagree (1), somewhat disagree (2), neutral (3), somewhat agree (4), or strongly agree (5). To construct a scale, responses for all variables in the scale were summed, requiring recoding of statements to reflect either all positive or all negative attitude statements. A positive attitude scale was developed: responses to all statements reflecting negative attitudes were reverse scored using the "compute" function of SPSS, where 5 =1, 4=2, 3=3, 2=4, 1=5 for negative statements. See Table 3.1. A high attitude score thus indicated a more positive attitude towards milk and dairy products. 55 Chapter III: Methodology Table 3.1: Scoring of statements included in attitudes to dairy products scale. Attitude Statement Attitude Scoring for Scale Assessment Milk and dairy products are good sources of calcium. Positive 1-5 Milk and dairy products are an important part of a Positive 1-5 healthy diet. Milk and dairy products contain synthetic hormones Negative 5-1 (BST or BGH).* Milk and dairy products are natural foods. Positive 1-5 Cows are being treated with growth hormones.* Negative 5-1 Milk and dairy products do not contain antibiotics. Positive 1-5 It is easy to get enough calcium without using milk or Negative 5-1 dairy products.* I think that milk may be contaminated in some way.* Negative 5-1 * Scores for these items were transformed after data entry. Note: The statement "It is easy to get enough calcium without using dairy products" cannot truly be classified as either a negative or positive statement as it is a biased statement. For the purpose of this scale, it was considered a negative statement. A l l statements were presented in random order to minimize the influence of statements on participant response. i i i . Discomfort To assess participants' discomfort related to milk and dairy products, 12 dairy-including items were used to assess discomfort. Respondents indicated whether or not specified food items caused discomfort upon consumption. Foods not causing discomfort were scored as minus one point, foods causing discomfort scored plus one point, and foods that were not consumed by individual participants were scored as zero points. Scores for each of the statements were summed to provide a total score for discomfort on a scale from -12 to + 12 points. A higher score therefore indicates more discomfort from dairy foods. 56 Chapter III: Methodology Data Analyses and Statistics A l l analyses were conducted with participants excluded on a case-by-case basis for missing data. Valid n is therefore presented for individual statistical analyses in the results section. The following section and Tables 3.2-3.8 present complete details of statistical analyses. i . Frequency and Percent Frequencies (count and percent) were calculated to describe the demographics of study participants, and responses to other categorical and continuous variables. Details are provided in table 3.2. i i . Descriptive Statistics Descriptive statistics were calculated to describe a variety of continuous variables. Details are provided in Table 3.3. i i i . Independent Samples T-Tests Independent samples t-tests were conducted to compare means of a variety of variables. F max was evaluated for homogeneity of variance and the appropriate t-test (equal variances assumed or not assumed) was selected. Table 3.4 presents details of t-tests calculated. iv. Analysis of Variance (One-way, Multivariate) And Post-Hoc Analyses Analysis of Variance (ANOVA) was calculated to assess for potential group differences in continuous variables (e.g., age, sex, vegetarian status, method of diagnosis). Post-hoc comparisons were conducted with Scheffe's test. Details of A N O V A conducted for this study are presented below in Table 3.5. 57 Chapter III: Methodology Table 3.2: Questionnaire items for which frequency statistics were generated. Demographics • Age, Sex • Ethnicity • Level of education • Vegetarian status Other items • Participant recruitment sources • Rate of return • Use of health care practitioners in diagnosis • Diagnostic tests used • Use of supplements • Symptom severity • Food avoidance by vegetarians • Knowledge scale items • Attitude scale items • Behaviour scale items • Ability to meet AI* or U L * * • Information sources • Information needs • Consumption of specific food items 58 Chapter III: Methodology *AI (Adequate Intake level); **UL (Tolerable Upper Limit) Table 3.3: Questionnaire items for which descriptive statistic were generated. Mean ± Standard Range Deviation Age of participants Mean symptom severity Mean calcium intake (food, supplementary or total) Mean knowledge (scale) Mean attitude (scale) Mean discomfort level (scale) Table 3.4: Comparisons for which t-tests were used to compare two means. Paired Samples • To determine i f calcium supplements significantly increase calcium intake Independent Samples To determine if: • calcium intake from incomplete food frequency questionnaires were different from complete food frequency questionnaires. • including milk significantly increases food calcium intake. • calcium intake was different among those including or excluding fortified non-milk beverage. • diagnosis by self or by a physician significantly increases calcium intake. • attitudes are significantly influenced by sex. 59 Chapter III: Methodology • attitudes are significantly influenced by vegetarian status. Table 3.5: Comparisons for which analysis of variance was used to compare three means. To determine if: • calcium intake (food, supplement or total) is significantly different by age, sex or age by sex. • calcium intake differs by vegetarian status (current, past or never vegetarian). • attitudes or knowledge are significantly different by age category or level of education. v. X 2 analyses Chi square analyses were calculated to assess for differences in categorical variables. Table 3.6 lists variables examined using chi square statistics. vi. Fisher's Exact Test Fisher's exact test is an alterative to the X2 test for testing the hypothesis that some proportion of interest differs between two groups. It has the advantage that it does not make any approximations, and so it is suitable for small sample sizes. Fisher's exact test was therefore calculated to replace or confirm the X2 in situations where the expected frequency in a cell is less than five, making the sample inappropriately small for a X2 to be of value. Details of tests where Fisher's exact was used are presented in Table 3.7. 60 Chapter III: Methodology Table 3.6: Comparisons for which X2 were calculated. To assess: • differences in proportion of each sex in each age group. • sex differences in proportion who met AI* using food, supplement or total calcium estimates. • differences in use of calcium supplements by method of diagnosis (self versus physician diagnosis). • sex differences in those reporting consuming calcium supplements. • differences in proportion of those consuming supplements by physician or self-diagnosis of lactose intolerance. • proportions of those including milk met their AI than those excluding milk. • frequency of symptom reporting differences among those reporting N A S * * or not reporting NAS. *AI = Adequate Intake level ** NAS = Non-associated symptoms Table 3.7: Comparisons for which Fisher's exact tests were calculated. • To confirm the X1 used to assess for difference in proportion of each sex in each age group • To confirm the X2 used to assess frequency of symptom reporting differences among those reporting N A S * or not reporting NAS *NAS - Non-associated symptoms 61 Chapter III: Methodology vii. Correlations Correlations were calculated to determine i f relationships existed between calcium intake and a variety of variables. Details are presented in Table 3.8. Table 3.8: Associations for which Pearson correlations were calculated. • Knowledge versus food calcium intake. • Attitude versus food calcium intake. • Discomfort and behaviour versus food calcium intake. 62 Chapter IV: Results Results Participants A total of 189 participants were recruited from all sources. In addition, six potential participants were excluded from participating during the recruitment phase: five chose not to participate due to the unavailability of compensation; one was excluded from participating for not meeting the inclusion criteria (the participant indicated having celiac disease). Sources of participant recruitment and number of participants recruited from each source are presented in Table 4.1. Participants recruited from advertisements placed in the Sun constituted the largest portion of study participants (68.3%). It is unknown how many participants were recruited from poster sources. Posters were in place at the same time as recruitment advertisements, therefore differentiating participants from poster and advertisement sourcing was not possible. A portion of participants from each source could be from poster recruitment. Table 4.1: Sources of participant recruitment. Source Approximate Number of Participants Recruited Percent Participants Recruited Link 1 0.5% Province 44 23.3% Sun 129 68.3% U B C Reports 5 2.6% Westender 10 5.3% Total 189 100% 63 Chapter IV: Results Of the 189 distributed questionnaires, 166 (87.8%) were returned. Seven questionnaires were excluded from analysis as they were not received within the set time limit. Data from 159 participants (84.1% of recruited participants) who returned completed surveys were analyzed. Of participants, 44 (27.7%) were male and 115 (72.3%) were female (Table 4.2). The age of participants ranged from 19-87 years, with a mean age of 47 ± 15 years. An independent t-test indicated that the mean ages for females and males, 47 ± 1 6 years and 46 ± 1 3 years respectively, were not significantly different, t( 100.6)= -6.52, p=0.52. Participants were categorized into age groups in accordance with Dietary Reference Intake (DRI) groupings. Table 4.2 illustrates the distribution of participants by age categories and gender. Three participants, all of whom were female, did not report their age. The distribution of participants in each age group did not differ significantly by gender: J^(3, N = 156) = 6.05, p < 0.11. Because one cell had an expected count less than five, the analysis was also conducted using Fisher's exact test (gender by age 19-50 versus age 50 and over). The absence of an association was confirmed with this analysis (Fisher's exact significance = 0.43). Table 4.2: Frequency and percent of subjects in different age categories by gender. Females Males Total Age Count Percent Count Percent Count Percent 19-30 23 20.5 4 9.1 27 17.3 31-50 42 37.5 25 56.8 67 42.9 51-70 37 33.0 13 29.5 50 32.1 >70 10 8.9 2 4.5 12 7.7 Total 112* 100 44 100 156 100 64 Chapter IV: Results T o t a l n=l 15 but three participants were excluded because they did not report age. Table 4.3 describes the ethnicity of participants. Just over half were of British or European ethnicity, and approximately one quarter listed ethnicity as "other". Frequency analysis indicated that 89 (56%) participants were Caucasian; 39 (24.5%) were non-Caucasian and the remainder were unable to be identified. Table 4.3: Ethnicity of study participants. Ethnicity Frequency Percent (%) British 43 27.0 European 39 24.5 British and European 12 7.5 Arab 1 0.6 Asian or Pacific Islands 15 9.4 Southeast Asian 10 6.3 Latin, Central or South American 2 1.3 Caribbean 1 0.6 North American Aboriginal 5 3.1 Other 31 19.5 Total 159 100.0 65 Chapter IV: Results Table 4.4 shows the distribution of the 43 participants listing their ethnicity as "other". A complete list of "other" ethnicities is provided in Appendix J. Seven participants listed themselves as Canadian or French Canadian. Considering the entire participant pool, it is likely that at least 107 (67.3%) participants were of Caucasian origin. Table 4.4: Distribution of self-described ethnicity. Ethnicity/Ethnicities Listed Other Ethnicity Listed Frequency Percent British or European North American Aboriginal, 6 3.8% + one other ethnicity Asian or Pacific Islands, Latin, Central or South American, and Caribbean British or European Aboriginal, Arabic, Belgian, Canadian, 8 5.0% + two other Chinese, Cuban, Dutch, French, French ethnicities Canadian Aboriginal, Irish American, Irish, Japanese, Jewish, Metis, Scottish, Sephardic, Welsh. Canadian 5 3.1% French Canadian 2 1.3% A l l other ethnicities Armenian, Chinese-Caribbean, Irish, Jewish, Ukranian, unknown mix including aboriginal. 10 6.3% 66 Chapter IV: Results Table 4.5 presents the educational background of participants. Over 80% of participants completed education beyond high school. Table 4.5: Educational background of participants. Frequency Percent (%) Secondary school or less 27 17.0 Trade/technical school or community college 49 30.8 Bachelor's/undergraduate degree 57 35.8 Master's or doctoral degree 26 16.4 Estimates of Calcium Intake Estimates of Calcium Intake from Food Sources Calcium intake was estimated using a food frequency questionnaire; table 4.6 presents data on estimated calcium intake. Intake data were compared to current daily Adequate Intake (AI) levels as defined by the 1997 DRIs: 1000 mg/day for males and females aged 19-50 and 1200 mg/day for males and females aged 51 and older. Complete data for the food frequency questionnaire were provided by 142 participants. Using an alpha of 0.05, an independent samples t-test indicated that participants with incomplete data (mean ± SD, 592 mg/day ± 371 mg/day, n=15) and participants with complete data (591 mg/day ± 380 mg/day, n=142) reported similar mean calcium intakes, t (155)= 0.02, p=1.0. Of the 142 participants who provided complete food frequency questionnaire data, three participants 67 Chapter IV: Results were excluded for not indicating their age. Mean calcium intake was therefore calculated for 139 participants. Eleven (11.2%) of 98 females and five (12.2%) of 41 males met the age specific Adequate Intake (AI) level for calcium from food sources alone. The proportion of males and females meeting their calcium AI from food sources alone were not significantly different: ^ ( 1 , 7V= 139) = 0.03,p< 0.87. When mean calcium intake from food sources was assessed using univariate A N O V A , there were no significant effects detected for sex (F = 0.46, p = 0.50) or age (F = 0.59, p = 0.62), nor was there an age-by-sex interaction (F = 0.51, p = 0.68). An independent samples t-test indicated that calcium intake from food sources did not differ between Caucasian and non-Caucasian participants, t(136)=0.38, p=0.71. 68 Chapter IV: Results Table 4.6: Mean calcium intake and proportion meeting calcium Adequate Intake (AI) using estimated calcium intake from food sources only and calcium fortified beverages. Age Group Gender Adequate Intake (mg/d) n Mean calcium intake ± SD (mg/d) % meeting AI (n) 19-30 m 1000 4 701 ±697 25% (1) f 1000 22 612 + 395 18.2% (4) 31-50 m 1000 23 619 ± 378 ' 17.4% (4) f 1000 39 614±436 17.9% (7) 51-70 m 1200 12 543 ±311 0 f 1200 32 545 ±317 0 70+ m 1200 2 272 ± 4 0 f 1200 5 652 ±348 0 Total m 41 588 ±386 12.2% (5) f* 98 593 ±383 11.2% (11) 139 591 ±382 11.5 (16) N o group differences were significant at p<0.05. *Data were not collected regarding pregnancy or lactation. 69 Chapter IV: Results Table 4.7 shows percentiles of calcium intake from food sources for the 139 participants who provided sufficient data. Values calculated for each percentile were similar between sexes. Table 4.7: Percentiles of calcium intake from food sources. Percentile of calcium intake Sex n 25 50 75 mg/day calcium intake Male 41 273 ' 513 794 Female 98 256 512 785 Total 139 269 513 784 •Values include calcium from calcium fortified beverages. Use of Calcium Fortified Beverages Calcium fortified beverages such as fortified orange juice or soy beverage were consumed by 77.6% (108) of participants. Mean daily intake of calcium provided from these beverages was 237 mg/day ± 231 mg/day with a range from 1 lmg/day to 1292 mg/day intake. Participants who consumed calcium fortified beverages (n=108) had an average calcium intake of 662 mg/day ± 390 mg/day compared to an average calcium intake of 416 mg/day ± 303 mg/day for those who did not include calcium fortified beverages. Calcium fortified beverages therefore provided 34.9% of calcium intake from food sources. An independent samples t-test indicated that participants who consumed calcium fortified beverages had significantly higher 70 Chapter IV: Results calcium intake from food sources than those who excluded calcium fortified beverages, t(137)= -3.59, p=<0.001. Estimates of Calcium Intake from Calcium Supplements One hundred and four (104) of 156 participants (67%) reported consuming calcium supplements. Twenty-six of 43 males (61%) and 78 of 113 (69%) females reported consuming calcium supplements of various forms. There was no significant difference between the proportion of males and females consuming supplements, ^=1.04, p=0.31. Complete calcium supplement data were provided by nine of 26 males (35%) and 52 of 78 females (67%). One female participant was excluded from the analysis for not providing age data, leaving a total of 60 participants who provided sufficient data. Table 4.8 shows daily calcium supplement intake for 60 participants, presented by gender and age group. Average daily calcium intake from supplements for all study participants was 746 mg/day ± 703 mg/day calcium. Females appeared to have higher mean calcium intake from supplements than males; however, assessment using univariate A N O V A revealed no significant effects for sex (F = 1.04, p = 0.31) or age (F = 0.45, p = 0.72), nor was there an age-by-sex interaction (F = 0.35, p = 0.70). Average supplement intake provided similar amounts of calcium as average estimated intake of calcium from food sources, t(50)=l .45, p=0.16. Of individuals consuming calcium supplements, 15% (16 of 64 who provided sufficient information) met their age appropriate AI based on supplement intake alone. 71 Chapter IV: Results Table 4.8: Daily calcium intake from supplements by gender and age group. Age Group Gender n Mean calcium intake ± SD (mg/d) 19-30 m 1 117 f 7 448 ± 400 31-50 m 5 370 + 292 f 17 927 + 896 51-70 m 3 700 ±397 f 20 780 ±579 70+ m 0 -f 7 884 ±988 Total m 9 452 ±351 f 51 798 ± 738 60 746 ±703 N o group differences were significant at p<0.05. Table 4.9 shows percentiles calculated for calcium intake from the 60 participants providing complete information on supplementary calcium sources. 72 Chapter IV: Results Table 4.9: Percentiles of calcium intake from supplementary sources. Percentile of calcium intake Sex n 25 50 75 mg/day calcium intake Male 9 167" ~~ 300 860~ Female 51 250 533 1200 Total 60 250 500 1000 Estimated Total Calcium Intake (Food and Supplementary Sources) Finally, estimated calcium intake from combined food and supplementary sources of calcium was calculated for participants who reported consuming calcium supplements. Eight of 60 participants were excluded for not providing complete information on the food frequency questionnaire. When combined with calcium intake estimates from the food frequency questionnaire, nine of 26 males (35%) and 43 of 78 females (55%) consuming calcium supplements provided sufficient data to estimate calcium intake from both food and supplementary sources. Data for total calcium intake (intake from food and supplementary sources) for 52 participants by sex and age, are shown in Table 4.10. Approximately 60% of participants met the acceptable intake level for calcium appropriate to their age and sex. Similar proportions of males and females met their calcium AI using a combination of food and supplementary sources (Fisher's exact test = 0.45). Analysis of variance was calculated to identify potential differences in calcium intake between age groups by gender. When mean calcium intake from combined 73 Chapter IV: Results food and supplementary sources was assessed using univariate A N O V A , there were no significant effects detected for sex (F = 0.01, p = 0.94) or age (F = 0.23, p = 0.88), nor was there an age-by-sex interaction (F = 0.70 , p = 0.50). Table 4.10: Participants meeting calcium AI using calcium intake from food and supplementary calcium sources. Age Group Gender n Mean calcium intake ± SD (mg/d) % meeting AI (n) 19-30 m 1 1848 • 100% (1) f 6 1236 ±527 50% (3) 31-50 m 5 972 ± 473 60% (3) f 17 1393 ±881 70.6% (12) 51-70 m 3 1222 ± 8 100% (3) f 17 1337 ±783 47.1% (8) 70+ m 0 - -f 3 1363 ±360 66.7% (2) Total m 9 1152 ±441 77.8% (7) f 43 1347 ±756 58.1% (25) 52 1313 ±711 61.5% (32) None o f the group differences were significant at p<0.05. 74 Chapter IV: Results A paired samples t-test was conducted to determine whether supplementation significantly increased calcium intake. The test indicated that total calcium intake was significantly higher than calcium from food sources alone, t(51)= -7.951, p<0.0001. However, a Fisher's exact test indicates that supplementation does not significantly increase the proportion of participants who met their AI (Fisher's exact = 0.08). Five participants had estimated calcium intake exceeding the tolerable upper limit (UL) established by the Dietary Reference Intakes. Intakes above the U L of 2500 mg calcium had a range of values from 2521 mg/day to 3448 mg/day, with supplements accounting for 1500 mg/day to 3200 mg/day calcium. Table 4.11 shows percentiles calculated for calcium intake from the 52 participants providing sufficient information on the food frequency questionnaire and the calcium supplement intake grid. Table 4.11: Percentiles of total calcium intake from food and supplementary sources combined, by gender. Percentile of calcium intake Sex n 25 50 75 mg/day calcium Male 9 838 Female 43 771 Total 52 , 790 1220 1161 1187 1397 1760 1728 75 Chapter IV: Results The Influence of Including or Excluding Milk on Calcium Intake Table 4.12 shows the calcium intake and ability to meet the Adequate Intake from food sources and from food and supplementary sources combined (total calcium) for participants who included or excluded milk. Participants were considered to exclude milk i f they excluded fluid milk only from their diet, that is, i f they did not consume milk in its fluid form. An independent samples t-test indicated that those who included milk consumed significantly more calcium from food sources, t(67.48) = 4.0, p<0.001. However, total calcium intake did not differ between participants who included or excluded milk, t(49) = 1.1, p = 0.28. Although participants who excluded all dairy products from their diet appeared to have lower intakes from food and the combination of food and supplements, these differences were not significant. Table 4.12: Calcium intake and ability to meet Adequate Intake by participants' inclusion or exclusion of milk products and dairy products from their diet. Valid Food calcium Meet AI Valid Total calcium Meet AI n (mg/d)±SD (food only) n (mg/d) ± SD (total calcium) Exclude milk 92 4 9 4 ± 3 1 5 a 5.4%c 41 1260 ±741 56.1% Include milk 45 7 8 4 ± 4 3 4 b 24.4%d 10 1537 ±598 80.0% a ' Values in the same column with different superscripts are significantly different at p<0.001 with a t-test. c d Values in the same column with different superscripts are significantly different at p<0.001 with aX2 test. A chi square analysis indicated that the proportion of participants meeting their Adequate Intake for calcium from food sources only was significantly greater for participants who included milk in their diet than for participants who excluded milk, X2 = 10.6, p = 0.001. The proportion 76 Chapter IV: Results of individuals including or excluding milk who met their A l using estimated total calcium intake values (food and supplements combined) was not statistically significant (Fisher's Exact = 0.28). Additional statistics were computed to assess whether exclusion of milk was higher in non-Caucasian populations. A chi square analysis indicated that proportions of Caucasian and non-Caucasian milk excluders were similar, X2 = 0.14, p = 0.71. Table 4.13 indicates mean calcium intake for participants by dietary inclusion or exclusion of cheese and yogurt. Food calcium intake was significantly greater for individuals who included cheese or yogurt than for those who did not. Therefore, cheese and yogurt contributed significantly to total calcium intake. Table 4.13: Mean calcium intake from food sources and ability to meet Adequate Intake by participants' inclusion or exclusion of cheese and yogurt from their diet. n Mean food calcium ± SD (mg/d) t df P Exclude cheese 30 411 ±290 -3.00 137 0.01 Include cheese 109 641 ±391 Exclude yogurt 67 452 ±320 -4.43 137 0.001 Include yogurt 72 722 ± 392 77 Chapter IV: Results Vegetarianism Participants were questioned about their vegetarian status. Of 155 participants who responded, 39 (25.2%) had followed a vegetarian diet at some past point in time and 12 (7.5%) were following a vegetarian diet at the time of the study. Three individuals did not answer whether or not they were following a vegetarian diet at the time of the study and were excluded from the analysis. Nine (38%) percent of past vegetarians and one (8.3%) current vegetarian avoided milk and dairy products. Past vegetarians reported avoiding "other" foods more than current vegetarians. "Other" foods included a variety of food items, such as non-organic fruits and vegetables, soy products, processed, sugary, starchy or "junk" foods. A full list of items avoided is included in Appendix K. Vegetarianism and Calcium Table 4.14 presents mean calcium intake for current, past and never vegetarians. An Analysis of Variance indicated that there were no significant differences among these groups (F= 1.3; p = 0.27). Table 4.14: Mean calcium intake from food sources for current, past and never vegetarians. n Mean calcium intake ± SD (mg/d) Current vegetarians 553 +253 Past vegetarians 23 476 ±286 Never vegetarians 101 618 ±413 None o f the group differences were significant at p<0.05. 78 Chapter IV: Results Table 4.15 presents mean calcium intake from supplementary sources of calcium, for current, past and never vegetarians. An A N O V A performed to assess whether calcium intake of current vegetarians differed from calcium intake from past vegetarians or never vegetarians showed a main effect (F = 3.34; p = 0.04) but there were no significant differences in pairwise comparisons. Table 4.15: Mean calcium intake from supplementary sources for current, past and never vegetarians. Valid n Mean calcium intake ± SD (mg/d) Current vegetarians 4 244+ 180 Past vegetarians 9 355 ±288 Never vegetarians 46 871 ±749 Total 59 750 ±708 A N O V A revealed a main effect (F=3.34; p = 0.04)_; however no pairwise comparisons were significant at p<0.05. Table 4.16 describes mean calcium intake from food and supplements combined, for current, past and never vegetarians. A one-way A N O V A performed to assess differences in calcium intake between never vegetarians, past vegetarians and current vegetarians indicated that these differences were significant (F = 4.59; p = 0.02). A Scheffe's post-hoc analysis (p<0.05) indicated that calcium intake of never vegetarians was significantly greater than calcium intake of past vegetarians. 79 Chapter IV: Results Table 4.16: Mean calcium intake from food and calcium supplements combined for current, past and never vegetarians. n Mean calcium intake ± SD (mg/d) Current vegetarians 4 825 ± 1 1 5 a b Past vegetarians 8 791 ± 5 6 7 a Never vegetarians 40 1 4 6 7 ± 7 0 6 b Total 52 1313 ±711 Values in the same column with different superscripts are significantly different at p<0.05 with A N O V A and Scheffe's post-hoc tests. Symptoms and Severity of Lactose Intolerance Table 4.17 demonstrates the frequency of symptoms experienced by study participants. Participants were asked to complete an open-ended question, recording the symptoms they associated with their lactose intolerance. Responses were categorized and presented below. Numbers reported are based on the number of participants who experienced a particular symptom. Symptoms reported by greater than 55% of participants were abdominal distention (bloating), diarrhea and gas/flatulence. Gastrointestinal noise was the least frequently mentioned symptom. Non-associated symptoms are symptoms reported by participants that are not established as diagnostic criteria or established as standard symptoms as reported in the literature. Non-associated symptoms reported included migraines, thickened mucous and insomnia. Other symptoms (those that could be perceived to accompany lactose intolerance, but 80 Chapter IV: Results are not true symptoms) reported by participants included vomiting and nausea (See Appendix L for complete list of non-associated symptoms and other symptoms reported by participants). Table 4.17: Frequency and percent of perceived symptoms of lactose intolerance reported by study participants. Symptom Frequency Percent Abdominal distension 86 55.1% Cramps 62 39.2% Diarrhea 100 64.1% Gas/flatulence 100 64.1% Gastrointestinal distress 60 38.5% Gastrointestinal noise 12 7.7% Non-associated symptoms 43 27.6% Other symptoms 25 16.0% Forty-three of 156 (27.6%) participants reported experiencing symptoms not typically associated with lactose intolerance (non-associated symptoms, NAS). Two of these 43 participants (4.7%) reported only non-associated symptoms. One additional participant reported non-associated symptoms and other symptoms only (data not shown). Table 4.18 shows symptoms reported by those experiencing and not experiencing non-associated symptoms. Chi square analyses indicated that participants who reported non-associated symptoms reported significantly less flatulence, more gastrointestinal distress, and more "other" symptoms compared to those not reporting non-associated symptoms. No significant differences were 81 Chapter IV: Results detected in the reporting of non-associated symptoms between participants who were self-diagnosed compared to those who were diagnosed by a health-care practitioner (Fisher's exact = 0.14). Table 4.18: Symptoms reported by those who did or did not experience non-associated symptoms (NAS). Symptoms reported % with NAS who reported other symptoms (n=43) Not reporting NAS (n=113) X1 Abdominal distention 48.8 57.5 0.95, p=0.33 Cramps 34.9 40.7 0.44, p=0.51 Diarrhea 53.5 68.1 2.91,p=0.09 Gas/flatulence 51.2 69.0 4.32, p=0.04 Gastrointestinal distress 51.2 33.6 4.05, p=0.04 Gastrointestinal noise 7.0 8.0 0.04, p=0.84 Other symptoms 25.6 12.4 4.03, p=0.05 Table 4.19 presents the severity of symptoms experienced by study participants. Sixty-nine percent of participants self-reported their symptomatic experience as somewhat severe or severe in nature. 82 Chapter IV: Results Table 4.19: Severity of symptoms experienced following the consumption of one cup of milk (any fat content) with a meal. Severity Frequency Percent Mild 7 4.6% Somewhat mild 8 5.2% Moderate 32 20.9% Somewhat severe 46 30.1% Severe 60 39.2% Total 153 100.0% Diagnosis Table 4.20 presents data on self-diagnosis versus professional diagnosis of lactose intolerance. Over half of the participants self-diagnosed lactose intolerance, and a family physician diagnosed another third of participants. 83 Chapter IV: Results Table 4.20: Self-diagnosis or the involvement of a health care practitioner in the diagnosis of lactose intolerance. Frequency Percent Self-diagnosis 85 53.8 Family Physician/Doctor 53 33.5 Other Physician/Specialist 14 8.9 Registered Dietitian/Nutritionist 2 1.3 Naturopath 3 1.9 Homeopath 1 .6 Total 158 100.0 , For the 73 participants who did not self-diagnose lactose intolerance, Table 4.21 presents data on tests used by all health care practitioners in the diagnosis of lactose intolerance. Seventy-eight percent of all practitioners used a description of symptoms as a diagnostic tool. Other tests were used by 30.1% of health care practitioners and included food and symptom diaries, vega testing, elimination diets, and elimination and challenge trials. A comprehensive list of other tests used is provided in Appendix M . 84 Chapter IV: Results Table 4.21: Diagnostic tools used by all health care practitioners in the diagnosis of lactose intolerance. Test used n Frequency Percent Hydrogen breath test 73 0 0 Description of symptoms 73 57 78.1 Fecal pH 72 5 6.9 Blood glucose/lactose tolerance test 72 7 " 9.7 Biopsy 73 3 4.1 Other tests 73 22 30.1 Results pertaining to the use of symptom description as a diagnostic measure should be interpreted with caution as reliability testing indicated that symptom description did not have an acceptable test-retest reliability, r = 0.48 (see Appendix H). The inability of the measure to meet the standards set for reliability (r > 0.75) indicates the potential for the item to provide inconsistent results, therefore limiting conclusions that could be drawn from the data. Table 4.22 presents diagnostic tools used by various health professionals. The hydrogen breath test (referred to as the gold standard for diagnosis) was not used. 85 Chapter IV: Results Table 4.22: Tests used by diagnosing health care practitioners. Diagnosing Health Hydrogen Symptom Fecal Blood Biopsy Other Care Practitioner Breath Test Description PH Glucose/Lactose Tolerance Test Test Family Physician 0 39 3 5 3 16 Other Physician/Specialist 0 12 2 2 0 4 Registered Dietitian/Nutritionist 0 2 0 0 0 1 Naturopath 0 3 0 ' 0 0 2 Homeopath 0 1 0 0 0 0 0/155 92/155 . 5/153 7/153 3/155 23/155 Table 4.23 presents a complete list of "other tests" used by physicians as part of diagnosis. Elimination diets were the most commonly used "other test". See appendix M for descriptions of tests used. In this study, the vega test was used exclusively by naturopathic practitioners (n=2). Among those with health care practitioners involved in diagnosis, the elimination diet was used by physicians (n=9) and dietitians (n=l). One participant self-diagnosed lactose intolerance based on an elimination diet. It was unclear in this specific case whether the elimination diet involved physician participation. 86 Chapter IV: Results Table 4.23: Other tests used in physician diagnosed lactose intolerance51 Test Used n % Allergy Test 1 5.9 Barium Study or Scope 2 11.8 Childhood Diagnosis 1 5.9 Elimination Diet 9 52.9 Vega 1 5.9 Other 3 17.6 *3 responses were not coded but are listed in appendix M Table 4.24 describes patterns of calcium intake among self versus physician diagnosed participants. Few participants were included in each group due to limited reporting of supplementary intake. No significant differences were found between groups for either supplemental or total calcium intake. Table 4.24: Food, supplemental and total calcium intake among self-diagnosed and physician-diagnosed participants. Diagnosis n Mean food n Mean supplemental n Mean total calcium ± SD calcium ± SD calcium ± SD (mg/d) (mg/d) (mg/d) Self 71 651 ±435 29 790 ± 764 24 1383 ±742 Physician 62 550 ± 308 27 696 ±670 25 1326 ±689 T-test results t(125.4) =1.56, t(47) =0.28, p=0.78 t(53.8) = 0.49, p=0.12 p=0.63 None of the group differences were significant at p<0.05. 87 Chapter IV: Results A chi square analysis indicated that similar proportions of self and physician diagnosed participants (50% and 47% respectively) consumed calcium supplements (X1 = 1.81, p = 0.18). An independent samples t-test indicated that there were no significant differences in food, supplementary or total calcium consumption between physician diagnosed and self-diagnosed participants. Knowledge Table 4.25 presents data from the lactose intolerance knowledge scale. The valid n is the number of participants who provided answers for a particular question. More than 80% of participants answered correctly for statements concerning the physiology and symptoms of lactose intolerance. More than 50% of participants were unsure of statements referring to false symptoms of lactose intolerance. On a scale from -12 to +12, the mean knowledge score of participants was 5.8 ± 2.4. Analysis of variance indicated that no significant differences existed in knowledge by vegetarian status (f=0.16, p=0.85), or age group (f=0.50, p=0.68). An independent samples t-test indicated that no significant differences existed in knowledge by sex (t(i n) = 0.87, p=0.38) or among self-diagnosed compared to professionally diagnosed study participants (t (i0i) =0.48, p=0.63). 88 c cu a CU m 0) 00 -a CU o cl cu CO c o CO cu c '£ cd CL, in CN T f cu 3 H cu 3 co cu co , 3 CU CU CU -4-» CS T f T f V O © ro I T ) o £ cd "cd £ to _g CU 1 - & "3 2 <u CL o o cd t3 * § -2, * -o o CO cd k> g is 3 a * t . cj O C - O ^ CD N CU -^T CU cd C? cd ^ E 6s-T f CN ro <n o G I - O - O =G td 3 E 0 *= S in rr, CU i—H -4—» H •£ 1 g c £ •is o CU Q, cd fa £ co in D CU -fj co cd 3 t: C d | o cu a =s cu o T3 co M cd cu t-i cd .cl -~ CU cu co Cl O >i <-> N J2 ci cu —r cu cd co cu C =5 cd o £ *  | •§ cF3 cd £ E V O vd © r-T f ro N ; O N © ' p ro VO ro CN m vd oo 0 0 </-) p oo CN ro IT) O I T ) T f ro CO T f cu -o * I-H >^  cd £ o Cl cd •— Ji 'o 0) CO O -»-< o cd o co E o CL 00 M cd O 2 CO CL I L -u CO cd O CO E o LH CL C 13 00 co <U o cd cd cu CN ro T f i n "-4—» a> -4—» CO c 3 O co W) _£ E cd cu t cd c 2^ cd 53 o o 0) co O O •J T f O N oo V O in cu CO O cu jd o c —^» co O s Id C 'cd a o CU H *2 'cd >-» cu cd >< cu CO CJ cs o LH CL cu o cu L -CU CO O -4-» CU cd T f CN O N ^ ^ oo oo VO 0 S - ^° \= oN \ ° p V O O in O O O N vq oo ON 0 0 in CN T f T f vd ro ON ro 0 0 0 0 0 0 O N ON O N CN O N '—i OO vo •—1 T f in o O L -CL 17 3 "cd CU cd Cl CU >> 13 cu "a, E o o o CO CU o Cl cd LH cu 3 -4—» _C cu CO O o cd cu 3, O cu CM Chapter IV: Results Attitudes Table 4.26 presents participants' agreement to attitude statements regarding milk and dairy products. Ninety-four percent of participants believe that milk and dairy products are good sources of calcium, while approximately two-thirds believe that they are natural foods and an important part of a healthy diet. More than 40% of participants hold negative opinions about milk and dairy products, as indicated by their response to the statements regarding the presence of hormones and antibiotics in milk and dairy products. On a scale of 1-40, the mean attitude score was 23.7 ± 4.9. An independent samples t-test indicated that no significant differences existed in attitudes among self-diagnosed compared to professionally diagnosed participants, t(n6) = 0.08, p = 0.94. Table 4.27 presents data on correlations between attitude statements and calcium intake from food sources. No statements were significantly correlated with calcium intake, nor was the total score on the "Attitude Scale" associated with calcium intake. 90 cu ^4 ca C o CO cu CO (3 O OH C O CU C cS '3 ca OH <4-H o fi CU CT1 CU CU cu ,6b ca s-. 4 — » CU cu C O 0 S - 0 S 6s- 6s- 6s- ox ox cn i n cn ON © CN VO © ON cn CN ON vo 00 i n 00 cn os ON 0 S 0 S - 0 S 0 S ' — 1 oo O > — ' ON CN CN os 0 S " 0 S CO cn 00 O ' — 1 CN © 0 S -oq cn 0 S o od CN os v « 0 S 6s-i n oq 00 cn CN ON m CN CO -t-» O o S-H OH 00 i n 00 m VO CN i n 00 i n m i n oo i n i n cd t3 fi ca 60 c 00 CU fi CU e CU -t—» ca - * — • CO CU T3 a VO CN •ST CU e cU s CU ca e CU CU CU CS I 3 'ca o C O CU o o co -a o o GO CU ca cu fi t3 O >-< OH -a C ca ca <H-H o •c ca O H u o OH C ca cu o fi O ca -w -73 ^ S i r rfi ca 2 X u O H PQ t3 C ca t3 O ,o ca "ca o (U ca o fi O OH 5 t3 fi ca T3 -*-» ca cu DO G '5 - O ca C O O O CO '-*-» O • T—( yO c o o o o c o T3 u -o o OH ca t3 C ca o c C O -4-» O B 3 ca o -a o c CU H—» CU co H - ' "73 ^ 2 co s Cd OH <u ^ C O V H 5 ^ t3 CU l a S -4—» C2 O o CU HO >^ ca a ca CO >> ca ca o ca CU a o co 3 CD CD H—' C3 CD 3 -O 3 cS co CD O UH O CO •3 O a a o CD M ca a _3 'o "3 o u. CO 3 _cS "CD t: o O C N CD •3 CD CD O c o C O O N O N i/-> C O V O C N C O C O C N C O O O N oo IT) C N o d d d d d d d d s CS 3 CD CD -4—• CS I £ _ C N V O in C O o o o O O o •—1 • 1 d d d d d d d d d cS o C4H o co CD CD UH 3 o co -3 o o 00 CD UH CS CO -4-» CD 3 -3 O OH X o m CD UH O H -4—| Is PQ CD CO CD xi cS CO 3 O o o tibiot £ part tibiot hor s co T3 3 CS CD *H-* cS O tain CD ort a tain ,3 OH "3 3 3 UH O CO PH 3 cS natu CD O 3 itain CD UH CD UH O c o cS cS T3 CD CO CO CO CO O O O O 3 3 3 3 * 0 •3 T 3 -o O o O O S-. UH UH UH OH OH OH OH CS cS cS cS cS -3 -3 -3 T3 T3 -3 -3 •3 T3 •3 3 3 3 3 3 cS cS cS cS cS M M -3 CD -4-< CS CD 00 3 '5 x> CD UH CS CO O u o 3 -3 O u. OH U ? 3 -3 UH O M 00 _s ' c o 3 -4—» 3 o -3 -4-* '% B .3 ' 5 "cS CD •a 3 O 3 CD -4—» CD 00 O cS CD CS & CD a o co .3 "3 CD -4—» cS 3 1 -4-> 3 o CD CD X> CS a CS , 3 H-J CO CS •3 cS £ O 3 •a -3 3 CD £ CD cS CD 00 CD T 3 5 « Z < CO o to 3 ~5 co cn u ""^  O o <-> O - » S j? S 3 B o co ti c S ° o 8 u ° p ° X O C 2 " * S w to h Jr- tU « O = 5 "O to C C co o u u 3 "a t: co CO S » s « « o CC C 1> CO CO 3C U O > o oa co CO U S u O u p J C tn o u ^ § .Si P " & c o 'P u o & CO - * O 3 B TD CO O CJ ^ u O. " >, M C c '•5 ° •31 2 s '5 u •a P fe ° O co 00 co c c 1 s H- =3 S = o o "5 ° •> u E — CO "5 x 1 o •£ g » 2 & g ca c c c c a> tu tu o £ £ £ £ a) 5 5 5 co cd cd co co m ty) U CO JJ CJ -C _c _c _c f— f— t— t— 92 Chapter IV: Results Age Comparisons Table 4.28 presents the attitude scores towards statements regarding milk and dairy products for participants in the 19-30, 31-50, 51-70 and 70+ groups. Mean attitude scores were similar between groups except for the statement regarding the presence of antibiotics in milk and dairy products, for which a Scheffe's post hoc analysis indicated that participants in the 19-30 year age group had higher mean scores than participants in the 31-50, but not the 51 -70 and 70+ group. An Analysis of Variance indicated that there were no significant differences in total attitude score among groups. Gender Comparisons Table 4.29 presents mean attitude scores and gender comparisons of attitudes using independent samples t-tests. Significant differences were found between males and females for three statements in the attitude scale, and the total attitude scale score. Independent samples t-tests were used to compare attitudes towards the statements presented regarding milk and dairy products by gender. The tests indicated that the overall attitudes of females towards milk and dairy products were more favourable than those of men. Males had significantly less favourable attitudes than females to the statement "Milk and dairy products are natural foods". Similarly, males exhibited less favourable attitudes than females to the statement "milk and dairy products do not contain antibiotics". Lastly, females exhibited significantly more positive attitudes than males to the statement "milk and dairy products are an important part of a healthy diet". 93 a, 3 o <u oo >, o o cj GO CJ T3 3 < do CN Tf ca H 3 co CJ LH < > o < Q -H CJ UH o o CO , u 3 ca CJ + o o o L O o ro c cj S CJ ta io CN o 0 0 ro o CO VO cn Tf o (N o O © o o o o o o o O oo ON vq CN CN ro —'< —'< o —< <N Os o +1 Tf Tf O O o +1 VO Tf' 6 .3 13 l a CJ CJ o UH 3 o CO '•8 o 00 CJ UH ca o ' 1 , ca " ° " O 3 ca oo o +1 ro Tf +1 0 0 ro ca Cw O -e ca a 3 ca •c o f c ca cj o 3 -a o a, ca H H -a CJ r3 ca as o +1 as cn +1 L O CN +1 oo ro +1 Tf CN +1 ro ro o +1 CN ro +1 C N Tf +1 ro ro +1 OS ro +1 O O ro CO O cS O "H ca 3 'ca CJ 3 o o 43 CJ 4= l a S ^ ca UH 3 -*—» ca 3 CJ UH ca CO •Un CJ 3 -a o UH ca • 3 •o 3 ca 4*i co c j O 3 O -a CJ 3 •3 O UH a ca -a 3 ca M 3 -4-* 3 O o o 3 •3 O O H - . 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G G cd § u* o cd CH-I O t ; cd O H c cd o O H 3 cd CD UH cd CO •4—* CD Tj O UH O H cd -4—> Tj .CD Tj TJ 4 3 r3 cd CD 43 CO -o O <£ "cd u. -4-» cd G CD CO H—» O Tj o UH O H 3 TJ TJ G cd 3 '3 -4—» 3 o o -4—4 o 3 o TJ CD TJ o UH O H u? 3 " O co cd O r§ rG H—• S cd CD 43 -4—» CO 0 '3 G o tS O TJ m w oo '3 pa TJ W , CO TJ CD S & cd o ^ § c/1 CD 3 O o 43 43 -4—" o 43 TJ CD HHJ cd CD UH -4-» COO 3 'S 43 CD UH cd CO O U 00 c 'co +-» O 43 -*-> • T-H a 'o "3 CD "S co 00 -4-> CD O t> & 00 <=> -B -*-» cd CO UH cd o co 32 TJ CD -4—» cd C 1 -4—• C o CD CD 43 cd cd 43 •4—* CO cd TJ cd O e •a 43 cd & CD a o co (3 oo Tf +1 CO Tf C N ON Tf +1 C N C N £3 CD a CD •4—* cd H—* CO "3 cd o oo CD TJ 3 95 Chapter IV: Results Vegetarianism Comparisons Independent samples t-tests were calculated to assess whether current and past vegetarians' attitudes differed. No significant differences were indicated (t(31)= -0.16, p= 0.88), therefore the attitudes of current and past vegetarians combined were compared to the attitudes of participants who were never vegetarians. Table 4.30 shows mean scores for attitude statement between current and past vegetarians, and never-vegetarians. Independent samples t-tests indicated that never vegetarians had significantly more positive attitudes on the total scale and on several individual statements. Education Comparisons Table 4.31 presents mean attitude scores by level of formal education. Analysis of variance statistics were used to assess whether attitudes towards milk and dairy products (individual statements and total scale) differed by level of education. A N O V A indicated that there were no significant differences between groups for the overall attitude scale (F^ H6 = 0.64; p = 0.59) or for any of the attitude statements. Scores for individuals reporting education beyond secondary school (including technical/community college, undergraduate degrees, and Master's/Doctoral degrees) were collapsed and compared to scores of individuals reporting education levels as high school less. An independent samples t-test indicated that no significant differences existed (t (143)= 1.2, p = 0.23). 96 3 -4—» CO a 2 'C 03 U OO cu > 43 3 CU a cu "ca cu 3 o o CO 3 ca cu o ro T f ' J U 3 ca H 3 co 3 CJ o, <u "3 3 3 O > X J X J 1 u. cd +1 cu o o CO 3 cd cu 3 cu a CU ta Cw XJ II fi 3 2 ca "cu cu > U. 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X) B 43 a •§ ^ o 5 H tO % 98 Chapter IV: Results Dairy Product Intake and Discomfort Table 4.32 shows the proportion of study participants who were able to consume a variety of food items containing dairy products without experiencing discomfort. Valid n is provided to identify the number of participants recording a response for each food item. Cheese based food such as pizza and lasagna, and unprocessed dairy products such as caffe lattes and milk, alone or in cereal, caused discomfort in more than half of participants. Dairy products that are typically consumed in small amounts (sour cream, creamer in tea/coffee) were consumed without causing discomfort by approximately one third of participants. There appeared to be little or no association between the.amount of lactose per serving of food and the proportion of respondents reporting discomfort. On a scale from -12 to +12, where positive numbers indicate more discomfort, average discomfort experienced from a variety of dairy products was 2.2 ± 5.6 (n= 132). Discomfort from consuming dairy foods was negatively correlated with calcium intake from food sources, as indicated by values from Pearson's correlation. The Pearson's correlation between calcium intake and discomfort experienced with the consumption of dairy foods was 0.35, p<0.05 (n = 132). This indicated that calcium intake therefore was lower in individuals with more discomfort from dairy foods, suggesting that people with discomfort avoided more dairy foods therefore potentially consuming less calcium in their diet from food sources. 99 c CD CJ U H CD <3 2 S o o -3 CD C/3 03 CJ O 3 U H o CJ OO 3 03 O oo a CJ • 3 O ,o >^ o 3 CJ T 3 3 CJ H CN r o Tf' JD 03 H CJ oo 3 U H CJ > CD 00 3 o 3 03 CJ O 3 00 CJ \& O CS 03 S o OH , PH a CD i o o C/3 •3 ,o o 0s 0s 0s 0s 0s 0s 6s- 0s 0s- 0s 0s Tf O N VO vq VO r o CN r-; oo r o O d CN Tf CN Tf ro — LO LO od d r o CN (N CN r o r o r o CN 0s- \ ° 0s 0s 0s 0s 0s 6s 6s 0s 0s- 0s 0s 00 r o ON r o CN r o ON p 00 VO LO HM l> CN VO r o od l—H ON r o od Tf vd LO LO LO Tf vo r o r o LO CN LO vo 0s 0s 0s 0s- ^5 0s 0s 6s 0s 0s 0s 0s oo oo LO CN r o O O N LO VO CN H-H Tf od CN LO ON LO vd r o r o r o r o Tf Tf CN Tf r o 2 °o >3 - U H - 3 O 2 3 O cj LO LO ro i-o O — i LO LO o LO ro LO Tf LO ro LO CN LO 0s ON LO CN LO O N O VO O VD O O — ; v d O CN r o . —< O Tf O r o vq d o vd o cn CJ o CJ o LO CN N o CN cS~ N N S) CD 03 uJ CJ CUH 03 u o r o 3 O O P H 40 03 03 <D 3 O 0 0 LO CN P H 3 o 4N a 03 CJ CJ 0 0 0 LO CD 3 3 O o 1 a o CD CJ CD ' P H CN 03 •3 • 3 CJ - 3 O x" CJ cD CD 4 3 O n CCJ X O r o cj CJ 4 3 o C S CD U H CJ X cj I CJ 00 CD <D 4 3 o O 0 0 o LO CN U H o N o 00 4 4 S-- 3 cj cS CD - 3 CJ O 3 - 3 CJ o CS o r o ti 00 43 03 CD ,CJ O a 3 5 a CS CJ U H o cj o 4 4 O 1*0 CN N O OO 4 4 100 Chapter IV: Results Information Sources Study participants were asked to identify which sources they used or have not used to gain information on lactose intolerance. Participants who have used specified sources are presented in Table 4.33. More than 80% of participants used popular media sources such as magazines and newspapers. Twenty percent used information from the dairy industry. In addition, 17 respondents indicated using other sources, including medical journals, trade shows, and other health providers such as pharmacists, osteopaths and acupuncturists. Complete data on other sources listed are available in Appendix N . Table 4.33: Frequency and percent of participants reporting information sources used to gather information on lactose intolerance. Information Source n Frequency Percent Magazines/Newspapers 149 120 81% Pamphlets 140 100 71% Television 123 60 49% Internet/Websites 125 54 43% Books (include textbooks) 141 93 66% Friends/Relatives 131 92 70% Physician 133 95 71% Naturopath/Homeopath 118 21 18% Dietitian/Nutritionist 121 37 31% Health Food Store 123 48 39% Dairy Industry 109 22 20% 101 Chapter IV: Results Participants were asked to indicate which source or sources were most helpful to them when learning about lactose intolerance, to which 145 participants responded. The open-ended question allowed participants to list an unlimited number of choices, and some participants provided multiple responses. Table 4.34 shows the number of individuals who listed each category as a first choice for which source provided the most useful information on lactose intolerance, and the total number of individuals who included the item in multiple responses. Table 4.34 Most useful information sources listed by participants. Frequency (%) as first choice Mentioned (total %) Magazine/newspaper 27(18.6%) 36(16.4%) Books 25(17.2%) 34(15.6%) Physician 17(11.7%) 29(13.2%) Pamphlets 15 (10.3%) 27 (12.3%) Internet 17(11.7%) 27 (12.3%) Friends/relatives 14 (9.7%) 19(8.7%) Other 12 (8.3%) 18(8.2%) Dietitian/nutritionist 6(4.1%) 11 (5.0%) Television 5 (3.4%) 7 (3.2%) Naturopath/homeopath 3(2.1%) 5 (2.3%) Health food store 2(1.4%) 4(1.8%) Dairy industry 2(1.4%) 2(1.0%) Total 145 (100%) 219(100%) 102 Chapter IV: Results Participants were asked to indicate which source or sources they would use if they wanted more information on lactose intolerance, to which 148 participants responded. The open-ended question allowed participants to list an unlimited number of choices and some participants provided multiple responses. Table 4.35 shows the number of individuals who listed each category as a first choice for what sources they would use to find more information, and the total number of individuals who included the item in multiple responses. The majority cited the internet as their primary resource for gathering more information on lactose intolerance. 103 Chapter IV: Results Table 4.35: Information sources participants would use for more information on lactose intolerance. Source Frequency as a first choice (%) Frequency of Mention (Total, %) Internet 67 (45.3%) 86 (34.8%) Physician 19 (12.8%) 40(16.2%) Other 20(13.5%) 35 (14.3%) Dietitian/nutritionist 11 (7.4%) 30(12.2%) Books 17(11.5%) 24 (9.7%) Pamphlets 2(1.4%) 8 (3.2%) N aturopath/homeopath 2(1.4%) 8 (3.2%) Magazine/newspaper 3 (2.0%) 7 (2.8%) Health food store 4 (2.7%) 5 (2.0%) Friends/relatives 1 (0.7%) 2 (0.8%) Television 1 (0.7%) 1 (0:4%) Dairy industry 1 (0.6%) 1 (0.4%) Total 148(100%) 247(100%) Information Needs Study participants were asked to identify whether or not they would like more information on five issues pertinent to lactose intolerance. Table 4.36 presents the number and percent of participants who reported wanting more information on lactose intolerance. Greater than 75%) of participants responding wanted more information on all of the topics. 104 Chapter IV: Results Table 4.36: Percent of participants wanting further information on lactose intolerance. Information Wanted n Frequency Percent wanting information What causes lactose intolerance? 136 106 78% How do I manage symptoms of lactose intolerance? 142 118 83% How do I find out how much milk or other dairy products I can have? 144 111 77% What foods can I eat in place of dairy? 147 125 85% Do I need a supplement? 139 107 77% 105 Chapter V : Discussion Discussion Introduction The purpose of this study was to assess calcium intake of individuals with self-reported lactose intolerance, and to examine diagnostic characteristics, knowledge, attitudes, and behaviours of these persons to determine potential relationships to calcium intake. This chapter discusses study results in relation to existing literature on calcium intake, attitudes and information sources. Participant recruitment, and demographics are discussed first to provide greater understanding of the study population. Estimated dietary and total calcium are discussed and compared to Adequate Intake (AI) values, followed by discussion of supplement practices. Next, diagnostic characteristics, implications of diagnosis and information gained from attitudes, knowledge and discomfort scales are discussed, separately and in relation to calcium intake. This is followed by a discussion of information sources. Finally, a discussion of limitations and recommendations for practice and future research are presented. Recruitment and Study Focus The majority of study participants were recruited from mainstream print media sources circulating in the lower mainland of British Columbia. More restrictively distributed media sources, such as ethnic newspapers, recruited an estimated 8.5% of participants. This may have contributed to the uneven distribution of participants' ethnicity. 106 Chapter V : Discussion Age and Ethnicity For participants, sex was evenly distributed among each age category, with a mean age of 47 years. Fewer participants responded in the upper most age groups, however generally speaking there were sufficient participants in each age group. The majority of study participants (-67%) indicated being of Caucasian or partly Caucasian heritage. This finding is of interest, as research reports indicate that individuals of northern European descent have high lactase levels, which remain high throughout adulthood, whereas individuals of non-northern European descent become lactase-non-persistent (Suarez et al., 1995). It is possible that individuals of northern European descent self-report lactose intolerance more than individuals of other heritages. This study cannot draw direct conclusions with regards to the incidence of self-reported lactose intolerance among persons with various ethnicities as the study used self-selection, not random selection. The increased prevalence of self-reported lactose intolerance may be due to voluntarism rates or self-selected participation among those of northern European heritage. There could be a variety of reasons why individuals of other ethnicities did not have higher rates of self-selection to participate in this study. Questionnaire Response Rate The overall and usable response rates (87.8% and 84.1% respectively), calculated from questionnaires returned versus questionnaires distributed, indicated that participants understood and completed the questionnaire with ease. There is a possibility that the non-respondents differed from the study population. While data were not formally collected on non-respondents, one potential respondent indicated withdrawal from the study in a personal letter. This non-107 Chapter V : Discussion respondent stated that the references to lactose intolerance in the questionnaire were different from her personal experience with lactose intolerance, and therefore she would not participate in the study for fear of biasing the results. This participant believed that arthritis and hip pain were due to lactose intolerance. It is possible that other non-respondents felt similarly, and would have provided an alternate set of opinions not found in the present study. This study focused on individuals with perceived lactose intolerance, and accordingly, recruited participants were required to self-report lactose intolerance. Participants therefore included individuals falling into the following categories: symptomatic lactose maldigesters (true lactose intolerance); symptomatic lactose digesters (experience symptoms of intolerance that are not due to maldigestion); and asymptomatic digesters (experience physical complaints not caused by lactose intolerance). Testing of study participants for lactose maldigestion and intolerance was not within the scope of the present study, therefore the results can only be generalized to individuals with self-reported lactose intolerance as individuals with true lactose intolerance comprised an unknown portion of the study population. Calcium Intake Estimated Calcium Intake and Calcium Intake in the Population Estimates of daily calcium intake from food sources in the present study (Table 4.5) indicated that male and female participants (age 19- 87 years) consumed 588 mg/day (± 386 mg/day) and 593 mg/day (± 383 mg/day) calcium, respectively. No significant effects were detected for age, sex or age by sex interaction. Daily calcium intake from food sources for all participants combined was 591 mg/day (± 382 mg/day). Data from the most recent National Health and Nutrition Examination Survey (NHANES III) collected in 1989-1990 indicated that 108 Chapter V: Discussion males and females (of all ages) consumed 976 mg/day (+ 1454 mg/day) and 744 mg/day (± 1038 mg/day) calcium respectively (Alaimo et al., 1994). Average daily calcium intake for both sexes in that study was 857 mg/day (± 1338 mg/day). Participants with self-reported lactose intolerance appear to consume less daily calcium from food sources than participants in the NHANES III study. However, the majority of study participants (66% or 92/139) completing the food frequency questionnaire herein did not consume milk, which may be the contributing factor to the lower average calcium intake from food sources among individuals with lactose intolerance compared to the general population. The proportion of participants excluding milk in the NHANES study is unknown. Furthermore, the lack of sex differences observed in the present study contradicts the information gathered in the NHANES III study. The comparison of the results herein to data from the NHANES III study presents some limitations. First, NHANES III data is based on the data from the U.S. population and may not directly indicate calcium intake among the Canadian population. The ethnicity of the NHANES III population differs from the present study; the U.S. population is comprised of a large proportion of Hispanic individuals. The ethnicity of the present study was largely Caucasian. As food intake and therefore nutrient intake can vary by ethnic population, comparison to U.S. data is not entirely applicable. Secondly, the NHANES III study collected data on calcium intake using a 24-hour recall procedure, a tool dissimilar to the food frequency questionnaire used herein to collect data. While the 24 hour recall method may show increased accuracy because it does not rely on long-term memory (Barrett-Connor, 1991), research has established that within-person variation is larger than between-person variation for most nutrients (Kushi, 1994). A 24 hour recall procedure has the potential to overestimate or underestimate nutrient intake. Alternately, food frequency questionnaires elicit information using a list-based 109 Chapter V : Discussion assessment and rely on long-term memory (Kohlmeier, 1994). This could inadequately prompt for food items not listed that may contribute to intake of a specific nutrient and result in reporting of fewer foods/nutrients than are truly consumed (Kohlmeier, 1994). The limitations of both the 24-hour recall and the food frequency questionnaire limit comparison between the NHANES III and data from the present study. There does exist a Canadian data set which may provide a valuable resource for comparison. In Gray-Donald and colleagues' study of Canadians (2000), calcium intake was estimated using a 24 hour recall. Mean calcium intake among males were estimated as 1375 mg/day (18-34 years), 1020 mg/day (35-49 years) and 901 mg/day (50-65 years). Calcium intake values for females were 875 mg/day (18-34 years), 764 mg/day (35-49 years) and 777 mg/day (50-65 years) (Gray-Donald et al., 2000). Among participants in the present study, mean estimated calcium intake from participants in each age and sex category of the present study appears lower than mean calcium intake among Canadians. Although the age groupings are not directly comparable between studies, they provide a reference for comparison. The lower calcium intake among individuals with lactose intolerance when compared to Canadian values confirms previously mentioned comparisons to U.S. data, suggesting that individuals with perceived lactose intolerance (which may include true lactose intolerance) have lower intake than the general population. 110 Chapter V : Discussion Adequate Intake Comparisons and Tolerable Upper Limits When studying calcium status, it is important to look beyond average values of estimated calcium intake. Due to the large range of estimated intake values herein, and the small population for whom estimated total calcium intake was available (n=52), it is important to identify the proportion of participants within each age -sex category that met the Adequate Intake level. It is also important to identify individuals with calcium intake levels above the tolerable upper intake level (UL) as established by the Dietary Reference Intake standards. The Adequate Intake (AI) value for calcium is 1000 mg for individuals (both males and females) aged 19-50, and 1200 mg for individuals (both males and females) aged 50 and over. The Tolerable Upper Limit (UL) is set at 2500 mg. Only 12.2% of male and 11.2% of female participants met the AI for calcium from food sources alone. Accordingly, the U L for calcium intake was not exceeded by food intake alone. When total calcium (food and supplementary calcium intake) estimates are considered, 61.5% of participants met their age appropriate AI for calcium. By sex, this was comprised of 77.8% males and 58.1% females. Although it appears that supplement use substantially increased the proportion of individuals meeting their AI, the difference in proportion meeting their AI from food sources and from total calcium sources was not statistically significant, although it approached significance (p = 0.08). The small sample size may have contributed to the lack of significant differences detected. Older Adults The average estimated calcium intake values for males and females age 51 -70 were 543 mg/day (n = 12) and 545 mg/day (n = 32) calcium, respectively, and intake values were 272 mg/day (n = 2) and 652 mg/day (n = 5) for males and females 70 years and older. The calcium 111 Chapter V : Discussion intake values of the 70 years and older cohort from the present study were unexpectedly lower than those values reported in the NHANES III study. However, it is difficult to truly compare estimated calcium intake of the 70 years and older cohort between the two studies due to the small number of participants in the present study. A Canadian study on the nutritional status of elderly people, classified as individuals over age 65, used a 7-day food record to estimate calcium intake (Payette & Gray-Donald, 1991a). The study found average calcium intake among male (n=35) and female (n=47) participants to be 687 ± 258 mg (691 mg median) and 622 ± 222 mg (565 mg median) (Payette & Gray-Donald, 1991a). Data from Payette and Gray-Donald's study are comparable to calcium data estimated from the present study. The authors reported that a 7-day food record provided enough information to accurately estimate calcium intake (Payette & Gray-Donald, 1991a). The number of participants and days of food records used fall within guidelines for accurate data collection provided by other authors (Basiotis, 1987) while the method used to estimate calcium intake in the present study potentially over or underestimates intake (Kohlmeier, 1994). Overall, 100% of older adults participating in this study had calcium intakes below the AI for their cohort. This is similar to a recent study on calcium intake of elderly women living in the Appalachia, where only 7% of participants exceeded 1000 mg calcium intake daily (Pfister, et al., 2001). However, Pfister and colleagues' comparison of intakes to a 1000 mg standard was not appropriate as the AI for the age group is 1200 mg. For individuals over age 50 years, the AI level for calcium increases from 1000 mg to 1200 mg daily. As the population ages, it becomes increasingly difficulty for individuals to meet their calcium needs as a result of higher nutrient recommendations and concomitant reduction in the volume of food intake. This combined with different food choices among the elderly has 112 Chapter V : Discussion been associated with reduced calcium intake (Drewnowski & Schultz, 2001). Therefore the inability of participants over age 50 years to meet their AI (based on food and fortified food intake only) was expected. The gap between average intake and the AI was greater for older adults, confirming that risk of inadequate intake is greater among the elderly compared to younger adults (Payette & Gray Donald, 1991a; Pfister et al., 2001). Dietary intake of calcium is therefore of concern among older adults, particularly those with self-reported lactose intolerance, as no study participants over the age of 50 met their age-appropriate calcium AI. Furthermore, inadequate vitamin D status in the elderly, resulting from various risk factors interacting in this population such as low milk intake (fortified with vitamin D) and impaired vitamin D synthesis (Matsuoka et al., 1991) may reduce the absorption of already limited dietary calcium. The results of the present study confirm other published reports suggesting that a large proportion of the elderly do not meet their calcium AI (Foote et al., 2000) and that most individuals would require calcium supplements or calcium fortified foods to meet the current AI for calcium (Nesheim, 1998). A study prepared by Foote and colleagues (2000) reported that substandard calcium intake was implicated in more than 80% of males and females over age 51. When diet and supplements were considered, the proportion of participants meeting their calcium AI rose by 6-7% for males and 20-23% for females for a total of 25% and 35% of males and females respectively meeting their AI. The authors suggested that supplement use reduced the percentage of individuals with low intakes by a small amount. Despite the high prevalence of supplement use, the population remained at critically high risk of inadequate intake (Foote et a l , 2000). In the present study, total calcium intake for participants over age 50 was 1325 mg when supplementary calcium intake was included. This value is approximately 30% above the AI, 113 Chapter V : Discussion indicating that supplementary calcium sources are important in helping individuals with self-reported lactose intolerance meet their AI for calcium. Supplementation increased the proportion of participants over age 50 meeting their age appropriate AI (food and supplementary calcium) by 62.5%. The improvement in the proportion of participants meeting the AI was expected, as supplementation significantly increases calcium intake, but the proportion increase was greater than that seen by Foote and colleagues. However, the proportional increase in calcium intake with supplement use was only assessed for participants who provided sufficient data on supplementation, rather than for all participants, as in Foote and colleague's study. For this reason, the findings between the present study and Foote and colleagues' are not directly comparable. The mean for the entire group of participants (i.e., supplement users and non-users) would have increased by a smaller amount than the increase observed in supplement users alone. Older adult participants in the present study had lower average calcium intakes from food sources than participants in the study by Foote and colleagues. Calcium supplementation in the present study appears higher than other reports of supplementation in the literature (Foote et al., 2000), and may therefore contribute to a greater proportion of older adults meeting their AI when consuming calcium supplements. It is possible that older adults with lactose intolerance are more concerned about their calcium intakes than older adults in the general population, thus stimulating use of calcium supplements with higher calcium values. Calcium Intake and Ethnicity An independent samples t-test indicated that calcium intake from food sources did not differ between Caucasian and non-Caucasian participants. This contradicts current literature, which suggests that milk is rarely consumed among Asian populations due to traditional low 114 Chapter V : Discussion milk consumption and cultural factors involved in infrequent milk consumption (Lau, Woo, Lam & Hong, 2001). However, this was expected given that similar proportion of Caucasian and non-Caucasian participants excluded milk. This is likely a result of lactose intolerance compared to cultural factors that limit milk consumption in the larger population of Asian individuals. Supplementation Practices Calcium supplements contributed significantly to calcium intake among study participants. However, the range of intake varied greatly from 10 mg - 3200 mg of calcium daily. The large range of calcium intake suggests the need for physicians, dietitians and other professionals involved in supplementation decisions to provide guidelines to individuals regarding the amount of calcium supplementation necessary to meet needs. Supplementation guidelines need to be clear and specific such that individuals will select a supplement appropriate to their needs. For example, calcium intake from food sources remained unchanged for the study participant who consumed 10 mg of calcium from a supplement. While the participant may or may not have thought that the supplement chosen was appropriate to help attain needs, the large range of calcium intake from supplements suggests that guidelines for intake are required. Among those consuming supplements in the present study, no significant differences in amount of calcium intake from supplements were observed between sexes. This finding counters the majority of supplementation literature that is currently available. According to Reid, Conrad and Hendricks (1996) women express more concern than men about specific nutrients such as calcium, and are more likely to consume calcium supplements. Additional literature suggests that this holds true among healthy elderly persons as well as the general population (Hartz et al., 1988). Recently, a Canadian study of patients attending family practice clinics confirmed that 115 Chapter V : Discussion females were significantly more likely than males to consume supplements (Durante, Whitmore, Jones, & Campbell, 2001). Population based research reporting patterns of supplement use among United States residents identified that in general, vitamin and mineral supplements were most used by adult females (Balluz, 2000). Individuals with more than 12 years of education, and those with middle or high incomes were more likely to use vitamin and mineral supplements (Balluz, 2000). Early supplementation literature indicated that more females report supplement use than males at each age decade (Hartz, et al., 1988). Currently, research literature confirms that females use supplements more than males (NIN, 1997; Durante et al., 2001), and that this trend also holds true among the healthy elderly (Hartz et al., 1988). Additionally, health beliefs may influence the decision to consume supplements. The absence of a sex difference in supplement use in the present study may relate to health beliefs and the widespread knowledge that dairy products are an important source of calcium. Health beliefs among participants in a Canadian study indicated that all participants believed calcium was preventative for osteoporosis (Durante et al., 2001). Similar findings were reported in a study on motivations for supplement use (Neuhouser, Patterson & Levy, 1999). Among North Americans, individuals indicated choosing to consume calcium supplements as a mechanism for preventing chronic disease (Neuhouser et al., 1999). Approximately one third of those consuming calcium supplements reported believing that the micronutrient could not be obtained at optimal levels from food sources alone. However, these studies were performed to be representative of the entire population, rather than representative of a population with a specific health concern such as lactose intolerance. Since the present study was performed specifically among individuals with self-reported lactose intolerance, there is a potential for greater equality between the sexes in choosing to consume supplements given that the majority of study 116 Chapter V : Discussion participants indicated an interest in learning about the need for calcium supplementation. It is likely that participants would be aware that, by excluding dairy products, their calcium intakes would be compromised. Furthermore, while osteoporosis has long been reported as a woman's disease, recent research indicates that it is of concern for males due to recognition that males have higher mortality following osteoporotic fracture than females (Johnell, 2001). Influence of Food Items on Calcium Intake Use of Calcium Fortified Beverages Calcium fortified beverages, such as fortified orange juice, have recently been made available for public consumption in Canada. This is the first Canadian study to identify the role of calcium fortified beverages on calcium intake from food sources. Analysis of consumption of such beverages indicated that they were consumed by 77.6% (108) of participants. The introduction of new fortified foods appears to have increased both the proportion of individuals who consume such products, and the amount of calcium in the diet provided by the same. A recently completed analysis of NHANES data from 1989-1991 indicated that at the time of the NHANES III study, only 5% of the population study consumed calcium fortified foods and fortification did not influence calcium intake (Berner et al., 2001). The lesser consumption of fortified foods may not be true today due to the wider availability of fortified products. Among those drinking calcium fortified beverages, mean intake of calcium provided from these beverages was 237 mg (± 231 mg) compared to 207 mg (± 185 mg) calcium consumed by participants who consumed milk as part of their diet. For study participants, calcium intake from fortified beverages provided similar amounts of calcium as milk. Calcium fortified beverages are fortified to have similar calcium concentrations as milk (Baker et al., 117 Chapter V : Discussion 1999). In this study, the consumption of fortified orange juice and other fortified drink products significantly contributed to calcium intake from food sources, indicating a positive role for fortified beverages in an individual's ability to meet calcium needs. Other Calcium Containing Foods Participant responses to questions in the discomfort scale indicated that products such as hard cheese, yogurt and lactose-reduced milk could be consumed to provide dietary calcium without causing discomfort. Approximately 45% of study participants indicated being able to consume these products without experiencing symptoms. Yogurt contains more lactose per serving than does hard cheese. Interestingly, yogurt was reported to cause discomfort in 32% of participants while hard cheese was reported to cause symptoms in ~40% of participants, suggesting that symptomatic experience is largely variable, without depending on quantity of lactose consumed. While not directly comparable, this finding mimics those by Vesa and colleagues (1996) where random consumption of test milks containing 0-7 g of lactose consumed produced inconsistent symptoms in 60% of maldigesters. No direct conclusions can be drawn, as the present study did not control the setting in which foods were consumed or symptoms reported. Furthermore, while 45.3% and 49% of participants tolerated yogurt and hard cheese respectively, cheese based food such as pizza and lasagna, caused discomfort in 50-60% of participants, similar to unprocessed dairy products such as caffe lattes and milk (alone or in cereal). This further supports the lack of relationship between symptoms experienced and quantity of lactose consumed. It is difficult to quantify this exactly as recipes differ between households, restaurants and retail food producers, but the quantity of cheese in pizza and lasagna 118 Chapter V : Discussion is likely similar to the quantity consumed as a separate portion. Alternately, the larger proportion of individuals experiencing symptoms from mixed foods may suggest that substances other than lactose in food may contribute to symptoms experienced. The smaller proportion of participants that experience discomfort after consuming yogurt, hard cheese and lactose-reduced milk suggests that these products may be used by some individuals to enhance the ability to meet one's AI. This may significantly improve the calcium intake of some individuals, given the significant contribution of milk, cheese and yogurt to food calcium intake observed in this study. Considering an individual person's overall health, yogurt and hard cheese (regular or reduced fat) may be recommended in an attempt to help individuals improve the adequacy of their calcium intake. It would seem, given the ability of dairy products to significantly increase calcium intake from food sources, that simple dietary advice could boost calcium intake. However, given the negative attitudes about milk in some groups/individuals found in this study, and other studies (Pfister et al., 2001), advice on using food calcium sources (specifically milk) would be of limited use in helping individuals attain their AI. Compliance among those intolerant of milk or disliking milk would be an issue (Pfister et al., 2001). Furthermore, the United States government recently developed the Healthy People 2010 to reflect necessary changes resulting from the final assessment of the Healthy People 2000 statement. In Healthy People 2000, the goal was to increase the proportion of the population consuming three servings of calcium rich foods daily, with a focus on dairy products (Healthy People 2000, U.S. Department for Health and Human Services, 2001). Research indicated that the proportion of the population meeting this goal moved away from target. Only 21% of individuals over age 25 consumed the recommended two or more daily servings of high calcium foods (Office of Disease Prevention 119 Chapter V : Discussion and Health Promotion, U.S. Department for Health and Human Services, 2001). As a result, Healthy People 2010 changed to avoid focusing on dairy and to include a focus on the use of fortified foods and supplements to meet calcium needs (Office of Disease Prevention and Health promotion, U.S. Department of Health and Human Services, 2000). Calcium Intake and Vegetarianism Past research has speculated that the nutrient value of vegetarian diets may be different from non-vegetarian diets. In the 1990s, it was established that people consuming vegetarian diets adhere to nutrient recommendations more than do non-vegetarians (Health & Welfare Canada, 1990), stimulating queries as to whether vegetarians differ from non-vegetarians in their ability to meet nutrient recommendations. Recent research has indicated that intakes of most but not all nutrients were similar between people consuming vegetarian and non-vegetarians diets, with no significant differences found in calcium intake (Barr & Broughton, 2000). In the present study, estimated calcium intake were similar between current, past and never-vegetarians, supporting findings by Barr and Broughton (2000). A one-way A N O V A performed on supplementary calcium intake of current, past and never vegetarians indicated a significant difference between the supplementary calcium intake of the three groups, but the direction of difference could not be specified. Estimates of total calcium intake (food and supplementary sources combined) indicated that never vegetarians (n = 40) had significantly higher calcium intakes than past vegetarians (n = 8) but not current vegetarians (n = 4). The small number of participants classified as current and past vegetarians increase the difficulty of making meaningful comparisons to the larger population of individuals 120 Chapter V : Discussion with self-reported lactose intolerance who are or have been vegetarian. Future research may be indicated in this area. Diagnosis The American Gastroenterological Association guidelines for the diagnosis of lactose intolerance advocate the use of a diet history with judicious use of other testing methodology (American Gastroenterological Association, 1999). Medical reference texts similarly recommend diagnosis based on the effects of milk ingestion alone or following an elimination diet (Jacobs et al., 1996). However, diagnostic reference sources available to physicians do not discuss or emphasize the prevalence of misdiagnosis using these techniques. The majority of participants in this study indicated self-diagnosis of lactose intolerance. However, physicians were involved in -43% of diagnosis (n=67), and in some cases were used to confirm self-diagnosis. Analyses performed on the frequency of tools used for the diagnosis of lactose intolerance indicate that valid diagnostic tools (breath hydrogen and lactose tolerance test) were used infrequently. Breath hydrogen testing was not used in the diagnosis of any study participants. Among the 73 participants with health professionals involved in diagnosis, the lactose tolerance test was used in the diagnosis of ~10% of participants (n=7). Seventy-eight percent of participants with health professionals involved in diagnosing lactose intolerance had symptom description used as a diagnostic tool, despite the indication that symptom description alone is inappropriate in the diagnosis of true lactose intolerance, or symptomatic lactose maldigestion (Villako & Maroos, 1994). Elimination diets accounted for an additional 41% (9 of 22) of "other" tests used in diagnosis. These data indicate that physicians' diagnoses follow guidelines and medical reference literature that advocate limiting the use of valid diagnostic tools 121 Chapter V : Discussion in clinical practice, instead diagnosing lactose intolerance following symptom description or reporting of diminished symptoms following a lactose-free diet (Jacobs et al., 1996). Following the research literature guidelines for diagnosing lactose intolerance, individuals would be tested using valid diagnostic tools before a definitive diagnosis of lactose intolerance would be made. In this study, the majority of physician diagnosed lactose intolerance would not be considered confirmed diagnoses of lactose intolerance. Therefore, the diagnosis would provide little more than a name for patients to give their gastrointestinal discomfort or complaints. The patient may or may not benefit from this diagnosis. If lactose intolerance was perceived by an individual, the diagnosis of intolerance and reduced stress response that may accompany a tangible diagnosis may be enough to alleviate perceived symptoms, with or without the avoidance of milk or dairy products. Furthermore, a potentially improper diagnosis of lactose intolerance perpetuates "dairy myths" in popular media sources -the common ideology that dairy products are poorly tolerated and constitute a dietary anomaly. Contraindications to the Use of Valid Diagnostic Tools Cost analysis is a relevant consideration in the use of valid diagnostic tools to evaluate lactose maldigestion and intolerance. In British Columbia, there is a $15 cost to patients for undergoing a glucose tolerance test, used for the diagnosis of lactose maldigestion (lactose tolerance test) as well as diabetes and intermediate glucose tolerance (Personal communication, MDS Metro Labs, 2001). [Breath hydrogen testing is unavailable]. However, the total cost to the medical services plan (MSP) of the province is likely considerably greater, as lab time, reagents, lactose solution and staff salary required for the test have not been accounted for due to the logistics of the MSP system (Personal communication, MDS Metro Labs, 2001). 122 Chapter V : Discussion The cost of $15 per patient seems reasonable for an accurate diagnosis of lactose maldigestion. However, where increasingly precise fiscal management of medical services is in place to provide better health care for fewer available dollars, it is the unseen costs that may prohibit the use of this diagnostic tool. Symptoms and Diagnosis A comparison of reported symptoms indicated that 22% and 32% of self-diagnosed and physician diagnosed participants (respectively) reported experiencing non-associated symptoms (NAS; symptoms not typically associated with lactose intolerance, e.g., insomnia). No significant differences were found in reporting of NAS between groups. The lack of significant difference suggests that the role of physician in diagnosis of lactose intolerance by symptoms description requires reassessment, as the diagnosis of lactose intolerance based on symptoms which include NAS, may increase the prevalence of misdiagnosis. Furthermore, physicians' role in patient education of lactose intolerance also requires reassessment. Physicians should be encouraged to carefully assess symptoms and educate patients regarding which symptoms are related to lactose maldigestion, in a non-judgmental manner. Additionally, participants reporting NAS also reported more gastrointestinal distress and "other" symptoms than those who did not. Past research has indicated that symptoms of other gastrointestinal dysfunctions resemble those of lactose intolerance (Shaw & Davies, 1999; Vesa, Marteau, & Korpela, 2000). Visceral sensitivity is greater among those with irritable bowel syndrome, and these individuals have lower perception and discomfort thresholds for gastrointestinal distention (Vesa et al., 2000). Findings herein support this, and suggest that participants reporting NAS were likely to experience other gastrointestinal dysfunctions rather 123 Chapter V : Discussion than lactose intolerance, reaffirming the need to encourage health care practitioners to carefully monitor and assess symptoms reported by patients as lactose intolerance. Implications of Diagnosis As previously mentioned, the diagnosis of lactose intolerance based on symptom description and elimination diets is contraindicated in research literature, as it may lead to misdiagnosis. Thirty-one percent of individuals (Finnish descent) who were diagnosed as lactose intolerant based on symptom description were found to be lactose digesters when tested with clinically relevant tests (Villako & Maroos, 1994). And, of the remainder who maldigest lactose, few were "intolerant" when tested under double-blind conditions (Vesa et al., 1996). The large proportion of physicians who diagnose individuals with lactose intolerance based on symptoms has potentially detrimental nutritional implications for individuals with gastrointestinal complaints, because milk avoidance is commonly advocated. Milk avoidance is not unique to North America; researchers in Finland have indicated that among individuals where diagnosis of lactose intolerance was unclear, 62% of physicians advised their patients to avoid milk (Peuhkuri, Vapaatalo & Korpela, 2000). Calcium intake is noted to be lower for individuals avoiding milk than for individuals in the general population (Heaney, Dowell, Rafferty & Bierman, 2000). Similarly, an independent samples t-test comparing participants who included and those who excluded milk in this study, indicated that participants who included milk in their diet consumed significantly more calcium from food sources. Avoidance of milk and dairy products is unnecessary in those without true lactose intolerance, therefore the misdiagnosis of lactose intolerance may lead to an increasing number of individuals unnecessarily reducing calcium intake via the avoidance of dairy products. 124 Chapter V : Discussion Given the potential reduction in dietary calcium intake and the limited ability of individuals to meet their calcium needs from food intake alone (~11%), physicians should be encouraged to discuss calcium rich food sources or recommend calcium supplementation to their patients diagnosed with lactose intolerance. In the present study, a chi square analysis indicated that similar proportions of self and physician diagnosed participants consumed calcium supplements. Furthermore, calcium intake from supplementary sources was similar between these two groups. This was contrary to the expectation that a larger proportion of individuals with physician diagnosed lactose intolerance would consume calcium supplements and have higher supplementary intake than self-diagnosed individuals. These data suggest three possibilities: first, that physicians do not currently advocate calcium supplements to their patients; second, that patient compliance with physician recommendations for supplementation may be limited; third, that self-diagnosed individuals are more likely to consume calcium supplements due to internal motivation or social support. The lack of significant difference in calcium supplementation between physician diagnosed and self-diagnosed participants is congruent with lack of physician recommendation for supplementation or poor compliance with supplementation, and therefore cannot be discounted. Patient compliance is a consideration in recommending supplements to enhance a person's ability to meet calcium needs (Baker et al., 1999). Understanding of available supplements may also be a consideration. There are a variety of supplements available for purchase by the public. The high bioavailability of calcium carbonate and calcium citrate malate compared to calcium gluconate encourage recommendations of these forms of supplements (Miller, Jarvis & McBean, 2001). The ability of calcium citrate malate to be absorbed regardless of stomach acidity, and the general belief that it is more highly bioavailable than other calcium 125 Chapter V: Discussion supplements despite research to indicate otherwise (Heaney, Dowell & Barger-Lux, 1999), may encourage physicians to recommend this supplement. However, this form may be less likely to be used as it often commands higher retail prices than more commonly available forms such as calcium carbonate, and individuals consuming supplements may halt supplementation when supplements are considered too costly for the lack of immediate benefit. In the elderly population, chronic illness may require long-term management with several medications. Due to the limited financial resources available to some individuals, nutrition may not be a priority as evidenced by the prevalence of malnutrition in the elderly (Torres-Gil, 1996). Supplements may be reduced or removed to preserve the ability to maintain prescription drug use. Additionally, research assessing vitamin and mineral supplement use indicated that respondent confusion exists regarding micronutrient composition of supplements (Patterson, Kristal, Levy, McLerran & White, 1998). Participants made inaccurate assumptions about micronutrient composition of multivitamins and exhibited confusion over the distinction between multivitamins and single supplement use, suggesting that participant consuming supplements for specific reasons (i.e., to obtain calcium) may not be achieving that goal. Supplementary calcium intake of individuals with self-reported lactose intolerance in the present study ranged from 10 mg to 3200 mg per day. This large range suggests that confusion may play a role in supplementation by study participants; it is plausible that participants do not know which supplements provide appropriate amounts of calcium. The relevance for clinical practice lies in ensuring that individuals needing calcium supplements understand the type of supplement and amount needed to maintain or improve health as related to calcium intake. 126 Chapter V : Discussion Attitude The results of the present study support prior research suggesting that adults with lactose intolerance or other health concerns related to milk, held more negative opinions of milk and were more likely to limit milk consumption when compared to the national average (Commins & Wingrove, 2000). Of participants herein, approximately 80% agreed that cows are being treated with hormones, compared to 31 % BC residents and 24% of Canadians nationally (Commins & Wingrove). Additionally, 54% of study participants agreed that milk and dairy products contain antibiotics, compared to 59% of BC residents and 46% of Canadians nationally (Commins & Wingrove, 2000). Rates of misperception (as indicated by response to attitude statements) among individuals with lactose intolerance appear more prevalent than in the general population with regards to treatment of cows with hormones, but appear similar to the general population with regards to the presence of antibiotics in milk. Results of the present study warrant comparison to a recent Vancouver study of current, past and never vegetarian women (Barr & Chapman, 2002). The authors reported that 50% and 46% of vegetarian and past vegetarian women believed that dairy products contain antibiotics; 19% of non-vegetarian women in the study held the same belief (Barr & Chapman, 2002). As previously mentioned, 54% of participants in the present study agreed that dairy products contain antibiotics. Additionally, 40% of study participants agreed with the statement "milk and dairy products contain synthetic hormones (rBST or rBGH)", similar to the 48% and 51% of current and past vegetarian women in Vancouver who indicated a belief that dairy products contain unnatural hormones (Barr & Chapman, 2002); only 26% of non-vegetarian women held the same belief. The comparable beliefs suggest that study participants have comparable beliefs regarding these statements to current and past vegetarian Vancouver women. 127 Chapter V : Discussion Surprisingly, attitudes did not differ significantly by level of education. However, participants in the 19-30 age cohort had significantly more positive attitudes towards the statement "milk and dairy products do not contain antibiotics" than participants in the 30-50 age cohort. This was unexpected as many marketing campaigns that focus on the negative aspects of dairy products seem to target younger age groups. The mean attitude score toward the statement was neutral, suggesting that participants may be balancing both the positive and negative media regarding dairy products. Fifty-two percent of study participants agreed with the statement "I think nowadays that milk may be contaminated in some way". According to the study that originally looked at participant responses to this statement, 27% of participants across-Canada and 43% of British Columbians agreed with this statement (Commins & Wingrove, 2000). The greater agreement with these statements corroborates the idea that negative attitudes are more widespread among those with lactose intolerance than among the general population in Canada. However, the proportion in agreement with the statement does not appear much greater than those in British Columbia, suggesting that attitudinal differences may be due to both location of the study and the underlying condition of lactose intolerance. Attitude by Vegetarian Status Individuals may choose to become vegetarian for a variety of reasons, including religious beliefs, philosophical and ethical beliefs, personal health, environmental and ecological concerns, and economic status (Krey, 1982; Rajaram & Sabate, 2000). While health is the most commonly reported reason for practising vegetarianism (Dwyer, 1994), anecdotal reports suggest animal ethics may strongly promote one's decision to become vegetarian. For individuals citing 128 Chapter V : Discussion animal ethics in their choice of becoming vegetarian, it seems congruent that individuals would be more likely to believe that animals are treated poorly. This may extend to purported use of synthetic hormones in food animals, given widespread media attention to such issues. As expected, vegetarians had significantly more negative attitudes on the total attitude scale than non-vegetarians. Vegetarians were less likely to consider milk and dairy products as natural foods or important parts of a healthy diet, and exhibited more positive attitudes towards attaining calcium without using milk or dairy products. Further, vegetarians exhibited stronger agreement to statements regarding the use of synthetic hormones to treat cows and the presence of such hormones in milk and dairy products. Information Sources Magazines and newspapers were cited by 81 % of study participants as sources of information on lactose intolerance, establishing them as the most widely used information source. Articles in popular media sources can help consumers adopt healthy eating practices, or can be counterproductive to health behaviours (Woznicki, & Kava, 1996; Kava, 1997). More than 75% of sources reviewed by Woznicki and Kava (1996) provided excellent or good sources of information while only 23% provided fair or poor information. In the present study, information on specific titles of popular media sources were not collected, therefore it is not possible to determine the accuracy of information gathered among study participants. However, the wide variety of available popular media sources indicate that information received can range from poor to excellent information. Similar proportions (-70%) of individuals utilized friends and relatives, physicians, dietitians and pamphlets as previous sources of information on lactose intolerance. Internet and 129 Chapter V : Discussion physician sources were comparable in terms of how useful they were rated by study participants, while usefulness of information from friends/relatives and dietitians lagged slightly behind. Thirty-four percent and 29% of participants rated the internet and physicians as their most useful sources (respectively), in comparison to 86% and 40% indicating the internet and physicians as a future source of information. A larger percent of the study population cited the internet as a source of future information, likely due to its wide availability. This suggests that focusing on physicians as the sole information source for lactose intolerance and calcium intake (food and supplements) would be limiting to information availability, countering literature-established suggestions that physicians are key channels of information to consumers (NIN, 1997). While physicians are considered to be a helpful source of information, focusing on physicians as an information source instead of including electronic media, may limit the number of people that would be reached with accurate information. The results of the present study indicate increasing reliance on the Internet (websites) be it for past, present or future information. These results not only confirm reports that the internet is used for dissemination of medical and health information (Groot, Riet, Khan & Misso, 2001), but confirms decreasing reliance on "trusted" information sources (such as physicians) in response to electronic media (Reid et a l , 1996). While the internet is an easily accessible information medium for many individuals, the accuracy and quality of available information is questionable (Groot et al., 2001; Jmpicciatore, Casella & Bonati, 1997). Internet sites providing health information are not subjected to peer review for quality and validity of information (Bar-on, 2001). Research has not specifically been conducted to focus on the accuracy or reliability of information regarding lactose intolerance on the internet. However, due to lack of control, 130 Chapter V : Discussion assessment and assurance of information quality (Impicciatore et al., 1997), evaluations of health information (including dietary information) available on the internet have been performed. Few websites provide complete and accurate medical information (Impicciatore et al., 1997). Studies on available healthcare and medical information on the internet suggest an urgent need for greater monitoring of internet sites for accuracy, completeness and consistency of information (Impicciatore et al., 1997). Like any other internet site, the dietary information provided and the quality of that information is established by the publishers, whether they are health organizations, retailers or individual internet sites (Davison, 1997). The uncertain quality of nutrition information is documented (McCarthy, 2000). An assessment of 365 documents relating to food and nutrition indicated that 45% of documents were inconsistent with Canadian eating standards (Davison, 1997), confirming anecdotal reports of the widespread prevalence of misinformation on the internet. The great proportion of individuals with self-reported lactose intolerance using the internet as an information resource, combined with the increasing availability of internet resources reinforces the need for health professionals to actively play a role in addressing inconsistent and inaccurate dietary information on the internet. Health professionals will play an important role in identifying internet sites with accurate information on lactose intolerance and relevant dietary guidelines. The role of health promotion will also become more important (ie., promoting awareness and use of web-based tools such as Tufts Nutrition Navigators, which was designed to help effectively search through nutrition websites for accurate and useful information). 131 Chapter V : Discussion Information Needs More than 77% of study participants reported wanting information on lactose intolerance, symptom management, and need for calcium supplementation. Similar proportions wanted information on how much milk or other dairy products could be consumed on an individual basis, and foods that could be used to replace dairy products. However, some of the information ascertained by this study was overlapping and suggest that participants were interested in meeting calcium needs using a variety of sources. Seventy-seven percent of participants wanted information on finding out how much dairy products they could include in their diet, while 85% wanted more information on foods that could be eaten in place of dairy products. Overall, the large proportion of participants who indicated wanting information suggests that study participants are open to further education about lactose intolerance. Education materials should be developed specifically to address some of the information needs identified in this study. For example, the Calcium Calculator ™ could be adjusted to indicate where supplements could be used in combination with food intake to reduce potential deficiencies in calcium intake. Currently, the Calcium Calculator ™ is available as an interactive tool (web-based or on CD-Rom). Future efforts to develop education materials could aim at programming the Calcium Calculator ™ to identify specific areas where individuals could add foods to improve calcium intake. For example, i f one category of calcium containing foods is consumed in low amounts, the Calcium Calculator ™ tool could be programmed to identify that area to a user and suggest ways to add such foods into their diet. See Figure 5.1 for details. 132 Chapter V : Discussion Figure 5.1: Details of potential modifications to Calcium Calculator ™ tool. Person A uses the Calcium Calculator ™ to assess calcium intake. i Person A does not include any sources of calcium from green vegetables such as bok choy or broccoli. Legume based sources were not indicated by Person A as a food item consumed. I Calcium Calculator ™ analyzes calcium intake and sources of food calcium used by Person A. Leafy greens and legume sources of calcium are identified as under-represented in Person A 's diet. i Calcium Calculator ™ personalizes final messages to Person A and suggests consuming leafy greens and legumes. Person A follows through adult education materials in the final steps of Calcium Calculator ™ and can identify amount of calcium provided by these sources. I Recipe ideas are also available for viewing. (I.e., High Calcium Japanese Sesame Tahini Salad Dressing; Quick Chickpea Lunchtime Sandwich Wrap). 133 Chapter V : Discussion Limitations Study Design The present study was a survey design where participants with self-reported lactose intolerance completed and returned a questionnaire. This study design imposes a potential limitation because a control group was not selected to provide reference data against which data from participants with self-reported lactose intolerance could be compared. This may be of particular importance to the issue of estimated calcium intake, as it is not possible to determine whether calcium intake of those with self-reported lactose intolerance is higher, lower or the same as those in the general population. Data are available on calcium intake in the population, however this data is American and may not directly indicate calcium intake among the Canadian or British Columbian population. Sampling The sample of participants selected for this study constitutes a convenience sample, that is, a sample selected from a population that was readily available. This method was chosen for sample selection because a random list of individuals with self-reported lactose intolerance is not available. Surveying physicians to recruit individuals with lactose intolerance from patient populations would have introduced bias into the sampling method as the study focus was self-reported and not physician diagnosed lactose intolerance. The disadvantage of a convenience sample lies in the inability to determine the representativeness of the sample data to the population data. Results are considered less definitive than i f determined from a random population. However, it is generally thought that information collected from convenience sampling can provide fairly significant insights and act 134 Chapter V : Discussion as a good data source in exploratory research. Results of the study must be qualified by careful interpretation and extrapolation to a limited larger population (Alreck & Settle, 1995). In this study, the procedure of convenience sampling and the requirement for fluency in English may have underrepresented individuals of ethnic minorities, despite advertising in a variety of ethnic community newspapers. This may account for the high proportion of Caucasian participants represented in the study, and provide a guide for future research to account for such a possibility. (Research indicates that individuals of Northern European descent and those of Caucasian background have high lactase levels that remain high throughout adulthood, while individuals of non-northern European descent become lactase non-persistent, (Suarez et al., 1995)). Alternately, it is possible that more Caucasians perceive and therefore self-report lactose intolerance. Assays performed to diagnose maldigestion would likely include more minorities, however symptom based diagnosis seems to include many Caucasians. This study can draw no direct conclusions with regards to ethnicity as the study used self-selection, not random selection. The increased prevalence of lactose intolerance self-reporting may be due more to voluntarism rates or self-selected participation among those of Northern European heritage. Additionally, researchers have found that supplement use is more common among Caucasian individuals (Slesinki et al., 1995). Since disproportionate amounts of Caucasians participated in this study, average calcium intake estimated in this study may be higher than what would be found if a greater proportion of individuals from minority backgrounds participated. Location of Study Recruitment of participants for this study was limited to participants residing within the Greater Vancouver Regional District. This location allowed for unique characteristics to enter 135 Chapter V : Discussion into the study, as the Vancouver locale is anecdotally reported to have unique characteristics with regards to individuals' perceptions of health and nutrition. The anecdotal reports of unique characteristics in Vancouver are supported by research on regional characteristics regarding health and nutrition concerns. Since the majority of the population in British Columbia resides in Vancouver, the characteristics unique to BC in this case can be regionalized further to associate the uniqueness with Vancouver. For example, attitudes towards milk are more negative among British Columbians, and British Columbians limit milk consumption more when compared to the Canadian average (Commins & Wingrove, 2000). Furthermore, individuals in BC who had medical concerns regarding milk, such as lactose intolerance or milk allergy, were more likely to limit milk consumption when compared to the national average. More individuals believed calcium could be obtained from non-milk sources, and more individuals limited milk consumption because of this belief when compared to the Canadian average (Commins & Wingrove, 2000). These unique characteristics may induce or predispose the study population to having calcium intake from food sources that differs from the larger population in Canada. Additionally, a greater proportion of British Columbians perceive that growth hormones are used to treat cows than the national average (Commins & Wingrove, 2000). Together, these findings substantiate the idea that data provided by British Columbians on lactose intolerance and attitudes towards milk and dairy products may be different from those in the larger Canadian population. As a result, the study therefore lacks generalizability to the larger population of individuals with lactose intolerance in Canada. 136 Chapter V : Discussion Vitamin D Assessment Vitamin D intake was not assessed in this study. Within the context of a survey, vitamin D could have been assessed as intake from food sources. Since vitamin D is found in relatively few foods in significant quantities, food sources of vitamin D could have easily been incorporated into the food frequency questionnaire used to assess calcium intake. Fortified milk, salmon, sardines and tuna are sources of vitamin D that were included in the questionnaire. Other items such as herring, margarine (fortified), and vitamin D supplements could have been incorporated into the FFQ. Including the assessment of vitamin D in this study would have provided insight into the ability of individuals to absorb calcium, as adequate vitamin D levels increase calcium absorption from the intestine to maintain serum calcium (Brown, 1995). The information however would not provide conclusive evidence on vitamin D status or to determine its influence on calcium absorption. It is difficult to quantify U V exposure, which is responsible for endogenous production of vitamin D. Theoretically, U V exposure during the winter months in Vancouver would be limited and therefore result in negligible amounts of vitamin D synthesis. However, U V exposure varies greatly through the year and therefore a determination based on winter months would not be representative of the whole year. Future studies should include vitamin D assessment in an effort to understand absorption of available calcium while understanding the assessment is not definitive. Interpretation of Questionnaire Items As in any type of survey research, it is possible that the questionnaire items may be interpreted in a variety of ways by different respondents. One such example of this phenomenon in this questionnaire is the statement "Milk and dairy products are natural foods." Some 137 Chapter V : Discussion participants may have interpreted this questionnaire item to mean that milk and dairy products are a natural part of the diet. Other participants may have interpreted this with respect to the processing of milk and dairy products, with the underlying idea that processed foods are unnatural. The implication of respondents assigning different meanings to words such as "natural" or interpreting questions in a variety of ways increases the variability of responses gathered by this research. Future studies should endeavour to pre-determine potential meanings assigned to questions used in survey design. Lack of Valid Testing One potential limitation of this study was the inability to differentiate between perceived and truly lactose intolerant participants. Due to time and financial constraints, as well as the specific focus of the study, participants were not requested to undergo any valid diagnostic protocol to determine their status as lactose intolerant maldigesters, nor were double blind challenges feasible to implement. This compromises the ability to classify participants as lactose intolerant maldigesters. However, while it is not possible to indicate which participants were maldigesters and which participants were intolerant, the focus of the study was perceived lactose intolerance, due to the likelihood that perceived intolerance may be more common than lactose intolerant maldigestion. Therefore, the inability to classify an individual participants' maldigestion has limited influence on the results of the study. Variable n for Analyses Not all participants provided complete information on all items in the questionnaire. Data were therefore excluded on a case by case basis for the different analyses performed, 138 Chapter V : Discussion causing some analyses to have a small valid number of participants who provided responses. The small n presented in certain analyses limits the generalizability of results, even within the study sample. This is particularly important in the case of analyses performed for total calcium intake, as only 60 of 104 participants provided sufficient information on calcium supplementation to include in total calcium intake estimations and comparison statistics. Generalizability would have been improved had the number of participants responding with sufficient information been greater. Implications for Professional Practice No significant difference was found in supplementary calcium intake between self-diagnosed and professionally diagnosed participants. This finding can be interpreted in several ways. First, many physicians do not discuss nutrition interventions with their patients, in part due to lack of nutrition education during medical training despite increasing evidence of the significance of dietary modification in disease prevention and management (Halsted, 1999; Truswell, 2000). Lack of patients' compliance with dietary intervention may also limit physician initiated nutrition discussions. However, physicians are a trusted information source (Truswell, 2000). The trust placed in physicians by the general public, in combination with lack of difference in calcium intake, indicates a need for physician education in nutrition topics. As part of continued medical education, physicians could be provided with current information on proposed tolerance of dairy products by most lactose maldigesters and on calcium supplementation. Physician referral of patients to registered dietitians for dietary guidance should be encouraged. Other interpretations of the same finding indicate that physicians should not be viewed as the primary information delivery source. The lack of significant difference in supplementary 139 Chapter V: Discussion calcium intake between self-diagnosed and professionally diagnosed participants, when combined with information sources reported by participants, indicates that focusing solely on physicians as an information source for lactose intolerance and calcium intake (food and supplements) is inappropriate. In addition to efforts directed to physicians, collaborative efforts by dietitians, healthcare providers and nutrition educators should aim to assess information available on the web and subsequently develop a list of sites where accurate and credible information is provided. Dietitians should be encouraged to play a pivotal role in educating patients via alternative information sources as evidence suggests these sources will play a key role in future information gathering efforts. Research has been performed to help lay people distinguish the difference between accurate and inaccurate information on the internet (Fallis & Fricke, 2002). By assessing information on internet sites that were found during a multi-search engine review performed in a manner described to be similar to those used by the lay population, a set of indicators have been developed that correlate well with accurate information (Fallis & Fricke, 2002). The presence of these indicators on a website does not guarantee accuracy, but provides a hallmark of websites that can be considered for further analyses in a professional setting (Fallis & Fricke, 2002). In combination with traditional guidelines for assessing written materials, the assessment of internet resources using these indicators can therefore provide a guideline for health professionals compiling lists of sites with accurate information (McCarthy, 2000). Guidelines for the use of internet resources in gathering information on lactose intolerance are not the only area of involvement for health professionals. The large range of calcium intake from supplements (10-3200 mg) suggests the need for development of clear, specific guidelines on supplement use for individuals with lactose intolerance. While current 140 Chapter V : Discussion thoughts promote consuming a wide variety of foods as the best way to meet nutrient needs, promote optimal health and reduce chronic disease risk, the dietetic profession supports supplement use in a limited context (American Dietetic Association, 2001). For example, supplementation of certain nutrients is thought to benefit some groups of individuals (American Dietetic Association, 2001). This includes: supplementation of folic acid for women capable of becoming pregnant, iron supplements during pregnancy, B12 supplements for persons over age 50 due to high prevalence of atrophic gastritis, and supplemental Vitamin D for the elderly with limited milk intake and sunlight exposure (American Dietetic Association, 2001). Individuals with lactose intolerance who follow a dairy-free diet are at increased risk of consuming calcium deficient diets, and fall within the set of individuals who may benefit from calcium supplements (American Dietetic Association, 2001). The position statement regarding supplement use states that individual dietary assessment is required to identify individuals with low intake and may benefit from supplements (American Dietetic Association, 2001). However, the present study identified that dietitians are infrequently used as a resource for lactose intolerance. Guidelines for supplement use should be developed and used in combination with tools to accurately assess calcium intake so that professionals can easily ascertain what level of supplementation to recommend to people on an individual basis. Future Research Assessment of Calcium Supplement Intake Calcium supplementation appears to be extensive and may be important to total calcium intake. Due to the small number of participants who provided sufficient data for analyses, 141 Chapter V : Discussion knowledge about calcium intake from supplementation may benefit from further exploration. The method by which calcium supplement intake was assessed examined the use of calcium supplements over a one week period only. The long-term intake of such supplements was not ascertained in this study. Given the potential for inconsistent use of supplements, long-term supplementation is of interest for future research. To minimize non-response by participants, efforts should be made to gather detailed information (supplement name, amount of calcium per supplement, frequency of supplement use: times taken daily/weekly/monthly) using a simple format. Extensive pre-testing should be performed to ensure adequate understanding of the format chosen to collect information on supplement use. Education In order to effectively enable individuals with self-reported lactose intolerance to meet their calcium needs while understanding the condition of lactose intolerance, education planning is essential. Future research should try to determine the impact of an education program for individuals with lactose intolerance. Different styles of education may be influential in addressing an individual's ability to meet their calcium AI's. From a population health perspective, all individuals with low calcium intakes should be provided with education to help them attain calcium intakes that meet the current AI's. Individuals differ in both interest and tolerance for education. Educational materials and messages should be developed to meet the learning and application needs of all individuals, not just individuals who are interested in learning. A focal point may include researching differences between individuals in the population who are interested and receptive in education, those who like and tolerate education, and those who dislike and are uninterested in 142 Chapter V : Discussion education. Information gathered may then be used to develop education materials for each different group. A trial of the various education materials could then be performed to determine effectiveness of education materials in changing an individual's ability to meet their calcium needs. Materials and messages planned for specific groups of individuals, as categorized above by interest in learning, may prove to be beneficial in improving calcium intake as they can be targeted towards appropriate audiences. 143 Chapter VI: Conclusions Conclusions An exploratory survey design involving individuals with self-reported lactose intolerance was used in this study. The group of individuals with self-reported lactose intolerance included symptomatic lactose maldigesters (true lactose intolerance); symptomatic lactose digesters (experience symptoms of intolerance that are not due to maldigestion); and asymptomatic digesters (experience physical complaints not caused by lactose intolerance). Consequently, the findings of this study should not be generalized to any specific group of individuals with self-reported lactose intolerance. However, health professionals working with individuals self-reporting lactose intolerance should consider the findings of this study when providing dietary counselling. 1. Estimated Calcium Intake • Estimated daily calcium intake of participants was 591 mg/day (+ 382 mg/day) from food sources alone. • Calcium supplements were consumed by 67% of the study participants. • Supplementary calcium provided 746 mg/day ± 703 mg/day. • Estimated total calcium intake of participants was 1313 mg/day ±711 mg/day. • Calcium intake from food sources, supplements, and food and supplementary sources combined (total calcium) did not differ by age group or gender. 2. Milk, yogurt, cheese and calcium fortified beverages contributed significantly to estimated daily calcium intake from food sources. Yogurt and cheese were tolerated by 144 Chapter VI: Conclusions about 45-49% of study participants and may therefore be effective in helping some individuals achieve their age-appropriate AI levels for calcium. 3. Supplementation significantly increased estimated daily calcium intake. The increase in estimated calcium intake appeared to increase the number of participants meeting their age-appropriate Adequate Intake levels for calcium, however the increase did not achieve statistical significance. (The number of participants meeting their AI level was not significantly greater than the number meeting their AI without supplements). 4. The belief (attitude) that dairy products contain antibiotics or growth hormones were prevalent in the population (54% and 81% respectively). 5. Among individuals with self-reported lactose intolerance, the prevalence of self-diagnosis and the use of symptom description rather than the use of clinically relevant tests in diagnosis of lactose intolerance may contribute to misdiagnosis. Recommendations • Dietary counselling should be provided to help individuals meet their AI for calcium using food sources; alternately, calcium supplementation should be encouraged among people with self-reported lactose intolerance who are unable to meet their needs using food sources. 145 Chapter VI: Conclusions • Physicians and other health professionals involved in diagnosis of lactose intolerance should be encouraged to discuss calcium needs, food sources of calcium and calcium supplementation with individuals self-reporting lactose intolerance to promote individuals' ability to meet Adequate Intake levels. • In order to facilitate a reduction in the potential for lactose intolerance misdiagnosis, physician education surrounding research literature on appropriate testing should be supported and encouraged. Further education should include information on assessment of individual calcium needs and good calcium sources (both dairy and alternative calcium sources). • Health professionals should consider individual's attitudes towards milk and dairy products when providing counselling to ensure adequate calcium intake. Counselling food changes within an individual's ideology of appropriate food choices may enhance the likelihood of incorporating dietary changes to meet the calcium AI. • Health professionals should be involved in sourcing internet based resources that provide accurate and reliable information. 146 Literature Cited Literature Cited Adbusters. 1999).Adbusters Web Site. (Available: http://adbusters.org/spoofads/food/milk/ [1999, December 8]. Alaimo, K., McDowell, M . A. , Briefel, R. R., Bischof, A. M . , Caughman, C. R., Loria, C. M . , & Johnson, C. L. (1994). 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Review of trends in food use in the United States, 1909 to 1980. J Am Diet Assoc, 81(2), 120-8. Woznicki D, Kava, R. Food for thought: can you trust your favourite magazine to tell you what to eat? Priorities (American Council on Science and Health) 8(2), 1996. Available: http:// www.acsh.org/publications/priorities/0603/accuracv.html. [2002, Accessed January 2002.]. Zuccato, E. , Andreoletti, M . , Bozzani, A. , Marcucci, F., Velio, P., Bianchi, P., & Mussini, E . (1983). Respiratory excretion of hydrogen and methane in Italian subjects after ingestion of lactose and milk. Eur J Clin Invest, 13(3), 261-6. 164 Appendix A: Lactose Content of Milk and Other Dairy Products 165 Table A. 1: Lactose content of milk and other dairy products* Product Lactose (g) M i l k d cup/250 mL)) Whole 9-12 2% 9-13 1% 12-13 Skim 11-14 Chocolate 10-12 Buttermilk 9-12 Evaporated 24-48 Sweetened condensed 31 -50 Lactaid (lactose-reduced low fat milk) 3 Goat's milk 11-12 Acidophilus, skim 11 Yogurt. Low fat (1 cup/250 mL) 4-17 Cheese (1 oz/30 mL) Cottage (112 cup/125 mL) 0.7-4 Cheddar, sharp 0.4-0.6 Swiss 0.5-1 Mozzarella, part skim, low moisture 0.08-0.9 American, pasteurized, processed 0.05-4 Ricotta (1/2 cup/125 mL) 0.3-6 Cream 0.1-0.8 Butter (1 pat) 0.04-0.5 Cream (1 tbsp/15 mL) Light 0.6 Whipping 0.4-0.5 Sour 0.4-0.5 Frozen Dairy Desserts (1/2 cup/125 mL) Ice Cream 2-6 Ice Milk 5 Sherbet 0.6-2 * Reproduced from Scrimshaw and Murray, 1988. Appendix B: Recruitment Posters and Advertisements 167 Appendix C: Ethical Acceptance Letter 169 Appendix D: Questionnaire 171 A n Exploratory Study of Lactose Intolerance The purpose of this study is to learn more about the experiences of people with lactose intolerance. In the questionnaire, we frequently refer to "milk and dairy products". "Milk" refers to skim, 1%, 2% and homogenized cow or goat's milk. "Dairy products" refer to all products made from milk (Some examples are: yogourt, sour cream, whipping cream, cheese, and ice cream). For this study, all you need to do is fill out this questionnaire. It will take about 20-30 minutes of your time. There are no right or wrong answers to the questions - we simply want to know about your opinions and experiences. Thank you in advance for your valuable opinions. Please return your completed questionnaire to the researchers using the postage pre-paid envelope provided. How You Decided You Were Lactose Intolerant Where did you first hear about lactose intolerance? How did you decide that you were lactose intolerant? Please list the symptoms of lactose intolerance that you experience: How severe are your symptoms if you drink one cup of milk with a meal? (Please circle your answer). Mild Somewhat mild Moderate Somewhat severe Severe Was a health care practitioner involved in your diagnosis? No, I made the diagnosis by myself. Yes - If so, who? Family Physician/Doctor Other Physician/Specialist Registered Dietitian/Nutritionist Naturopath 172 Lactose intolerance can be diagnosed in many ways. Were any of the following used to determine your lactose intolerance? Please check all that apply. Breath hydrogen test - Repeated breath samples taken after consuming a lactose drink. Description of my symptoms. Fecal pH analysis - Stool sample given after consuming a lactose drink. Blood glucose test - Repeated blood samples drawn to test for glucose after consuming a lactose drink. Intestinal biopsy - Needle sample of intestine taken for laboratory analysis. Other (Please list): Opinions About Lactose Intolerance Please indicate your answer to the following questions by checking "True", "False" or "Don't Know" beside the following statements: True (T) False (F) Unsure (U) When the enzyme that breaks down lactose is made in small amounts, or is not made at all, the body breaks down lactose poorly T F U When the enzyme that breaks down lactose is made in small amounts, or is not made at all, lactose may cause uncomfortable symptoms in the stomach or intestines T F U Symptoms of lactose intolerance may include: Bloating T F U - Cramps (abdominal pain) T F U Gas T F U Skin Problems T F U Headaches T F U Rumbling sounds in the intestines T F U Weight Gain T F U Loose Stools or Diarrhea T F U Lactose reduced products (ex. Lactaid™ milk) contain almost no lactose T F U 173 Opinions About Milk and Dairy Products Using the following scale, please circle the answer that best describes what you think about the statements listed below. E X A M P L E : Orange juice is a good source of Vitamin C Strongly Disagree Somewhat Disagree Neutral Strongly Agree STATEMENTS: Milk and dairy products are good sources of calcium. Strongly Somewhat Neutral Somewhat Strongly Disagree Disagree Agree Agree Milk and dairy products are an important part of a healthy diet. Strongly Somewhat Neutral Somewhat Strongly Disagree Disagree Agree Agree Milk and dairy products contain synthetic hormones (BST or BGH). Strongly Somewhat Neutral Somewhat Strongly Disagree Disagree Agree Agree Milk and dairy products are natural foods. Strongly Somewhat Neutral Somewhat Strongly Disagree Disagree Agree Agree Cows are being treated with growth hormones. Strongly Somewhat Neutral Somewhat Strongly Disagree Disagree Agree Agree 174 Milk and dairy products do not contain antibiotics. Strongly Disagree Somewhat Disagree Neutral Somewhat Agree Strongly Agree It is easy to get enough calcium without using milk or dairy products. Strongly Disagree Somewhat Disagree Neutral Somewhat Agree Strongly Agree I think nowadays that milk may be contaminated in some way. Strongly Somewhat Disagree Disagree Neutral Somewhat Agree Strongly Agree Milk, Dairy Products and Discomfort Which of the following can you eat or drink without feeling discomfort? Yes (Y) No (N) Pizza ( 2 slices) Y N Lasagna (1 piece) Y N Caffe latte (8 oz) Y N Sour cream (2 tablespoons) Y N Ice cream (1/2 cup) Y N Yogourt (1 small container) Y N Hard cheese - ex. Cheddar (2 pieces) Y N Soft cheese -ex.cream/cottage cheese (2 tablespoons) Y N Lactose reduced milk -ex. Lactaid™ milk (8 oz) Y N Creamer or milk in coffee or tea (1 tablespoon) Y N Milk with cereal Y N Milk (8 oz) Y N Never Use (NU) N U N U N U N U N U N U N U _NU N U N U N U N U 175 What You Eat W e w o u l d l i k e some in format ion about the foods y o u eat. F o r each o f the foods l is ted, please indicate h o w often y o u usua l ly eat a por t ion o f the s ize stated be low. I f y o u eat the food: -once or more per day, f i l l i n the number o f t imes per day. -at least once a week but less than once a day, f i l l i n the number o f t imes per week, -less than once a week, but more than once a month, fill i n the number o f t imes per month. -less than once a month or never eat it, put an " X " under "Don't Eat". Example: C h r i s eats a couple o f s l ices o f toast most morn ings and usua l ly has a sandwich , p i ta or bagel at lunch ; he doesn't l i ke b r o c c o l i (and almost never eats i t) ; has k i d n e y beans o r lent i ls about t w i c e a m o n t h and eats about 5 oranges a week. Foods Usual Portion Size Day Week Month Don't Eat B r e a d , ro l l s , bagel . 2 s l ices or 1 bagel 2 B r o c c o l i , c o o k e d 3/4 cup _ X _ K i d n e y beans, l i m a beans, lent i ls 1 cup _ 2 _ Orange (fruit, not j u i c e ) 1 m e d i u m 5 Number of Times You Eat These Foods Foods Usual Portion Size Day Week Month Don't Eat B r e a d , ro l l s , bagel . 2 s l ices o r 1 bagel B r o c c o l i , c o o k e d % cup K i d n e y beans, l i m a beans, lent i ls Vi cup Orange (fruit, not j u i c e ) 1 m e d i u m T a h i n i 2 T b s p B o k choy or kale , c o o k e d Vi cup 176 Foods Usual Portion Size Day Week Month Don't Eat Parmesan cheese 1 Tbsp Almonds !4 cup Pizza 2 slices Baked beans, soybeans, white beans Vi cup Ice milk, frozen yogourt (reg or low fat) Vi cup Pancakes/waffles, made with milk 3 medium Pudding, made with milk ! /2 cup Soft and semi-soft cheese such as feta, mozzarella, camembert 1 %" cube (reg or low fat) Soup, made with milk 1 cup Tofu, made with calcium 3 oz. Firm cheeses such as cheddar, Swiss, gouda (reg or low fat) 1 %" cube Processed cheese slices (reg or low fat) 2 slices Salmon, canned with bones Vi can Sardines, canned with bones Vi can Yogourt, fruit flavoured (reg or low fat) % cup Caffe Latte 12 oz M i l k - s k i m , 1%, 2% whole, buttermilk or chocolate 1 cup Calcium fortified beverages (ex. soy, rice, orange juice) 1 cup 177 Please answer the following questions about your eating patterns: Do you take a supplement that contains calcium? (Multivitamin/mineral pill, ViActive™ or CalBurst™ supplements, Sports/Power Bar™, Turns™, or canned meal replacements, ex. Boost™). No Yes, if so, please check supplement labels and fill in the following grid. Supplement Name Amount of Calcium (mg) Times/Day Days/Week Have you ever followed a vegetarian diet? No Yes - If yes, are you currently following a vegetarian diet? Yes No - Which foods do you avoid? (Please list): Finding Out About Lactose Intolerance What are your sources for information about lactose intolerance? (Please indicate for each of the following whether you have ever used or don't use the source.) Use/Have Used Don't Use Magazines/Newspapers Pamphlets Television Internet/Websites • Books Friends/Relatives Physician Naturopath/Homeopath Dietitian/Nutritionist Health food store Dairy Industry Other (Please list): Of the above list, which source was the most informative, or most helpful to you? 178 Appendix E: Original Attitude Statements and their References 180 Table E. 1: Original Attitude Statements and their References Statement Reference Milk and dairy products are good sources of calcium. BC Dairy Foundation, 2000b Milk and dairy products are an important part of a healthy diet. BC Dairy Foundation, 2000b Milk and dairy products contain synthetic hormones (BST or BGH). Barr, 1999 Milk and dairy products are natural foods. BC Dairy Foundation, 2000b Cows are being treated with growth hormones. Commins & Wingrove, 2000 Milk and dairy products do not contain antibiotics. Barr, 1999 It is easy to get enough calcium without using milk or dairy products. Barr, 1999; Commins & Wingrove, 2000 I think nowadays that milk may be contaminated in some way. Commins & Wingrove, 2000 181 Appendix F: Pre-Testing Questionnaire 182 A n Exploratory Study of Lactose Intolerance Please take a few minutes to answer these additional questions regarding the questionnaire on lactose intolerance. Your answers will help us identify where the changes may need to be made to the questionnaire. Thank you for your time and your participation. Was the covering letter clear? How much time did it take you to complete the survey? minutes Was this reasonable? Were any questions unclear? No Yes - Which ones? Was the print size appropriate? Yes No - Too small No - Too large Did you understand the instructions on page 5 that described how to fill out page 5 and 6? Yes No Comments: 183 Appendix G: Validity Testing 184 Calcium Calculator Validity Testing Background: It is important to use valid tools when assessing nutrient intake. The B.C. dairy Foundation published the Calcium Calculator™ as a method to assess daily dietary calcium intake. No literature to date has assessed the accuracy with which the tools estimated this intake. Purpose: This study attempted to validate the Calcium Calculator™ by comparing estimated calcium intake with daily dietary calcium intake from food records. Participants: A total of 42 participants (two male, 38 female) were recruited from an advanced metabolism course at Acadia University. Two participants (both female) failed to complete the study because they did not complete the food records. Method: Pilot study - Participants in the pilot study completed a one day food record and a Calcium Calculator™. A food record sheet was created specifically for the study and participants were provided with detailed instructions on how to keep food record. Participants also attended a fifteen-minute instruction period that demonstrated common food portions and provided guidelines on how to estimate the quantity of food and beverages consumed to increase the accuracy of food records. Validation study - Procedures were identical to the pilot study except that a three day food record was completed by participants (two weekdays and one weekend day). 185 Analysis: Calcium content of diet records provided by participants were analysed using "Nutrient Analysis" software (University of Prince Edward Island). Data were compiled in Microsoft Excel and analyzed using SPSS. Statistics included mean, median and range. Spearman's rho was used to compare mean estimated calcium intake from the Calcium Calculator™ with mean calcium intake from three 24 hour food records. Results: Data were not normally distributed. Mean calcium intake estimated from food records and the Calcium Calculator™ were 1046 ± 660 and 790 ± 604 (respectively) for the pilot study; 926 ± 353 and 825 ± 397 (respectively) in the validation study. Median calcium intake was lower when by the Calcium Calculator™ compared to food records in the validation study. It also estimated a larger range of intake. Spearman's rho indicated a high degree of correlation (0.65 and 0.74 for the pilot and validation study respectively) between calcium intake estimated by food records and the Calcium Calculator™. Discussion & Conclusions: The similar correlations identified between the pilot and validation study suggest that single or repeated records produce similar results. While the Calcium Calculator™ produced more variable results, its use as a single day assessment tool may predict calcium intake with known errors (underestimation of mean) for an individual. Limitations: It was unclear whether study participants or the research completed the Calcium Calculator™ for comparison with the food records. If completed by the researcher, bias may have been introduced. 186 Conclusion: The Calcium Calculator appears to accurately estimate calcium intake from food sources among the sample population. *Information presented with permission from J. Pilgrim, RDN and Dr. S.E. Hogan (Acadia University), personal communication 2002. 187 Appendix H: Reliability Test 188 Appendix: Reliability Test Reliability testing procedures and statistics were established to assess two aspects of reliability: 1. Test-retest reliability of individual items and scales (i.e., do people give the same answer when they respond at two different times?) Test-retest reliability measures the relationship between the scores that a person achieves when he or she takes the same test twice. The testing device is said to be reliable when the results are consistent from one time to the next with a moderate degree of relationship. A Pearson product moment correlation r>0.75 was chosen as a reference point for a moderate degree of relationship because the correlation is predictive with over 50% accuracy (Gravetter & Wallnau, 1998). 2. Scale internal consistency (i.e., whether people respond similarly to items in a scale assessing a given construct.) For example, in an attitude scale, one would expect someone who agreed that "I think that milk nowadays may be in some way contaminated" would also agree that "milk and dairy products contain synthetic hormones". Internal consistency is assessed using Cronbach's alpha, and values >0.80 suggest that a scale is internally consistent. A Cronbach's alpha of >0.80 is equivalent to a correlation of 0.80 (Trochim, 2002), which is more than a moderate degree of relationship (Gravetter & Wallnau, 1998). Design And Sample The reliability study used a test-retest design. A convenience sample of 15 self-selected participants was recruited to complete the questionnaire twice at a one-week interval. Participants were selected using recruitment posters and presentations at the University of British Columbia. Questionnaires were collected after each was completed. Twelve of the 15 189 participants completed the study protocol; two participants did not meet inclusion criteria and one participant did not complete the second questionnaire. Statistical Analysis Questionnaire reliability was assessed in two phases: item reliability and scale reliability. Pearson's product moment correlations were applied to data to examine test-retest reliability, and Cronbach's alpha was used to assess scale reliability. Results Test-retest Reliability Participants were able to provide multiple answers to each open-ended question presented in the questionnaire. The first response presented frequently differed between tests at the two time intervals. (What a participant listed as the first response in the first questionnaire was different from what they reported first in the second questionnaire). Reliability testing was therefore performed to assess whether the same symptoms (or other questionnaire item) were reported on both occasions. Table H. 1 reports test-retest correlations for the responses to the question "How did you first hear about lactose intolerance?" People reported anywhere from one to three responses in the first questionnaire, and the responses were compared to responses in the second questionnaire. The first response listed by participants received an acceptable correlation. 190 Table H. 1: Test-retest correlations for response options to "how did you first hear about lactose intolerance? How did you first hear about lactose intolerance? Correlation (r) I st response 0.850* 2 n d response 3 r d response *p<0.01 a. cannot be computed because at least one of the variables is constant. Table H.2 summarizes test-retest correlations for how participants decided they were lactose intolerant. Participants reported a range of one to three responses. Responses were correlated between the first and second questionnaire administration. Correlations ranged from 0.57-1.00. Table H.2: Test-retest correlations for a person's decision that they were lactose intolerant. How did you decide you were lactose intolerant? Correlation (r) 1st response 1.00* 2 n d response 0.567n s 4 / 3 , d response - a *p<0.01 ^does not meet criteria of r>0.75 a cannot be computed because standard deviation = 0 (there was no variation in responses). n s nonsignificant Table H.3 reviews the test-retest correlations for items presented by participants as their symptoms of lactose intolerance. Participants reported anywhere from one to six symptoms 191 experienced as symptoms of lactose intolerance, with a mean of 4.4 symptoms reported per person. A total of 53 symptoms was reported in both time 1 and time 2 of questionnaire administration. Correlations fell within a small range, from 0.99 - 1.00 and all correlations were significant at the p<0.01 level. This suggests that the number of symptoms reported, and the symptoms reported were very similar between administrations of the questionnaire at the two time intervals. Table H.3: Test-retest correlations for symptoms of lactose intolerance. Response Correlation 1st response 1.00* 2 n d response 1.00* 3 l d response 1.00* 4 t h response 0.99* 5 t h response 1.00* 6 t h response 1.00* *p<0.01 Table H.4 provides test-retest correlations for participant reported symptom severity, involvement of a health care practitioner in diagnosis of lactose intolerance, and the involvement of a second health care practitioner (if listed). One value did not meet the criterion of a correlation r>0.75. 192 Table H.4: Test-retest correlations for symptom severity with one cup of milk, and involvement of a health care practitioner in diagnosis of lactose intolerance. Item Correlation (r) Severity of symptoms following the ingestion of 1 cup milk 0.98* Involvement of a health care practitioner 0.97* Involvement of additional health care practitioner 0.70**T *p<0.01 ** p<0.05 ^does not meet criteria of r>0.75 Table H.5 recapitulates test-retest correlations for the use of diagnostic procedures in the diagnosis of lactose intolerance. Three values could not be calculated due to insufficient response variation. Table H.5: Test-retest correlations for use of diagnostic procedures. Standard Test Items Correlation (r) Other Test Items Correlation (r) Hydrogen breath test a Biopsy a Description of my symptoms 0.48 n s 4 / Vega test 1.00* Fecal pH a Allergy test 1.00* Blood glucose/lactose tolerance 0.78* Symptoms after a test consumption a cannot be computed because standard deviation = 0 (there was no variation in responses). *p<0.01 ' nonsignificant does not meet criteria of r>0.75 193 Table H.6 provides test-retest correlations for the questionnaire items from the lactose intolerance knowledge scale. Correlation values ranged from 0.60 - 1.00. Three values could not be calculated due to insufficient response variation. Table H.6: Test-retest correlations for items in the lactose intolerance knowledge scale. Statement Correlation (r) When the enzyme that breaks down lactose is made in small amounts, or is not made at all, the body breaks down lactose poorly - a When the enzyme that breaks down lactose is made in small amounts, or is not made at all, lactose may cause uncomfortable symptoms in the stomach or intestines 1.00* Symptoms of lactose intolerance include bloating 0.89* Symptoms of lactose intolerance include cramps (abdominal pain) - a Symptoms of lactose intolerance include gas - a Symptoms of lactose intolerance include skin problems 0.75* Symptoms of lactose intolerance include headaches 0.60** Symptoms of lactose intolerance include rumbling sounds in the intestines 0.89* Symptoms of lactose intolerance include weight gain 0.71 * Symptoms of lactose intolerance include loose stools or diarrhea 1.00* Lactose reduced products (ex. Lactaid™ milk) contain almost no lactose 0.62** People with lactose intolerance should completely eliminate all dairy products 0.66** a cannot be computed because standard deviation = 0 (there was no variation in responses). *p<0.01, ** p<0.05, ^does not meet criteria of r>0.75 194 Table H.7 presents test-retest correlations for the attitude scale items. Correlations ranged from 0.67 - 1.00. Two values did not meet the reliability criteria of r>0.75. Table H.7: Test-retest correlations of the attitude and opinion scale. Statement Correlation (r) 0.67** Milk and dairy products are good sources of calcium. Milk and dairy products are an important part of a healthy diet. 0.74* Milk and dairy products contain synthetic hormones (BST or BGH). 0.95* Milk and dairy products are natural foods. 0.82* Milk and dairy products are being treated with growth hormones. 0.90* Milk and dairy products do not contain antibiotics. 0.95* It is easy to get enough calcium without using milk or dairy products. 1.00* I think that milk may be contaminated in some way. 0.70*T *p<0.01 **p<0.05 T does not meet criteria of r>0.75 Table H.8 reviews the test-retest correlations for the items used to assess the potential discomfort caused by consumption of dairy products. Participants were asked to indicate which foods they could tolerate without discomfort. Correlations ranged from 0.24 - 0.94. 195 Table H.8 Test-retest correlations for milk, dairy products and discomfort scale items. Food Item Correlation (r) Pizza - 2 slices 0.90* Lasagna - 1 piece 0.83* Caffe latte -8 oz 0.89* Sour cream -2 tbsp 0.94* Ice cream - Vi cup 0.93* Yogourt - 1 small container 0.90* Hard cheese - 2 pieces 0.90* Soft cheese - 2 tbsp 0.59**4' Lactose reduced milk -8oz 0.24 n s T Creamer in tea/coffee 0.55 n s 4 J Milk with cereal 0.84* M i l k - 8 o z 0.71 *** *p<0.01, **p<0.05 y does not meet criteria of r>0.75,n s nonsignificant Table H.9 summarizes the test-retest correlations for the food frequency questionnaire items used in estimating calcium intake. The correlations ranged from 0.38-1.00. Monthly calcium intake had a high correlation (r=0.97), suggesting that the reporting of calcium intake, and therefore estimates of calcium intake, are stable over time. 196 Table H.9: Test-retest correlations of items used in the food frequency questionnaire for calcium intake estimation. Non-Dairy Sources of Calcium Dairy Calcium Sources Food Item Correlation (r) Food Item Correlation (r) Bagel, rolls, bread 0.88* Soup made with milk 0.97* Broccoli, cooked 0.91* Pizza 0.69*** Kidney & lima beans, lentils 0.79* Cottage cheese 1.00* Orange (fruit) 0.63**4' Ice cream 0.73* Tahini 0.99* Parmesan cheese 0.62**^ Bok choy kale (cooked) 0.99* Firm cheeses 0.64** Chickpeas 0.98* Soft/semi soft cheese 0.384'n s Almonds 0.68**T Processed cheese 0.97* Baked, soy & white beans 0.87* Pancakes/waffles with milk 0.95* Tofu made with calcium 0.76* Pudding made with milk 1.00* Canned salmon with bones 0.99* Ice milk & frozen yogourt 0.99* Canned sardines with bones 1.00* Yogourt, fruit flavoured 0.99* Calcium fortified beverage 1.00* Caffe latte 1.00* Milk - any % 0.76* Skim milk powder 1.00* Yogourt, plain 0.97* Amount of calcium/month 0.97* *p<0.01, ** p<0.05 ^does not meet criteria of r>0.75 n s nonsignificant 197 Table H. 10 summarizes test-retest correlations for the question grid used to assess participant use of calcium supplements and total amount of calcium consumed. A grid format was used to account for the intake of multiple supplements containing calcium. Test-retest correlations ranged from 0.93-1.00 for use of calcium supplements and intake from up to three sources. Table H. 10: Test-retest correlations for calcium supplement use. Item Correlation (r) Do you take a Ca supplement? 1.00* Supplement 1 (amount) 1.00* Supplement 2 (amount) 0.93* Supplement 3 (amount) 1.00* Total supplement value (amount) 0.93* *p<0.01 Table H. 11 indicates test-retest correlations for questions regarding vegetarian dietary practices among study participants. Test-retest correlations were 1.00 for each question. Table H. 11 Test-retest correlations for vegetarianism among study participants. Item Correlation (r) Have you ever followed vegetarian diet? 1.00* Are you currently following vegetarian diet? 1.00* Which foods do you avoid? (open ended) 1.00* *p<0.01 198 Table H.12 summarized test-retest correlations for information sources used by participants to learn about lactose intolerance. Correlations ranged from 0.63-1.00. Two values could not be calculated due to insufficient response variation. Table H.12: Test-retest correlations for reported information sources. Information Source Correlation (r) Magazines 0.63** Pamphlets 1.00* Television 0.60** Internet/Websites 0.83* Books/textbooks 0.84* Friends/relatives 0.84* Physician 1.00* Naturopath . 0.82* Dietitian 1.00* Health Food Store 1.00* Dairy industry 0.77* Other-journal articles - a Other-courses - a *p<0.01 **p<0.05 ^does not meet criteria of r>0.75 a cannot be computed because standard deviation = 0 (there was no variation in responses). 199 Table H. 13 presents test-retest correlations for sources indicated to be most informative, as reported by participants. Participants were allowed to provide multiple responses. Table H. 13: Test-retest correlations for most used sources. Most Used Source Correlation 1st response 1.00* 2 n d response 1.00* 3 l d response - a 4 t h response 0.72*T ______ ^does not meet criteria of r>0.75 a cannot be computed because standard deviation = 0 (there was no variation in responses). Table H . M review test-retest correlations for future information sources that participants would be most likely to use. Table UA4: Test-retest correlation for future information sources. Future Information Source Correlation 1st response 1.00* 2 n d response a *p<0.01 3 cannot be computed because standard deviation = 0 (there was no variation in responses). Table H. 15 summarizes the test-retest correlations relating to information needs of study participants. Correlations ranged from 0.62-0.83. Only one correlation fell within the acceptable 200 range of r>0.75. Information from this section is therefore not greatly reliable but may help identify some areas of concern for study participants. Table H. 15: Test-retest correlations for information needs statements. Information Needs Statement Correlation (r) What causes lactose intolerance? 0.68**4' How to manage symptoms of lactose intolerance? 0.69*** How to find out how much milk or other dairy products I can have without causing symptoms? 0.83* What foods I can eat in place of dairy? 0.58**T Do I need a supplement? 0.62**T *p<0.01 ~ **p<0.05 vdoes not meet criteria of r>0.75 Table H. 16 review the test-retest correlations for participant demographics. A l l demographic items received a correlation of 1.00. Table H. 16: Test-retest demographic correlations. Item Correlations Gender LOO* Age 1.00* Education 1.00* *p<0.01 2 0 1 Scale Internal Consistency Table H. 17 illustrates the internal consistency of the scales developed to assess knowledge, attitudes and opinions, discomfort and dairy product consumption behaviour. Cronbach's alpha values ranged from 0.86 - 0.91, with test-retest correlations ranging from 0.87 - 0.97,/?<0.01. These statistics indicate that the scales were internally consistent (reliable). Table H. 17: Scale internal consistency and reliability. Scale Alpha 3 Scale Correlation (r)b Knowledge 088 0.96* Attitudes 0.86 0.97* Discomfort and Consumption Behaviour 0.91 0.87* a Cronbach's alpha, a measure of internal consistency. b Pearson's product moment correlation, a measure of test-retest reliability. */?<0.01 Conclusions Internal Consistency Reliability testing indicated that all scales (Table H.17) exceeded the minimum value of alpha >0.80 set for Cronbach's alpha reliability test. These statistics signify that the scales were internally consistent (participants responded similarly to scale items). The scale items were therefore homogenous and measured the same construct (ie. knowledge, attitudes). Reliability Test Conclusions: Reliability testing indicated that the questionnaire scales measuring knowledge, attitude and behaviour achieved acceptable Cronbach's alpha-reliability coefficients (range 0.86-0.91) and Pearson's product moment correlations (range r=0.83-0.96,/?<0.01). The food frequency 202 questionnaire for calcium intake achieved a correlation of r =0.97, p<0.01. While not all items received an acceptable correlation to demonstrate reliability, the overall scale scores were within range. The questionnaire (individual items and scales) appears to be an appropriate, reliable tool to explore perceptions surrounding self-reported lactose intolerance. 203 Appendix I: Cover Letter 204 Appendix J: "Other" Ethnicities Listed Verbatim 206 Ethnicities listed: " Canadian" " British and French" " British and European" " Canadian" " French, native Indian, Scottish" " Chinese born Caribbean" " British and European" " British and European" " British and European" " Jewish" " Armenian" ' Ukranian" " Irish and Metis" " European and Caribbean" " British and European" " some aboriginal, unknown other mix (adopted)" " Canadian" " British and European" " Canadian" " British and European" " Caribbean - Chinese" " Jewish, British and European, Canadian" " Scottish, Jewish and Sephardic" " British and European" " Irish American, Cuban, Arabic and British" " Irish" " British and European" " French Canadian" " Canadian" " European and North American Aboriginal" " British and European" " European and Asian or Pacific Islands" " European and Latin, Central or South American" " Russian" " French Canadian" ' French Canadian Native" ' Russian" ' European and North American Aboriginal" ' Eurasian = Chinese, Dutch and Belgian" ' European and North American Aboriginal" ' British and European" ' Japanese, English, Irish, Welsh and Scottish" ' Russian Jew" Appendix K: Foods Avoided by Vegetarian Participants 208 List of other foods avoided by vegetarians: " organ meat, non-organic fruit and vegetables" " beans, sweetened dairy products, sweet and fatty foods" " olives, chocolate, candy, any chips which contain lactose" " wheat based foods" " soy products" " beans" " all nuts, snacks, candy, chocolate, sauces, corn, condiments" " corn and coffee" " processed foods, broccoli, strong cheese" " anything starchy" " processed meat" "any food prepared with milk" " subway, tomato sauces" " only pork" " margarine, peas, coconut milk, spicy foods" " 'junk' food" " sugar" " processed cheese and most processed foods" " ice cream" Appendix L: List of Non-Associated Symptoms Reported by Participants 210 103 - wheezing when breathing deeply 105 - vomiting 106 - facial skin eruptions 107 - can't sleep i f milk product is taken in evening 111- vomiting undigested milk curds 114- pain in esophagus 115 - nausea 127 - vomiting 129 - burping, sticky mucous causing sinus blockage and coughing at night 140 - white spots on tonsils 141 - sweating 142 - burping, heartburn, headache, body discomfort, nausea 144 - nausea, vomiting 150 - constipation with cheese 151 - blotchy, itchy skin on face, 153 - headache, nausea 156 - slightly nauseous 178 - migraine headaches 183 - nausea, vomiting 185 - migraines 187 - nasal congestion, post-nasal drip, joint aches, 200 - coldness, shivering, overwhelming sleepiness 211 - nausea, light-headedness 211 212- constipation 219 - vomit 220 - foul breath 223 - break outs on my face 240 - simultaneous feeling of hunger and fullness 242 - vomiting 246 - desire to throw up 247 - disgusting taste in my mouth, bad breath, sense of needing to vomit 253- light headed 257 - phlegm in my throat 258 - nausea 265 - nausea 268 - sleepiness 269 - asthma 273 - nausea 275 - itchiness, red eyes, runny nose 279 - nausea 281 - ears feeling full, vertigo 212 Appendix M : Other Tests Used in Diagnosis of Participants (Verbatim Responses) Verbatim Responses 105 - "elimination diet - my doctor had me eliminate A L L dairy from my diet and then slowly add it back in" 112- "skin test showed positive reaction" 114 - "don't have/know proper words -1 would drink a liquid and have x-rays taken; upper and lower barium; tube in the anus to take pictures of my bowel" - colonoscopy 118 - "n/a, no medical test. Repeated measures design-self-diagnosis" 119 - "cannot recall the name - held onto a metal "bar", a vial with a sample of food item, placed on a machine which measured the tolerance" - vega test 129 - "allergic to milk or scratch test. I am not sure that I am truly lactose intolerant but I am certainly intolerant of most dairy foods" 136 - "genetic background" 137 - "pain of cramps from ingesting dairy products & gas & bloating (severe - all symptoms are)." 139 - "allergy test by allergist" 143 -"took lactaid, and the symptoms didn't happen. If I eat/drink even a small amount of dairy without lactaid I get the symptoms. That's enough to determine my condition." 144 - "allergist had me drink a lactose drink then monitored my symptoms" 151 - "After severe reaction to "mothers milk" as a baby, pediatrician put me on goat's milk" 167 -"food elimination" 168 - "description of symptoms and my giving up dairy products until next visit" 180 - "total withdrawl of all milk products, with abstinence bringing relief of symptoms" 183 - "visit to allergist" 214 189 - "fecal pH analysis with no drink (lactose) given" 194 - "colonoscopy" 195 - "fecal pH and blood glucose tests were used, but as a general physical" 197 - "physical symptoms after ingesting milk" 205 - "lactose drink followed by very severe symptoms made it unnecessary to follow with other tests. I cannot remember i f there were other tests" 217 - "feeling better not using" 218 - "elimination of food" 257 - "vega test" 259 - "process of elimination- with use of lactaid or when not eating or drinking food with lactose symptoms do not persist" 261 - "eliminated all lactose and then re-introduced it to see what would happen" 268 - "se l f 269 - "trial and error" 275 - "allergy testing" 276 - "ethnic race - as a high percentage of asian's do not have the lactase enzyme" [sic] 281 - "removal of dairy products from my diet" 283 - "can't remember" 284 - "elimination of ingestion of milk and milk products" 215 Appendix N : Other Information Sources Listed Verbatim By Participants for Finding Information on Lactose Intolerance 216 1. "Research in library" 2. "Medical journals" 3. "My body and how it reacts to dairy. A book or Dr. may say this, but my body may say that" 4. "Several of my family are also lactose intolerant so we compare notes" 5. "Medical news letter" 6. "Personal experience/experimentation" 7. "Trade shows" 8. "My own choices - i.e., Soy milk" 9. " A gastroenterologist (second opinion)" 10. "Pharmacist" 11. "Acupuncturist, osteopath" 12. "Medical journal, health magazine" 13. "Hospital librarian" 14. "Experimentation - feeling sick when I forget that have lactose intolerance and then regretting it" 15. "Trade shows" 16. "Trial and error - as I deal with lactose intolerance I learn about it" 17. "Reading of labels" 217 

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