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UBC Theses and Dissertations

Assessment of the rate and determinants of vitamin B12 deficiency in South Asian and European women of childbearing age in Metro Vancouver Quay, Teo


Low maternal vitamin B12 (B12) status has been associated with an increased risk for adverse offspring health outcomes, including neural tube defects and insulin resistance. High rates of B12 deficiency have been reported in South Asians, who comprise one of Canada’s largest minority groups, and Canadian women of childbearing age. Comprehensive B12 status assessment should include multiple biomarkers to reduce the risk of misclassification. However, there is no consensus on the appropriate cut-off values to define chronic and marginal B12 deficiency. Our goal was to assess the rate and determinants of B12 deficiency in healthy South Asian and European women in Metro Vancouver using multiple biomarkers. We conducted a cross-sectional descriptive study in a convenience sample (n=207) of South Asian and European women (19-35y). Anthropometric measurements and questionnaire data on demographics, lifestyle and diet were collected. Vitamin B12 status was assessed using serum vitamin B12 (SB12), serum holotranscobalamin (holoTC) and plasma methylmalonic acid (MMA) as biomarkers. The association of lifestyle, social, dietary, and genetic variables with B12 status was examined using multiple regression models. Using conventional SB12 concentration cut-offs, 14% of participants with biochemical data (n=204) were classified with chronic deficiency (SB12 <148 pmol/L), and 20% with marginal deficiency (SB12 148-220 pmol/L). There were no ethnic differences in rates of deficiency. The rate of B12 deficiency dropped substantially (5-12% decrease) when cut-offs for alternate biomarkers (holoTC and MMA) were applied alone or in combination with SB12 to indicate functional deficiency. Vitamin B12 status was influenced positively by dietary B12 intake and B12 supplement use, and negatively by oral contraceptive use and first generation immigrant status. We observed a high rate (34%) of B12 inadequacy based on SB12 levels, indicating a potential need for peri-conceptional monitoring of B12 status. Risk factors associated with B12 deficiency should be further assessed to determine whether surveillance of at-risk groups is required. Multiple biomarkers should be applied henceforth in B12 status assessment, as SB12 alone may lack accuracy and may not be sensitive for detecting marginal deficiency. As such, further investigation into the appropriate cut-offs for MMA and holoTC is needed.

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