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UBC Theses and Dissertations

Vitamin B6 status of young and older adult women in Metro Vancouver Ho, Chia-ling


Vitamin B6 (B6) plays an essential role in the metabolism of amino acids, synthesis of neurotransmitters, and regulation of energy homeostasis. B6 deficiency, plasma pyridoxal 5’-phosphate (PLP) concentration <20 nmol/L, has been associated with impaired immune responses and depression. Suboptimal B6 status, plasma PLP concentration between 20−30 nmol/L, has been associated with cardiovascular disease and cancer. A 19.4% prevalence of inadequate dietary B6 intake was reported among women aged 51−70 years and 9.6% women aged 19−30 years in the Canadian Community Health Survey 2004. However, there are very few data on biochemical B6 status among Canadian women. This thesis aimed to assess B6 status and to identify predictors of B6 status, in young and older adult women in Metro Vancouver, Canada. Vitamin B6 status in young adult women was assessed from an existing, descriptive, cross-sectional study with a convenience sample of 202 women aged 19−35 years in Metro Vancouver. Another descriptive, cross-sectional study was conducted in 223 older adult women aged 51−70 years in Metro Vancouver recruited by convenience sampling. B6 status was determined by fasting plasma PLP concentrations. Information on demographic and lifestyle characteristics and dietary intake was collected through questionnaires. The prevalence of B6 deficiency was 1.5% in young and 1.4% in older adult women. Suboptimal B6 status was 10.9% in young and 8.1% in older adult women. In both samples, the participants had high education levels and about 30% used B6-containing supplements. Body mass index, dietary B6 intake, and the use of supplemental B6 were significant predictors of plasma PLP concentrations in both samples. South Asian ethnicity was identified as a negative predictor of plasma PLP concentration in young adult women but a positive predictor in older adult women. Suboptimal B6 status was prevalent in convenience samples of young and older adult women in Metro Vancouver. Ethnicity, dietary B6 intake and the use of supplemental B6 should be considered as covariates for predicting B6 status in future studies. Considering the high socioeconomic status of the participants in this thesis, there is a need to investigate B6 status in a representative sample of Canadian women.

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