UBC Theses and Dissertations
Vitamin D intake and vitamin D status in 5 - 6 year old children in Vancouver Rasmussen, Betina Feldfoss
Vitamin D is important in maintaining bone health and has recently been proposed to have additional roles in the immune system and brain development. The estimated average requirement (EAR) and recommended dietary allowance (RDA) for vitamin D established by the Institute of Medicine (IOM) in 2011 is 10µg/day and 15µg/day, respectively. When this study was initiated, little information was available on whether vitamin D intakes below the recommendations in young children result in biochemical evidence of vitamin insufficiency or deficiency. Therefore the aims in this thesis were; to estimate vitamin D intakes in children, and the contribution of natural and fortified foods, and supplements; to determine the proportion of children consuming vitamin D below and above the intake recommendations; to use biochemical measures of plasma 25(OH)D to determine the proportion of vitamin D sufficient, insufficient and deficient children; and to estimate the importance of vitamin D intake and season to the children’s plasma 25(OH)D. This was a cross-sectional design with 200 children from Vancouver BC, aged 5.75 years. Vitamin D intakes were estimated using a food frequency questionnaire and 24 hr dietary recalls. Plasma 25 (OH)D was determined by HPLC-tandem mass spectrometry. The median vitamin D intake from foods was below the EAR and RDA. The children obtained 85.9% of their dietary vitamin D from supplements and fortified foods and 14.1% from natural food sources. Total median vitamin D intakes in children given or not given supplements was 13.0 (9.0) µg/day and 4.8 (3.7) µg/day, respectively, P< 0.001. Using the FFQ, 51% and 76% of the children did not meet the EAR and RDA for vitamin D, respectively. However, only 4.7% and 19.0% had a plasma 25 (OH)D below 40 nmol/L or 50 nmol/L, respectively. Unexpectedly, only 12.5% of the children who did not meet the EAR during winter months had a plasma 25 (OH)D below 40 nmol/L. The results in this thesis suggest that children depend on supplements and fortified foods to achieve the current vitamin D intake recommendations. However, despite apparent low vitamin D intakes, few children show biochemical evidence of vitamin D insufficiency, even during winter months.
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