Daily supplementation with 15 μg vitamin D compared with vitamin D to increase wintertime 25-hydroxyvitamin D status in healthy South Asian and white European women: a 12-wk randomized, placebo-controlled food-fortification trial.

There are conflicting views in the literature as to whether vitamin D and vitamin D are equally effective in increasing and maintaining serum concentrations of 25-hydroxyvitamin D [25(OH)D], particularly at lower doses of vitamin D. We aimed to investigate whether vitamin D or vitamin D fortified in juice or food, at a relatively low dose of 15 μg/d, was effective in increasing serum total 25(OH)D and to compare their respective efficacy in South Asian and white European women over the winter months within the setting of a large randomized controlled trial. A randomized, double-blind, placebo-controlled food-fortification trial was conducted in healthy South Asian and white European women aged 20-64 y ( = 335; Surrey, United Kingdom) who consumed placebo, juice supplemented with 15 μg vitamin D, biscuit supplemented with 15 μg vitamin D, juice supplemented with 15 μg vitamin D, or biscuit supplemented with 15 μg vitamin D daily for 12 wk. Serum 25(OH)D was measured by liquid chromatography-tandem mass spectrometry at baseline and at weeks 6 and 12 of the study. Postintervention in the 2 ethnic groups combined, both the vitamin D biscuit and the vitamin D juice groups showed a significantly greater absolute incremental change (Δ) in total 25(OH)D when compared with the vitamin D biscuit group [Δ (95% CI): 15.3 nmol/L (7.4, 23.3 nmol/L) ( < 0.0003) and 16.0 nmol/L (8.0, 23.9 nmol/L) ( < 0.0001)], the vitamin D juice group [Δ (95% CI): 16.3 nmol/L (8.4, 24.2 nmol/L) ( < 0.0001) and 16.9 nmol/L (9.0, 24.8 nmol/L) ( < 0.0001)], and the placebo group [Δ (95% CI): 42.3 nmol/L (34.4, 50.2 nmol/L) ( < 0.0001) and 42.9 nmol/L (35.0, 50.8 nmol/L) ( < 0.0002)]. With the use of a daily dose of vitamin D relevant to public health recommendations (15 μg) and in vehicles relevant to food-fortification strategies, vitamin D was more effective than vitamin D in increasing serum 25(OH)D in the wintertime. Vitamin D may therefore be a preferential form to optimize vitamin D status within the general population. This trial was registered at www.controlled-trials.com as ISRCTN23421591.