Daily supplementation with 15 μg vitamin D2 compared with vitamin D3 to increase wintertime 25-hydroxyvitamin D status in healthy South Asian and white European women: a 12-wk randomized, placebo-controlled food-fortification trial

Background: There are conflicting views in the literature as to whether vitamin D2 and vitamin D3 are equally effective in increasing and maintaining serum concentrations of 25-hydroxyvitamin D [25(OH)D], particularly at lower doses of vitamin D. Objectives: We aimed to investigate whether vitamin D2 or vitamin D3 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. Design: A randomized, double-blind, placebo-controlled food fortification trial was conducted in healthy South Asian and white European women aged 20–64 y (n = 335; Surrey, United Kingdom) who consumed placebo, juice supplemented with 15 µg vitamin D2, biscuit supplemented with 15 µg vitamin D2, juice supplemented with 15 µg vitamin D3, or biscuit supplemented with 15 µg vitamin D3 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. Results: Post intervention in the 2 ethnic groups combined, both the vitamin D3 biscuit and the vitamin D3 juice groups showed a significantly greater absolute incremental change (D) in total 25(OH)D when compared with the vitamin D2 biscuit group [D (95% CI): 15.3 nmol/L (7.4, 23.3 nmol/L) (P , 0.0003) and 16.0 nmol/L (8.0, 23.9 nmol/L) ( P , 0.0001)], the vitamin D2 juice group [D (95% CI): 16.3 nmol/L (8.4, 24.2 nmol/L) (P , 0.0001) and 16.9 nmol/L (9.0, 24.8 nmol/L) (P , 0.0001)], and the placebo group [D (95% CI): 42.3 nmol/L (34.4, 50.2 nmol/L) (P , 0.0001) and 42.9 nmol/L (35.0, 50.8 nmol/L) (P , 0.0002)]. Conclusions: 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 D3 was more effective than vitamin D2 in increasing serum 25(OH)D in the wintertime. Vitamin D3 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