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 D 2 and vitamin D 3 are equally effective in increasing and maintaining serum concentrations of 25-hydroxyvitamin D [25(OH)D], particularly at lower doses of vitamin D. Objective: We aimed to investigate whether vitamin D 2 or vitamin D 3 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 D 2 , biscuit supplemented with 15 μg vitamin D 2 , juice supplemented with 15 μg vitamin D 3 , or biscuit supplemented with 15 μg vitamin D 3 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: Postintervention in the 2 ethnic groups combined, both the vitamin D 3 biscuit and the vitamin D 3 juice groups showed a significantly greater absolute incremental change (Δ) in total 25(OH)D when compared with the vitamin D 2 biscuit group [Δ (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 D 2 juice group [Δ (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 [Δ (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 D 3 was more effective than vitamin D 2 in increasing serum 25(OH)D in the wintertime. Vitamin D 3 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.