Vitamin D 3 supplementation during weight loss : a double-blind randomized controlled trial 1 – 3

Background: Vitamin D deficiency is associated with obesity; whether repletion supports weight loss and changes obesity-related biomarkers is unknown. Objective: We compared 12 mo of vitamin D3 supplementation with placebo on weight, body composition, insulin, and C-reactive protein (CRP) in postmenopausal women in a weight-loss intervention. Design: A total of 218 overweight/obese women (50–75 y of age) with serum 25-hydroxyvitamin D [25(OH)D] $10 ng/mL but ,32 ng/mL were randomly assigned to weight loss + 2000 IU oral vitamin D3/d or weight loss + daily placebo. The weight-loss intervention included a reduced-calorie diet (10% weight loss goal) and 225 min/wk of moderate-to-vigorous aerobic activity. Mean 12-mo changes in weight, body composition, serum insulin, CRP, and 25(OH)D were compared between groups (intent-to-treat) by using generalized estimating equations. Results: A total of 86% of participants completed the 12-mo measurements. The mean (95% CI) change in 25(OH)D was 13.6 (11.6, 15.4) ng/mL in the vitamin D3 arm compared with21.3 (22.6,20.3) ng/mL in the placebo arm (P , 0.0001). Changes in weight [27.1 (28.7, 25.7) compared with –7.4 (28.1, 25.4) kg], body mass index (in kg/m: both 22.8), waist circumference [24.9 (26.7, 22.9) compared with 24.5 (25.6, 22.6) cm], percentage body fat [24.1 (24.9, 22.9) compared with 23.5 (24.5, 22.5)], trunk fat [24.1 (24.7, 23.0) compared with 23.7 (24.3, 22.9) kg], insulin [22.5 (23.4, 21.7) compared with 22.4 (23.3, 21.4) mU/mL], and CRP [20.9 (21.2, 20.6) compared with 20.79 (20.9, 20.4) mg/mL] were similar between groups (all P . 0.05). Compared with women who achieved 25(OH)D ,32 ng/mL, women randomly assigned to vitamin D who became replete (ie, 25(OH)D $32 ng/mL) lost more weight [28.8 (211.1,26.9) compared with25.6 (27.2,25.0) kg; P = 0.05], waist circumference [26.6 (29.3, 24.3) compared with 22.5 (24.6, 22.0) cm; P = 0.02], and percentage body fat [24.7 (26.1, 23.5) compared with 22.6 (23.9, 22.2); P = 0.04]. Among women with complete pill counts (97% adherence), the mean decrease in CRP was 1.18 mg/mL (46%) in the vitamin D arm compared with 0.46 mg/mL (25%) in the placebo arm (P = 0.03). Conclusions: Vitamin D3 supplementation during weight loss did not increase weight loss or associated factors compared with placebo; however, women who became replete experienced greater improvements. This trial was registered at clinicaltrials.gov as NCT01240213. Am J Clin Nutr 2014;99:1015–25.