A 12-week double-blind randomized clinical trial of vitamin D3 supplementation on body fat mass in healthy overweight and obese women

Background: Vitamin D concentrations are linked to body composition indices, particularly body fat mass. Relationships between hypovitaminosis D and obesity, described by both BMI and waist circumference, have been mentioned. We have investigated the effect of a 12-week vitamin D3 supplementation on anthropometric indices in healthy overweight and obese women. Methods: In a double-blind, randomized, placebo-controlled, parallel-group trial, seventy-seven participants (age 38 +/- 8.1 years, BMI 29.8 +/- 4.1 kg/m(2)) were randomly allocated into two groups: vitamin D (25 mu g per day as cholecalciferol) and placebo (25 mu g per day as lactose) for 12 weeks. Body weight, height, waist, hip, fat mass, 25(OH) D, iPTH, and dietary intakes were measured before and after the intervention. Results: Serum 25(OH) D significantly increased in the vitamin D group compared to the placebo group (38.2 +/- 32.7 nmol/L vs. 4.6 +/- 14.8 nmol/L; P<0.001) and serum iPTH concentrations were decreased by vitamin D3 supplementation (-0.26 +/- 0.57 pmol/L vs. 0.27 +/- 0.56 pmol/L; P<0.001). Supplementation with vitamin D3 caused a statistically significant decrease in body fat mass in the vitamin D group compared to the placebo group (-2.7 +/- 2.1 kg vs. -0.47 +/- 2.1 kg; P<0.001). However, body weight and waist circumference did not change significantly in both groups. A significant reverse correlation between changes in serum 25(OH) D concentrations and body fat mass was observed (r = -0.319, P = 0.005). Conclusion: Among healthy overweight and obese women, increasing 25(OH) D concentrations by vitamin D3 supplementation led to body fat mass reduction.