Vitamin D3 supplementation during weight loss: a double-blind randomized controlled trial

Area of Science:

• Endocrinology
• Nutritional Science
• Obesity Research

Background:

• Vitamin D deficiency is linked to obesity, but its role in weight management and related biomarkers requires clarification.
• Understanding the impact of vitamin D repletion on weight loss and obesity-related markers is crucial for public health.

Purpose of the Study:

• To compare the effects of vitamin D3 supplementation versus placebo on weight, body composition, insulin, and C-reactive protein (CRP) in postmenopausal women undergoing a weight-loss intervention.
• To investigate whether vitamin D repletion influences weight loss outcomes and associated biomarkers.

Main Methods:

• A randomized controlled trial involving 218 overweight/obese postmenopausal women (50-75 years) with baseline 25-hydroxyvitamin D [25(OH)D] between 10-32 ng/mL.
• Participants received either 2000 IU oral vitamin D3 daily or a placebo, alongside a structured weight-loss program (reduced-calorie diet and aerobic exercise) for 12 months.
• Outcomes including weight, body composition, serum insulin, CRP, and 25(OH)D levels were assessed using generalized estimating equations.

Main Results:

• Vitamin D3 supplementation significantly increased 25(OH)D levels compared to placebo (P < 0.0001).
• No significant differences were observed between groups in changes in weight, body mass index, waist circumference, body fat percentage, trunk fat, insulin, or CRP.
• Women who achieved vitamin D repletion (25(OH)D ≥32 ng/mL) experienced significantly greater reductions in weight (P=0.05), waist circumference (P=0.02), and body fat percentage (P=0.04) compared to those who did not.
• Adherent participants in the vitamin D arm showed a greater decrease in CRP levels (P=0.03).

Conclusions:

• Vitamin D3 supplementation, when combined with a weight-loss intervention, did not significantly improve weight loss or associated biomarkers compared to placebo alone.
• However, achieving vitamin D repletion during the intervention was associated with enhanced weight loss and body composition improvements.
• The findings suggest that optimizing vitamin D status may be beneficial for weight management in specific populations.