Effects of Cholecalciferol Supplementation on Glycemic Response, Lipid Profile, and Anthropometric Parameters in Premenopausal Women with Benign Breast Disease: A Double-blind, Placebo-Controlled Randomized Clinical Trial.

INTRODUCTION: Benign breast disease (BBD) is common in premenopausal women and is influenced by metabolic and hormonal factors. Vitamin D regulates cell proliferation, inflammation, estrogen synthesis, and metabolic balance, suggesting a potential role in breast health. This study investigated the effects of cholecalciferol on glycemic, lipid, and anthropometric outcomes in women with BBD. METHODS: In this double-blind, placebo-controlled trial, 48 women with BBD were randomly assigned to receive 50,000 IU of cholecalciferol weekly plus a daily calcium-carbonate tablet (500 mg) containing 200 IU of vitamin D3, or placebo for eight weeks. Fasting glucose, insulin, HOMA-IR, HOMA-B, QUICKI, and lipid profiles were measured at baseline and post-intervention. Anthropometric indices, including body weight, waist and hip circumferences, and body mass index, were assessed. Dietary intake and physical activity were evaluated as confounders. RESULTS: Vitamin D supplementation was associated with significant improvements in insulin sensitivity. Compared with the placebo group, participants receiving vitamin D had significantly lower fasting insulin and HOMA-IR, together with significantly higher HOMA-B and QUICKI values after the intervention. No significant between-group differences were observed in fasting blood glucose, serum 25-hydroxyvitamin D concentrations, the glucose-to-insulin ratio, lipid profile parameters, or anthropometric indices. Within the vitamin D group, reductions in body weight, BMI, waist circumference, and hip circumference were observed; however, these changes were not significantly different from placebo after adjustment for baseline values and covariates. CONCLUSION: Cholecalciferol supplementation may improve insulin sensitivity in premenopausal women with BBD, while no significant effects were observed on lipid profile or anthropometric outcomes compared with placebo during the 8-week intervention. Larger and longer-term randomized controlled trials are warranted to confirm these findings.