The Effects of Vitamin D Supplementation on Metabolic Status of Patients with Polycystic Ovary Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial.

Data on the effects of vitamin D supplementation on metabolic status of patients with polycystic ovary syndrome (PCOS) are scarce. The current study was conducted to evaluate the effects of vitamin D supplementation on metabolic status of patients with PCOS. This randomized double-blind, placebo-controlled trial was performed on 70 vitamin D-deficient (serum concentrations<20 ng/ml) women with phenotype B-PCOS according to the Rotterdam criteria aged 18-40 years old. Participants were randomly allocated into 2 groups to take either 50 000 IU vitamin D (n=35) or placebo (n=35) every 2 weeks for 12 weeks. Metabolic, endocrine, inflammation, and oxidative stress biomarkers were quantified at the beginning of the study and after 12-week intervention. After the 12-week intervention, compared to the placebo, vitamin D supplementation significantly decreased fasting plasma glucose (FPG) (-3.1±7.3 vs. +0.5±6.3 mg/dl, p=0.02), insulin (-1.4±3.6 vs. +2.6±7.0 μIU/ml, p=0.004), homeostasis model of assessment-estimated insulin resistance (-0.3±0.8 vs. +0.6±1.6, p=0.003), homeostasis model of assessment-estimated B cell function (-4.9±13.4 vs. +9.9±26.9, p=0.005), and increased quantitative insulin sensitivity check index (+0.01±0.01 vs. -0.02±0.05, p=0.007). Supplementation with vitamin D also led to significant reductions in serum high-sensitivity C-reactive protein (hs-CRP) (-0.7±1.4 vs. +0.5±2.1 μg/mL, p=0.009) and plasma malondialdehyde (MDA) levels (-0.1±0.5 vs. +0.9±2.1 μmol/l, p=0.01) compared to the placebo. Overall, vitamin D supplementation for 12 weeks in vitamin D-deficient women with phenotype B-PCOS had beneficial effects on glucose homeostasis parameters, hs-CRP, and MDA.