This study was carried out to evaluate the effects of vitamin D supplementation on the metabolic profiles of insulin-resistant subjects with polycystic ovary syndrome (PCOS). This randomized double-blind, placebo-controlled trial was conducted on 90 insulin-resistant women with PCOS. Participants were randomly assigned to three groups to intake either 4000 IU of vitamin D or 1000 IU of vitamin D or placebo (n = 30 each group) daily for 12 weeks. Vitamin D supplementation (4000 IU), compared with vitamin D (1000 IU) and placebo, led to significant reductions in total testosterone (−0.2 ± 0.2 vs. −0.1 ± 0.6 and +0.1 ± 0.2 ng/mL, respectively, p = 0.02), free androgen index (FAI) (−0.06 ± 0.12 vs. −0.02 ± 0.12 and +0.004 ± 0.04, respectively, p = 0.04), hirsutism (−1.1 ± 1.1 vs. −0.8 ± 1.2 and −0.1 ± 0.4, respectively, p = 0.001) and high-sensitivity C-reactive protein (hs-CRP) (−0.7 ± 1.4 vs. −0.5 ± 0.9 and +0.5 ± 2.4 mg/L, respectively, p = 0.01). In addition, we found significant elevations in mean change of sex hormone-binding globulin (SHBG) (+19.1 ± 23.0 vs. +4.5 ± 11.0 and +0.7 ± 10.4 nmol/L, respectively, p < 0.001) and total antioxidant capacity (TAC) (+130 ± 144 vs. +33 ± 126 and −36 ± 104 mmol/L, respectively, p < 0.001) in the high-dose vitamin D group compared with low-dose vitamin D and placebo groups. Overall, high-dose vitamin D administration for 12 weeks to insulin-resistant women with PCOS had beneficial effects on total testosterone, SHBG, FAI, serum hs-CRP and plasma TAC levels compared with low-dose vitamin D and placebo groups.

The current study was conducted to evaluate the effects of 2 different doses of vitamin D supplementation on metabolic profiles of insulin-resistant patients with polycystic ovary syndrome (PCOS). This randomized double-blind, placebo-controlled trial was performed on 90 insulin-resistant patients with PCOS according to the Rotterdam criteria aged 18-40 years old. Participants were randomly allocated into 3 groups to receive either 4 000 IU of vitamin D (n=30) or 1 000 IU of vitamin D (n=30) or placebo (n=30) per day for 12 weeks. Vitamin D supplementation (4 000 IU), compared with vitamin D (1 000 IU) and placebo, led to reduced fasting plasma glucose (-4.3±8.6 vs. -4.7±7.1 and +0.1±6.7 mg/dl, respectively, p=0.02), serum insulin concentrations (-2.7±2.7 vs. -1.4±4.2 and -0.1±4.1 μIU/ml, respectively, p=0.02), and HOMA-IR (-0.6±0.6 vs. -0.4±1.0 and -0.1±0.9, respectively, p=0.02). In addition, we found significant decreases in mean change of serum triglycerides (-10.3±7.3 vs. -3.6±14.5 and +6.9±23.8 mg/dl, respectively, p=0.001), VLDL- (-2.0±1.5 vs. -0.7±2.9 and +1.4±4.8 mg/dl, respectively, p=0.001), total- (-14.0±9.5 vs. -6.2±24.0 and +7.1±29.7 mg/dl, respectively, p=0.002), LDL- (-10.8±8.3 vs. -5.7±21.9 and +6.8±28.2 mg/dl, respectively, p=0.005), and total-/HDL-cholesterol ratio (-0.2±0.3 vs. -0.1±0.6 and +0.2±0.7 mg/dl, respectively, p=0.003) in the high-dose vitamin D group compared with low-dose vitamin D and placebo groups. Overall, vitamin D supplementation at a dosage of 4 000 IU/day for 12 weeks in insulin-resistant patients with PCOS had beneficial effects of glucose metabolism and lipid profiles compared with 1 000 IU/day of vitamin D and placebo groups.

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