Vitamin D supplementation in the treatment of polycystic ovary syndrome: A meta-analysis of randomized controlled trials

Background: Vitamin D level is closely associated with the development of polycystic ovary syndrome (PCOS). We aimed to systematically evaluate the effects of vitamin D supplementation on patients with PCOS, to provide reliable evidence to the clinical treatment of PCOS. Methods: We searched PubMed, Medline, EMbase, Cochrane Library, Web of Science, WanFang, China national knowledge infrastructure(CNKI) and Weipu databases for randomized controlled trials (RCTs) on vitamin D supplementation for the treatment of PCOS. Two reviewers indepen-dently screened literature, extracted data and evaluated the risk of bias of included RCTs. RevMan 5.3 software was used for meta-analysis. Results: 13 RCTs with 840 PCOS patients were included finally. Meta-analyses indicated that vitamin D supplementation increase the serum vitamin D level[mean difference(MD) = 17.81, 95% confidence interval(CI) (10.65, 24.97)] and endometrial thickness [MD = 1.78, 95%CI (0.49, 3.06), P = 0.007], reduce the serum hs-CRP [MD =-0.54, 95%CI (-1.00,-0.08)], parathyroid hormone[MD =-14.76, 95%CI (-28.32,-1.19)], total cholesterol[MD =-12.00, 95%CI (-18.36,-5.56)] and total testosterone level [MD =-0.17, 95%CI (-0.29,-0.05)] (all p < 0.05). No significant differences in the SHBG level [MD = 1.33, 95%CI (-2.70, 5.36)] and mF-G score [MD = 0.04, 95%CI (-0.79, 0.86)] between vitamin D and control group were found (all p > 0.05). Egger's tests showed that there were no publication biases in every synthesized result (all P > 0.05). Conclusion: Vitamin D may be helpful to improve the endocrine and metabolism-related indexes in patients with PCOS. More high-quality studies with larger sample size are warranted to further evaluate the role of vitamin D supplementation in patients with PCOS.