Objective To systematically evaluate the effects of vitamin D supplementation on sex hormone levels in patients with polycystic ovary syndrome (PCOS), so as to provide scientific evidence for clinical treatment.

Methods Randomized controlled trials (RCTs) on vitamin D supplementation for treatment of PCOS were recruited by database searching including PubMed, Web of Science, EMBASE, and the Cochrane Library. Relevant information was extracted from each study, including the first author, publication year, metabolic status, endocrine indicators, and serum vitamin D levels in both experimental and control groups. Meta-analysis was used through RevMan 5.3 software, with weighted mean differences (WMDs) and 95% confidence intervals (CIs) calculated to assess the correlation between vitamin D supplementation and sex hormone levels.

Results A total of 14 RCTs were involved in our study. Meta-analysis results demonstrated that vitamin D supplementation significantly improved sex hormone levels in PCOS patients, specifically by reducing follicle-stimulating hormone (FSH), luteinizing hormone (LH), total testosterone, and estradiol levels, and the differences were statistically significant (P < 0.05). However, no significant improvement was observed in sex hormone-binding globulin (SHBG) and dehydroepiandrosterone (DHEAS) levels (P > 0.05).

Conclusion This study indicates that vitamin D supplementation significantly reduces the level of FSH, LH, total testosterone, and estradiol, improves their endocrine status in PCOS patients. However, due to limitations in both quantity and quality of involved studies, further high-quality, large-sample RCTs are needed to validate these findings.