Effect of vitamin D supplementation on hormones and menstrual cycle regularization in polycystic ovary syndrome women: A systemic review and meta‐analysis

Abstract Aim Polycystic ovary syndrome (PCOS) is a prevalent endocrine disease among women of childbearing age. Women with PCOS frequently experience reproductive complications, which are closely associated with the concentration of vitamin D. This systemic review and meta‐analysis were conducted to elucidate the possible effect of vitamin D supplementation in PCOS women on hormones, including Luteinizing hormone (LH), follicle‐stimulating hormone (FSH), the ratio of LH and FSH (LH/FSH), and the menstrual cycle regularization. Methods We searched PubMed, Web of Science, Ovid MEDLINE, Cochrane Library, and EMBASE for the relevant articles published up to January 2022. The pooled estimates were calculated using RevMan 5.4 software. Results Twelve studies involving 849 PCOS patients were included. Our study indicated that vitamin D supplementation could reduce serum LH (standard mean difference [SMD]: −0.41; 95% confidence interval [CI]: −0.54, −0.28; p < 0.01). Subgroup analysis identified that the supplementation of vitamin D ≤4000 IU/day (SMD: −0.69; 95% CI: −1.15, −0.23; p < 0.01), treatment time ≤8 weeks (SMD: −0.61; 95% CI: −0.95, −0.26; p < 0.01), and vitamin D co‐supplementation (SMD: −0.37; 95% CI: −0.65, −0.10; p < 0.01) were related to reduce serum LH level. In addition, vitamin D supplementation improved the regularity of menstrual cycle significantly (risk ratio [RR]: 1.35; 95% CI: 1.18, 1.54; p < 0.01). In stratified analysis, the significant effects only existed in dosage of vitamin D >4000 IU (RR: 1.62; 95% CI: 1.02, 2.57; p < 0.01), treatment time >8 weeks (RR: 1.41; 95% CI: 1.06, 1.87; p = 0.02) and vitamin D co‐supplementation (RR: 1.18; 95% CI: 1.03, 1.35; p = 0.02). However, vitamin D might have no effects on serum FSH (SMD: −0.05; 95% CI: −0.42, 0.32; p = 0.79) and LH/FSH (SMD: −0.24; 95% CI: −0.55, 0.08; p = 0.14) in PCOS patients. Conclusions Evidence from the existing randomized controlled trials indicated that vitamin D supplementation might improve the LH level and the menstrual cycle regularization but did not have any effect on FSH and LH/FSH levels in PCOS patients.