Vitamin E supplementation improves testosterone, glucose- and lipid-related metabolism in women with polycystic ovary syndrome: a meta-analysis of randomized clinical trials

Aim: This systematic review and meta-analysis assessed the effect of vitamin E supplementation on testosterone, glucose, lipid profile, pregnancy rate, hirsutism, and body mass index (BMI) in women with polycystic ovary syndrome (PCOS). Methods: A multi-database search was performed from inception to January 2022 for randomized controlled trials (RCTs) reporting the effects of vitamin E supplementation with or without another nutritional supplement on women with PCOS. A random-effects model was used to obtain mean differences (MDs) and its 95% confidence intervals (95%CI). Evidence certainty was assessed with GRADE methodology. Results: We meta-analyzed eight RCTs reporting vitamin E supplementation alone or combined with other individual substances like omega-3, vitamin D3, or magnesium oxide in adult women ≤40 years old with PCOS. Vitamin E supplementation reduced fasting glucose (MD: −1.92 mg/dL, 95%CI: −3.80 to −0.05), fasting insulin (MD: −2.24 µIU/mL, 95%CI: −3.34 to −1.14), HOMA-IR (MD: −0.42, 95%CI: −0.65 to −0.19), total cholesterol (MD: −18.12 mg/dL, 95%CI: −34.37 to −1.86), LDL-cholesterol (MD: −15.92 mg/dL, 95%CI: −29.93 to −1.90), triglycerides (MD: −20.95 mg/dL, 95%CI: −37.31 to −4.58), total testosterone (MD: −0.42 ng/mL, 95%CI: −0.55 to −0.29), and increased sex hormone-binding globulin (MD: 7.44 nmol/L, 95%CI: 2.68 to 12.20). However, it had no impact on female sex hormones, HDL-cholesterol, BMI, and hirsutism. Two RCTs assessed pregnancy and implantation rates with inconsistent results. The certainty of the evidence was very low to moderate. Conclusion: Vitamin E supplementation improves glucose, lipid, and androgenic-related biomarkers in women with PCOS.