RESUMO
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.