Efficacy of probiotic and synbiotic supplementation on metabolic and endocrine parameters in polycystic ovary syndrome: a meta-analysis of randomized controlled trials.

BACKGROUND

This systematic review and meta-analysis aimed to evaluate the effects of probiotic and synbiotic supplementation on insulin resistance, reproductive endocrine function, lipid metabolism, inflammatory response, anthropometric parameters, and oxidative stress in patients with polycystic ovary syndrome (PCOS).

METHODS

Databases including PubMed, Web of Science, the Cochrane Library and Embase were systematically searched from inception to March 19, 2026. The Cochrane Risk of Bias Assessment Tool (RoB 2.0) was used for study quality evaluation. Meta-analysis was conducted with RevMan 5.4 and Stata 17.0. The study was prospectively registered in PROSPERO (CRD420251125178) and reported following PRISMA guidelines.

RESULTS

Eleven randomized controlled trials involving 780 participants were included. Probiotic and synbiotic supplementation significantly reduced fasting insulin (MD = - 1.41, 95% CI: -2.76 to - 0.05), total testosterone (MD = - 0.19, 95% CI: -0.25 to - 0.12), triglycerides (MD = - 12.28, 95% CI: -24.21 to - 0.35), low-density lipoprotein cholesterol (MD = - 6.19, 95% CI: -10.08 to - 2.30), BMI (MD = - 0.49, 95% CI: -0.88 to - 0.10), and body weight (MD = - 1.07, 95% CI: -2.08 to - 0.05), while increasing high-density lipoprotein cholesterol (MD = 1.73, 95% CI: 0.40 to 3.06) and total antioxidant capacity (MD = 124.02, 95% CI: 40.49 to 207.54). No significant effects were observed for fasting glucose, HOMA-IR, QUICKI, FSH, LH, SHBG, DHEAS, total cholesterol, C-reactive protein, waist circumference, or hip circumference. The single prebiotic trial contributed only to the meta-analyses of BMI, body weight, and waist circumference. According to the GRADE framework, the certainty of evidence was high for Testosterone, TG, LDL‑C, HDL‑C, BMI, and body weight, moderate for fasting insulin, and low for total antioxidant capacity.

CONCLUSION

Probiotic or synbiotic supplementation significantly improves multiple clinical parameters in women with PCOS, including reductions in fasting insulin, total testosterone, triglycerides, LDL cholesterol, BMI, and body weight, while increasing HDL cholesterol and total antioxidant capacity. However, the effects on fasting blood glucose, HOMA-IR, and certain sex hormones remain unclear and require further validation. The single available prebiotic trial showed benefits only for BMI and body weight, but its evidence is limited.

CLINICAL TRIAL NUMBER: Not applicable.