More than Hormones? Metabolic Effects of Twelve-Week Probiotic Supplementation in Women with Polycystic Ovary Syndrome: A Secondary Analysis of a Randomized Double-Blind Placebo-Controlled Study

Background: Polycystic ovary syndrome (PCOS) is frequently associated with insulin resistance and dyslipidemia. Evidence regarding the metabolic effects of probiotics in PCOS remains inconsistent. This secondary analysis evaluated whether multispecies probiotic supplementation influenced glucose homeostasis, insulin resistance, and the lipid profile in women with PCOS. Methods: Data were derived from a 12-week randomized, double-blind, placebo-controlled study in which 50 women with PCOS were assigned to receive either a nine-strain probiotic (1.0 × 109 CFU/day) or placebo. Fasting and 120 min glucose and insulin concentrations, HOMA-IR, total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides were assessed at baseline and follow-up. Treatment effects were evaluated using analysis of covariance adjusted for baseline values. The main analysis was based on participants with available follow-up data, and an intention-to-treat sensitivity analysis including all 50 randomized participants was performed using multiple imputation for missing follow-up measurements. Results: Forty-three participants were included in the complete-case analysis (probiotic, n = 19; placebo, n = 24); seven did not complete follow-up (six in the probiotic group, one in the placebo group). No statistically significant between-group differences were detected for glucose homeostasis, HOMA-IR, or lipid profile. The intention-to-treat sensitivity analysis yielded findings consistent with the complete-case analysis. Conclusions: Twelve weeks of multispecies probiotic supplementation did not result in statistically significant improvements in glucose metabolism, insulin resistance, or lipid profile compared with placebo. Given the relatively small sample size and limited precision of some estimates, clinically relevant effects cannot be excluded. Larger randomized controlled trials are warranted.