This systematic review and meta-analysis aimed to evaluate soy isoflavones’ effectiveness on TT serum levels and FSH in women with PCOS.

A meta-analysis was performed by searching for RCTs in several databases. Of the four practices found, the eligibility criteria for evaluating the efficacy of soy isoflavones on FSH serum levels were met by three trials and TT by four trials. The Cochrane scale was used to assess the risk of bias. Fixed-effects and random-effects models were used to determine the overall effect. The χ 2 test and the I 2 index were used to evaluate RCTs’ heterogeneity.

Our results showed that soy isoflavones significantly decreased TT (weighted mean difference [WMD] − 0.14; 95% confidence interval [CI] − 0.2, −0.02; p = 0.016; I 2 = 89%, p < 0.001) but had no significant effect on FSH levels (WMD −0.25; 95% CI −0.54, 0.02; p = 0.06; I 2 = 0%, p = 0.85).

Although this meta-analysis results showed that soy isoflavones in women with PCOS decreased TT and had no significant effect on FSH, better and more valid studies are needed to confirm these results.