Effect of phytoestrogens on sexual function in menopausal women: a systematic review and meta-analysis

Objective: This systematic review and meta-analysis aimed to critically evaluate the effectiveness of phytoestrogens on sexual disorders and severity of dyspareunia.Materials and methods: Relevant studies were identified through a systematic search of major databases such as PubMed, Cochrane Library, ISI Web of Science, and Scopus up to 29 September 2017, without any time limit. Two independent reviewers screened all abstracts and full-text articles. The final version of Jadad scale was used for evaluating the quality of trials.Results: Soy did not have an effect on sexual function (standardized mean difference [SMD]=1.099 [95% CI: -3.033 to 0.835, p=0.265]; heterogeneity I-2=80%; p=0.006; random-effect model; three trials) but improved dyspareunia (p>0.05). Red clover showed no significant effect on sexual function (SMD=-0.087 [95% CI: -0.936 to 0.763, p=0.842]; heterogeneity I-2=0%, p=0.397; fixed-effect model; two trials) and sexual satisfaction (p>0.05). Phytoestrogens isolated from Lepidium meyenii, Foeniculum vulgare, and maritime pine bark as well as Trigonella foenum-graecum L. significantly improved sexual function. In contrast, phytoestrogens isolated from Korean red ginseng and flaxseed did not lead to significant effect on sexual function. The positive effects of Trigonella foenum-graecum L. were observed on libido.Conclusion: Phytoestrogens have various effects on sexual function. Published reports show that maritime pine bark, T. foenum-graecum L., and F. vulgare could be considered as agents to overcome sexual dysfunctions while soy, red clover, genistein, and flaxseed had no promising effects on these conditions.