ABSTRACT
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 I2 = 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 I2 = 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.
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Key Findings
Menopause is a transitional period of a woman’s life that takes place after the last period. Complementary and alternative medicine that involves natural compounds and in particular, administration of phytoestrogens, are being studied. The results of various studies on the effect of phytoestrogens on menopausal symptoms are not consistent, which could be due to the differences in the type of isoflavone, administered doses, and treatment periods. This systematic review discusses the findings reported by studies investigating the effect of phytoestrogens on sexual function in menopausal women. Only one study on flaxseed was included in the review. It compared three groups of subjects who were given flaxseed muffins, dietary soy, or placebo. Analysis of covariance considering body mass index as a confounding variable showed no significant difference among groups. The MD of the score of the sexual domain of MENQOL did not indicate any significant differences between the flaxseed and placebo groups. While the authors concluded that flaxseed had no promising effects on menopausal conditions, only one study was reviewed which limits the results.