Serenoa repens and its effects on male sexual function. A systematic review and meta-analysis of clinical trials

Background: Serenoa repens (SR) is a plant used to treat benign prostatic hyperplasia and prostatitis. We know that SR act as a 5α-reductase inhibitor, moreover, several studies have proved that SR has anti-inflammatory and antioxidant properties. There is some belief among patients that SR may negatively impact male sexual function. Such belief is circulating in non-medical social networks and is perhaps maintained by patients as a result of incorrect web surfing. However, it is also possible that SR may exert a "nocebo" effect thus negatively impacting on the general well-being of patients. Objective: The aim of this study is to investigate whether SR is causing negative effects on male sexual function. Methods: To ascertain the effect of SR on male sexual function, we conducted a systematic review and meta-analysis, by performing an electronic database search in accordance with the PRISMA guidelines. Results: Out of 20 included papers, 8 papers reported comparisons of SR with placebo, and 7 studies reported comparisons of SR with tamsulosin. The standardized mean difference of changes from baseline scores of sexual function was not significantly different between SR and placebo (SMD: 0.43, 95% CI: 0.18 to 1.05; I^2 = 95%). Similarly, no significant mean differences in the Male Sexual Function-4 (MSF-4) test scores were found between SR and tamsulosin (SMD: -0.31, 95% CI: -0.82 to 0.19; I^2 = 90%). Conclusions: We found no statistically significant differences between negative effects on sexual function in patients treated with SR compared to patients who received placebo. The results of our meta-analysis are similar to those of other systematic reviews. Studies are warranted to ascertain whether any such effects might occur as a result of a nocebo effect.