Resveratrol and male infertility: a systematic review of the literature.

Introduction: The aim of this study is to provide an updated and comprehensive systematic review on the effects of resveratrol (RSV) in male infertility and sperm preservation.

Evidence Acquisition: This systematic review followed the MOOSE guidelines for Meta-analyses and Systematic Reviews of Observational Studies and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA-P). Only original articles evaluating the effect of RSV on human spermatozoa in vivo or in vitro were included.

Evidence Synthesis: Of the 1806 abstracts evaluated for eligibility, only 12 studies were included in the qualitative synthesis, of which three were prospective in-vivo studies and nine were in-vitro studies. Out of three human studies on RSV, only two studies administered RSV alone, one of them reported a positive impact and the other reported no significant impact on semen parameters. Overall, the in-vitro studies have reported the ability of RSV to protect spermatozoa against damage due to freeze-thaw cycles during cryopreservation. Other in-vitro studies have reported positive effects of RSV in fresh samples and protective effects in cell lines.

Conclusions: Available in-vivo studies are controversial with regard to the effect of RSV in improving semen parameters. In-vitro studies support the use of RSV before sperm cryopreservation. Further well-designed prospective studies on large sample sizes are needed to fully understand the role of RSV in the treatment of male infertility in vivo.