Abstract
Background: This study aimed to examine the evidence for the effect of Lepidium meyenii Walp. [Brassicaceae] (L. meyenii W.), known as maca, on improving semen quality. Methods: Nine databases were searched for randomized controlled trials (RCTs) that examined the parameters for improvements in semen quality, regardless of the type of L. meyenii W. The risk of bias (ROB) among the studies was evaluated according to the Cochrane ROB tool. Results: Five RCTs met all of the inclusion criteria. Three RCTs showed mixed efficacy of maca in improving semen quality parameters, including sperm concentration and sperm motility, in men experiencing infertility. The meta-analysis also failed to show the efficacy of maca in increasing the sperm concentration compared to the placebo (weighted mean difference, 2.22, 95% confidence interval -2.94 to 7.37, p = 0.4). Two other RCTs also showed mixed effects of maca on several semen quality parameters in healthy men. Conclusion: The evidence from the included studies suggests unclear effects of maca on semen quality parameters in both men experiencing infertility and healthy men. However, the total number of RCTs and the total sample size were too small to draw firm conclusions.