Astaxanthin (AST), a potent antioxidant carotenoid, has been investigated for its potential to improve male reproductive outcomes; however, findings remain inconsistent. This systematic review and meta-analysis aimed to evaluate the ability of AST to improve male infertility-related outcomes in both animal models and human clinical trials. A comprehensive search was carried out in Web of Science, Scopus, and PubMed. Eligible studies assessed the effects of AST on semen quality or oxidative stress markers. The risk of bias was assessed via the SYRCLE for animal studies and Cochrane RoB 2.0 for clinical trials. Random- effects models were applied for the meta-analysis. Heterogeneity was evaluated by the I² statistic, and publication bias via Egger’s test and funnel plots. Ten studies met the inclusion criteria: three clinical trials and seven animal studies. The human meta-analysis showed no statistically significant improvements in any semen parameters compared with placebo, indicating very limited and low-certainty clinical evidence. In contrast, animal studies demonstrated clear and significant improvements in sperm count (MD = 27.15), motility (MD = 11.29%), viability (MD = 15.98%), and morphology (MD = − 6.78%), along with reductions in oxidative stress markers. In conclusion, AST shows clear reproductive benefits in animal models, but our meta-analysis found no significant effects on male semen parameters in humans, and fertility outcomes such as pregnancy rates were not assessed. Therefore, current human evidence does not support clinical efficacy, and future trials should specifically evaluate semen quality and clinically relevant reproductive endpoints.
Dehpahni et al. (Thu,) studied this question.