Effects of astaxanthin supplementation on human sperm quality during the freeze thaw process: a systematic review and meta analysis

The use of antioxidants in cryopreservation media has been shown to improve post-thaw sperm quality and male fertility in several credible meta-analyses. However, to our knowledge, no review has specifically examined the impact of astaxanthin, a potent antioxidant, on sperm quality after freezing. This meta-analysis and systematic review aims to investigate how astaxanthin affects sperm parameters during the freeze-thaw process. A thorough search of electronic databases (PubMed, Scopus, and Web of Science) was conducted up until July 1, 2024. Random-effects models were used to synthesize the data, and the quality and heterogeneity of the evidence were assessed. Our findings show that while astaxanthin improved sperm viability and morphology, there was no significant improvement in total motility (MD = 5.67, 95% CI: -7.49 to 18.84, p = 0.40) or DNA damage (MD = -12.07, 95% CI: -25.72 to 1.57, p = 0.08) after thawing. However, significant increases were observed in progressive motility (MD = 6.79, 95% CI: 3.37 to 10.21, p = 0.00) and sperm viability during thawing (MD = 7.56, 95% CI: 4.91 to 10.21, p = 0.00). Astaxanthin also significantly improved the percentage of sperm with normal morphology (MD = -24.53, 95% CI: -45.25 to -3.81, p = 0.02). Additionally, sperm kinematic parameters including VAP (MD = 3.71, 95% CI: 0.65 to 6.77, p = 0.02) and VCL (MD = 3.37, 95% CI: 1.19 to 5.54, p = 0.00) were significantly improved, while no significant differences were observed for VSL, LIN, and STR.A descriptive synthesis of redox status, metabolic activity, MMP measures, and apoptosis was conducted.These findings suggest that astaxanthin supplementation can significantly improve sperm viability, morphology, and certain kinematic parameters during the freeze-thaw process. However, due to the small sample sizes, risk of bias, and significant heterogeneity, further studies are needed to confirm these results.