Application of Herbal-Based Antioxidants in Human Sperm Cryopreservation: A Systematic Review and Meta-Analysis Study

Sperm cryopreservation (SC) is an acceptable laboratory procedure for long-term storage of sperm. However, this procedure causes sperm damage. This review aimed to systematically investigate the effects of herbal-based antioxidants (HBAs) application on sperm parameters during SC. Following determination of the main keywords and searching strategy, various databases were searched systematically. Primary and secondary screenings were applied based on inclusion/exclusion criteria. Finally, 27 randomized controlled trial studies using 15 different HBAs and involving 567 normal and 130 abnormal semen samples were included for the meta-analysis. HBAs administration before or during the SC process improved total motility (mean difference [MD]: -6.31 [95% confidence interval [CI]: -10.27, -2.34], p < 0.05), viability (MD: -1.21 [95% CI: -1.52, -0.89], p < 0.001), morphology (MD: -1.72 [95% CI: -2.89, -0.54], p < 0.05), reactive oxygen species (H₂O₂) (MD: 7.58 [95% CI: 3.90, 11.26], p < 0.001), DNA integrity (MD: -13.21 [95% CI: -19.94, -6.49], p < 0.001), and sperm DNA fragmentation (SDF) (MD: 3.76 [95% CI: 2.38, 5.14], p < 0.001) after thawing in normal specimens. In abnormal semen samples, the HBAs improved viability (MD: -8.54 [95% CI: -11.18, -5.19], p < 0.001), progressive motility (MD: -4.55 [95% CI: -7.37, -1.73], p < 0.05) and ameliorated SDF (MD: 3.76 [95% CI: 1.74, 5.79], p < 0.001). Also, HBAs had no effects on total motility (MD: -0.08 [95% CI: -3.29, 3.14], p > 0.05), and morphology (MD: -0.31 [95% CI: -0.71, 0.09], p > 0.05). Application of HBAs in cryomedia before and during SC can improve sperm parameters (including viability, motility, and morphology), decrease oxidative stress and SDF levels.