Effects of probiotics intervention on sperm parameters: A systematic review on literature

Background: Male infertility is a critical global health issue, often linked to oxidative stress and inflammation. Probiotics, known for modulating gut health, have been proposed as a potential intervention for improving male reproductive health. However, the evidence remains fragmented, necessitating a systematic review to consolidate findings. Objective: This study systematically evaluates the effects of probiotic interventions on sperm parameters, including count, motility, morphology, and DNA integrity, in human and animal models. Methods: Adhering to Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, databases such as PubMed, Scopus, and Cochrane Library were searched up to November 2024. Eligible studies included controlled trials evaluating the effects of probiotics on sperm parameters in humans and animals. Data extraction focused on study design, probiotic species, dosages, intervention durations, and outcomes. The risk of bias (RoB) was assessed using SYRCLE's RoB tool for animal studies and Cochrane RoB for human studies. Results: Fifteen studies (5 humans, 10 animals) met the inclusion criteria. Probiotic species, belonging predominantly to the genera Lacticaseibacillus, Lactiplantibacillus (both formerly Lactobacillus), Limosilactobacillus, and Bifidobacterium, significantly improved sperm count, motility, morphology, and antioxidant markers. Mechanistic insights highlighted reductions in oxidative stress and inflammation, and improvements in communication between the gut and testis. While findings were consistent, heterogeneity in study design and species used was evident. Conclusion: Probiotics show promise in enhancing sperm parameters, mediated through systemic reductions in oxidative stress and inflammation. However, standardized protocols and long-term studies are necessary to validate their efficacy and develop clinical guidelines.