Gut Microbial Dysbiosis and Male Reproductive Health: Current Insights and Future Directions.

Male infertility contributes to approximately half of all infertility cases, with a substantial proportion remaining idiopathic. Emerging evidence implicates the gut microbiome as a regulator of male reproductive health through a proposed gut-testis axis. Few studies have shown that gut microbial dysbiosis may impair sperm quality via multiple mechanisms, including disruption of endocrine function (e.g., reduced testosterone production), alterations in microbial-derived metabolites, and impaired testicular energy metabolism. Increased intestinal permeability and systemic inflammation may further compromise the blood-testis barrier, while translocation of bacterial endotoxins may also contribute to testicular damage. Collectively, these processes can disrupt spermatogenesis and negatively affect sperm parameters, such as concentration, motility, and morphology. Interventions that restore microbial balance, including dietary modulation, have shown potential in reversing these effects and improving reproductive outcomes. This review summarizes and evaluates current literature linking gut microbial dysbiosis to male reproductive dysfunction. Key methodological limitations and knowledge gaps are highlighted, providing a foundation for advancing the development of gut microbiome-based interventions to improve male reproductive health.