A geroprotective probiotic and its functional metabolite counteract inflammaging to extend healthspan.

The gut microbiome profoundly influences host aging, yet the specific microbes and mechanisms governing divergent aging trajectories remain elusive. In this study, we delineated enterotype-specific gut microbial remodeling during aging and developed a microbiome-based aging clock (MicroAge) to track biological aging trajectories. We identified Bifidobacterium pseudocatenulatum (B. pseudocatenulatum) as a candidate geroprotective species consistently depleted during aging across both sexes and multiple Chinese cohorts. In naturally aged mice, oral B. pseudocatenulatum monotherapy rescued intestinal homeostasis, mitigated multiorgan inflammaging, enhanced cognitive-motor performance and extended healthspan. Mechanistically, we characterized 5-aminovaleric acid betaine (5-AVAB) as a key B. pseudocatenulatum-derived metabolite whose levels decline physiologically in aging humans. 5-AVAB supplementation partially recapitulated a broad spectrum of the systemic benefits observed with B. pseudocatenulatum treatment, including improved cognitive and motor function and suppressed multiorgan inflammaging. Our findings identify the B. pseudocatenulatum-5-AVAB axis as a promising target for microbiome-based interventions to promote healthy aging.