Gut Microbiota, Probiotics, and Aging: Molecular Mechanisms and Implications for Healthy Aging

Recent advances in microbiome research have highlighted that age-related physiological changes are closely shaped by shifts in the gut microbial community rather than by the passage of time alone. Aging is frequently accompanied by a decline in microbial diversity and the loss of short-chain fatty acid-producing taxa, changes that weaken the intestinal barrier and contribute to the persistent low-grade inflammation described as inflammaging. These alterations intersect with immune and metabolic pathways linked to immunosenescence, cellular senescence, and mitochondrial function. In contrast, microbial ecosystems enriched with butyrate-producing and polyamine-generating species have been associated with more stable epithelial integrity, improved metabolic flexibility, and balanced immune activity. Emerging findings also indicate that the gut microbiota communicates with peripheral organs through the gut-skin, gut-muscle, and gut-brain axes, influencing tissue-specific aging processes. Evidence from animal models and human studies shows that dietary modulation, probiotics, and other microbiota-directed approaches can partially restore microbial functions relevant to aging, although responses vary considerably across individuals. Interest is also growing in postbiotic strategies, including microbial metabolites and vesicle-based components, which may offer targeted effects without requiring colonization. By integrating these mechanistic and translational insights, this review outlines how the gut microbiota contributes to aging biology and discusses the potential for microbiome-based interventions to support healthspan.