How Gut Microbiota Influence Healthy Aging: Overview of Reviews.

Background: Gut microbiota plays a key role in the aging process, with age-related microbial shifts contributing to chronic inflammation, metabolic dysfunction, frailty, and cognitive decline. Despite growing interest, an integrated synthesis of how diet and lifestyle modifications influence gut microbiota remains limited. This overview of reviews summarizes the current evidence on how dietary and lifestyle interventions shape microbial composition and affect aging outcomes. Methods: Following the PRISMA guidelines, we searched PubMed and Scopus for English-language reviews (January 2023-October 2025) including human adults aged ≥ 18 years, evaluating dietary or lifestyle interventions, and reporting gut microbiota with healthy-aging outcomes. Quality of the reviews was appraised using the SANRA tool. Results: Mediterranean and plant-based diets, calorie restriction, and microbiota-targeted approaches such as probiotics, prebiotics, symbiotics, and fecal microbiota transplantation were associated with increases in short-chain fatty acid-producing bacteria, including Faecalibacterium, Bifidobacterium, Lactobacillus, and Akkermansia muciniphila, while reducing pro-inflammatory taxa. These changes were linked to improved metabolic and immune function, reduced inflammaging, lower frailty, and greater physical resilience. Cognitive benefits included decreased neuroinflammation and a lower risk of Alzheimer's and Parkinson's diseases. Conclusions: Maintaining microbial balance through targeted dietary strategies may support healthier, more resilient aging, offering practical insights for public health and clinical nutrition planning.