9 Surprising Things Scientists Have Learned About Aging

7. The Gut Microbiome Changes Dramatically with Age and Affects Longevity

Scientists have discovered that the trillions of microorganisms living in our digestive system undergo significant changes as we age, and these alterations have far-reaching effects on health, immunity, and longevity. The aging gut microbiome typically becomes less diverse and shifts toward bacterial species associated with inflammation and disease, while beneficial bacteria that support immune function and produce important metabolites decline. This microbial dysbiosis contributes to "inflammaging"—the chronic low-grade inflammation that characterizes aging—and has been linked to increased susceptibility to infections, autoimmune diseases, and age-related conditions such as frailty and cognitive decline. Remarkably, research has shown that centenarians and other exceptionally long-lived individuals maintain more youthful gut microbiome profiles, with higher diversity and greater abundance of beneficial bacteria compared to their shorter-lived peers. Studies have also revealed that the gut microbiome influences aging through multiple mechanisms, including the production of short-chain fatty acids that support intestinal barrier function, the synthesis of vitamins and neurotransmitters, and the regulation of immune responses. Perhaps most exciting is the discovery that the aging gut microbiome can be rejuvenated through targeted interventions, including probiotic supplementation, dietary modifications, and even fecal microbiota transplantation. Animal studies have shown that transferring gut bacteria from young mice to old mice can restore immune function and extend lifespan, while human studies have demonstrated that microbiome-targeted interventions can improve various markers of healthy aging, opening new possibilities for microbiome-based anti-aging therapies.