A systematic review of 41 studies identifies gut bacteria associated with healthy aging and long life, offering new insights into how the microbes living in our intestines may influence health as we grow older.

The trillions of microorganisms living in the human gut may offer valuable clues to why some people age more healthily than others—and why some live to 100 and beyond.

A systematic review of 41 human studies has identified differences in gut microbiome composition among younger adults, older people and exceptionally long-lived individuals, including centenarians. The findings highlight the potential role of gut microbes in maintaining health, regulating inflammation and supporting essential bodily functions throughout life.

The review, titled Gut Microbiome and Healthy Ageing: A Systematic Review of Literature, examined research from several regions, including areas recognized for their populations of long-lived people. Although the studies varied in methods and populations, some common patterns emerged, particularly among centenarians.

Beneficial Gut Microbes May Support Healthy Aging

The gut microbiome is the diverse community of microorganisms, including bacteria, viruses, fungi and other microbes, that live primarily in the large intestine.

Far from being passive residents, these microorganisms help the body digest food, regulate immune responses, protect against harmful pathogens and produce important substances such as vitamins, amino acids and short-chain fatty acids. These substances contribute to normal metabolism, intestinal health and other physiological processes.

However, the composition of the gut microbiome changes throughout life. In some people, aging is associated with reduced microbial diversity, an increase in inflammation-promoting microorganisms and a decline in microbes that produce beneficial substances.

Such changes, collectively associated with a condition known as gut microbiome dysbiosis, may disrupt immune function and the intestinal barrier. They have also been linked to processes involved in age-related diseases.

The review emphasizes that these changes do not occur in the same way for everyone. A person’s health, diet, lifestyle, medication use and environment can all influence the types of microorganisms living in the gut.

What Can We Learn from People Who Live to 100?

One of the review’s notable findings was the repeated identification of certain bacterial groups in centenarians.

Researchers reported an enrichment of bacteria belonging to the genera Akkermansia, Alistipes and Parabacteroides in long-lived individuals across the studies examined.

These findings are particularly interesting because gut microbes can influence several biological processes associated with aging, including the production of beneficial metabolites, the regulation of inflammation and the maintenance of the intestinal barrier.

The review also identified differences in microbial functions related to amino acid breakdown, vitamin production, and pathways potentially involved in immune regulation and inflammatory responses.

Together, these observations suggest that the gut microbiome may be an important part of the complex biological picture behind healthy aging and exceptional longevity.

However, the presence of particular bacteria does not automatically mean they cause longer life. Researchers must still establish whether these microbial patterns actively contribute to longevity or partly reflect other factors, such as diet, genetics, lifestyle and overall health.

Why the Findings Matter

Understanding how the gut microbiome changes with age could help researchers develop new approaches to maintaining health and reducing the burden of age-related diseases.

The review included 41 eligible studies, with most using DNA-based techniques to identify and compare microorganisms. Twenty-four studies used 16S rRNA gene sequencing, 13 used shotgun metagenomic sequencing, three used both methods, and one used metaproteomics.

These techniques allow scientists to examine microbial communities in greater detail and investigate not only which microorganisms are present, but also the biological functions they may perform.

Nevertheless, the researchers noted limitations in the available evidence. The studies differed in their populations and methods, and geographic representation remained limited. These differences make it difficult to identify a single gut microbiome profile that consistently defines healthy aging across all populations.

Could Changing the Gut Microbiome Help Us Age Better?

Scientists are increasingly interested in whether modifying the gut microbiome could improve health in later life.

Probiotics can introduce selected microorganisms into the gut, although their effects and persistence vary. Fecal microbiota transplantation, which transfers a community of microorganisms from a donor, can produce more substantial changes in some circumstances, but the resulting microbial composition and long-term effects are not fully predictable.

Neither approach has been established as a proven method for extending human lifespan. More research is needed to determine which microbial changes are beneficial, which interventions can produce them safely and whether those changes lead to meaningful improvements in long-term health.

Future treatments may aim to target specific microorganisms or microbial functions more precisely, potentially helping to maintain a healthier balance in the gut as people age.

A Promising Research Direction, but More Evidence Is Needed

The growing body of research on the gut microbiome is expanding scientists’ understanding of the relationship between intestinal microorganisms and the aging process.

The findings from this systematic review suggest that certain microbial patterns may be associated with healthy aging and exceptional longevity. They also highlight the importance of studying the gut microbiome as part of a wider network of biological processes influenced by lifestyle, environment and overall health.

For now, the key message is clear: the gut microbiome is a promising area of aging research, but scientists have not yet established a specific microbial combination that can reliably extend human life.

As further studies clarify how gut microorganisms interact with the body’s immune, metabolic and inflammatory systems, researchers may gain new opportunities to support healthier aging and improve quality of life in later years.