In a new study, researchers identified distinct signatures in the gut microbiome that are linked to either healthy or unhealthy aging, which in turn predict survival in older individuals.
The research was conducted by a team at the Institute for Systems Biology.
The gut microbiome is an integral component of the body, but its importance in the human aging process is unclear.
In the study, the team analyzed gut microbiome data from over 9,000 people—between the ages of 18 and 101 years old.
The team focused, in particular, on longitudinal data from a cohort of over 900 community-dwelling older individuals (78-98 years old), allowing them to track health and survival outcomes.
The findings showed that gut microbiomes became increasingly unique (i.e., increasingly divergent from others) as individuals aged, starting in mid-to-late adulthood.
Strikingly, while microbiomes became increasingly unique to each individual in healthy aging, the metabolic functions of the microbiomes were carrying out shared common traits.
This gut uniqueness signature was highly correlated with several metabolites in blood plasma, including one—tryptophan-derived indole—that has previously been shown to extend lifespan in animals.
Blood levels of another metabolite—phenylacetylglutamine—showed the strongest association with uniqueness, and this metabolite is indeed highly elevated in the blood of centenarians.
The team says this unique signature can predict patient survival in the latest decades of life.
Healthy individuals around 80 years of age showed continued microbial drift toward a unique compositional state, but this drift was absent in less healthy individuals.
This uniqueness pattern appears to start in mid-life—40-50 years old—and is linked to a clear blood metabolomic signature, suggesting that these microbiome changes may not simply be diagnostic of healthy aging, but that they may also contribute directly to health as people age.
For example, indoles are known to reduce inflammation in the gut, and chronic inflammation is thought to be a major driver in the progression of aging-related morbidities.
This study highlights the fact that the adult gut microbiome continues to develop with advanced age in healthy individuals, but not in unhealthy ones, and that microbiome compositions associated with health in early-to-mid adulthood may not be compatible with health in late adulthood.
One author of the study is research scientist Dr. Tomasz Wilmanski.
The study is published in Nature Metabolism.
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