The search for slower aging has brought scientists to an unexpected place: the human gut. Researchers at the University of Hawaiʻi at Mānoa found that certain intestinal bacteria are linked to how quickly the body ages, with microbial patterns explaining about 15% of variation in one biological aging measure.
Published in Scientific Reports, the findings offer another perspective on how the microorganisms inside us relate to the aging process. The discovery arrives amid growing interest in understanding biological age and whether it can be influenced.
The study involved 123 adults and examined whether bacteria in their digestive systems could help predict molecular signs of aging. Researchers identified two bacterial species associated with different aging patterns, though the findings do not show that either species directly affects how fast someone ages.
The research suggests gut bacteria may offer clues about biological aging, but scientists have not established whether changing them can slow the process.
Researchers Discover a Connection Between Gut Bacteria and Aging
The study found that differences in gut bacterial composition could help researchers predict one molecular measure of biological aging, offering new insight into the possible relationship between the microorganisms in our digestive systems and the pace of aging.
Researchers analyzed stool and blood samples from 123 participants aged 17 to 82. Stool samples revealed the composition of participants’ intestinal bacteria, while blood samples provided DNA methylation measurements associated with aging.
Using machine learning models called EpiBiome, the team investigated whether microbial patterns could help predict those measurements.
The strongest results involved DunedinPACE, a molecular measure designed to estimate the pace of biological aging rather than reflect someone’s chronological age.
The bacterial species model explained approximately 15.2% of the variation in DunedinPACE measurements. That figure describes the model’s statistical performance, not the percentage of aging controlled by gut bacteria.
“This study advances our understanding of the relationship between the gut microbiome and biological aging,” senior researcher Alika K. Maunakea said in the university’s announcement.
Related: Americans’ Gut-Healthy Eating Habits Stay Flat Even as Probiotic Use Soars 287%
Two Bacterial Species Emerged From the Findings
Researchers identified distinct associations between specific bacterial species in the human gut and the pace of biological aging, with some microorganisms linked to slower aging patterns and others associated with faster aging, offering new insights into the relationship between the gut microbiome and the body’s aging process.
One species, Bifidobacterium adolescentis, showed the strongest association with slower biological aging. Another, Succinivibrio dextrinosolvens, was most strongly associated with faster biological aging. These findings help narrow future research by identifying specific microorganisms worth closer investigation.
Lead researcher Braden P. Kunihiro explained why the microbiome presents an interesting area of study. “The gut microbiome is highly responsive to lifestyle, diet, environment and other everyday exposures,” Kunihiro said in the university’s July 22 announcement.
That responsiveness makes the relationship worth examining, particularly as scientists investigate the biological processes associated with aging.
Four Aging Measurements Produced Different Results
Only one of the four molecular aging measures examined showed statistically significant predictive results from the gut bacteria models, suggesting that the relationship between gut bacteria and biological aging may depend on how aging is measured.
Researchers compared DunedinPACE with three other established measures: Horvath, Levine, and GrimAge2. These methods use DNA methylation patterns to examine different aspects of biological aging, but they do not all measure the same thing. Some estimate a person’s biological age, while others focus on aging-related health risks or how quickly the body is aging.
Among the four measures, DunedinPACE was the only one that showed statistically significant predictive results. The other three measures did not demonstrate the same relationship with gut bacteria. This distinction suggests that gut bacterial composition may be more closely associated with certain aspects of biological aging than others.
To strengthen their findings, the researchers also conducted 1,000 permutation tests. These tests involved repeatedly rearranging the data to determine whether the observed relationship could have occurred by chance. The results supported the statistical significance of the species-based model, giving researchers a specific association to investigate further.
However, the findings do not establish that gut bacteria directly influence the aging process. Additional studies will be needed to understand why DunedinPACE showed a significant relationship while the other three measures did not.
Why the Study’s Participants Matter
The research included participants from populations historically underrepresented in microbiome and aging studies, broadening scientific understanding of biological aging while highlighting the need for greater diversity in research on the relationship between gut bacteria and aging.
Participants were recruited in Hawaiʻi, with Native Hawaiian and Pacific Islander individuals accounting for approximately 63.4% of the sample.
Their inclusion allowed researchers to examine microbial aging patterns in populations that have received comparatively little attention in this field.
Study coauthor Ruben Juarez described the broader relevance of studying the microbiome. “The microbiome exists at the intersection of behavior, environment and human biology,” he said.
The study was published on July 14, 2026, and the university announced it on July 22. Its findings received renewed attention through ScienceDaily coverage on October 27.
What Scientists Still Need to Discover
The findings show a statistically significant relationship between certain gut bacteria and the pace of biological aging, offering researchers clues about how the gut microbiome may connect to aging. However, the study does not show that changing these bacteria can slow aging or extend human lifespan.
The researchers did not test treatments to modify participants’ gut bacteria or follow them to see whether specific microbial patterns affected lifespan.
Larger studies across different populations could help determine whether the observed relationships hold up.
For now, the discovery highlights a distinction between identifying biological patterns and understanding what they mean for everyday life.
The ability to measure aging is advancing, but determining whether those measurements can change remains a different challenge.
What might these discoveries reveal about the factors that shape how we grow older, and how could that understanding influence the future of aging research?
