NEW YORK – Long-lived individuals who reach at least 100 years of age appear to have gut microbial communities that retain or reacquire features associated with those from much younger individuals, new research suggests.
"[O]ur study supports the idea that longevity is associated with the gut microbiome via certain youth-associated signatures," co-senior and co-corresponding authors Shuai Wang, a researcher affiliated with Guangxi Academy of Sciences and Lanzhou University, and Weifei Luo, a researcher with the Guangxi Free Trade Zone Aisheng Biotechnology Corporation and the Guangxi Academy of Sciences, and their colleagues wrote.
For a study published in Nature Aging on Thursday, the researchers used targeted 16S ribosomal RNA sequencing to profile gut microbial communities in fecal samples collected from 1,575 individuals from the Guangxi region of China, ranging in age from 20 to 117 years, including 297 centenarians between the ages of 100 and 117. They also followed a subset of 45 centenarians for a year and a half, tracking their microbiome patterns over time.
For the microbiome analyses, the team classified 314 individuals between the ages of 20 and 44 years into a "young" cohort, 277 participants ages 45 to 65 into a "middle-aged" category, 386 individuals, aged 66 to 85, into an "old" cohort, and 301 participants between the ages of 90 and 99 into a nonagenarian group.
As in prior studies, the researchers found that the older adult cohort tended to show an uptick in the presence of potential pathogens in their gut microbiomes, along with altered microbiome diversity and diminishing levels of beneficial gut bugs.
In contrast to young and middle-aged adults, who tended to have gut microbiome enterotypes driven by beneficial Bacteroides representatives, for example, they saw a shift to Escherichia-Shigella-driven enterotypes in the old and nonagenarian cohorts.
When the team focused on the exceptionally long-lived individuals, on the other hand, it found microbiome features shared with both the youth-associated and old age-associated cohorts, including microbial patterns similar to those found in both Bacteroides- and Escherichia-Shigella-driven enterotypes.
More broadly, the investigators noted that the centenarian gut communities typically contained lower-than-usual levels of pathobionts or inflammation-promoting bacteria, along with enhanced representation of Bacteroidetes microbes, enhanced evenness and stability, and microbial diversity patterns that more closely resembled gut microbiomes from younger than older individuals.
While certain gut microbiome features showed apparent ties to health status in individuals over 65, particularly those in relatively poor health, the overall gut microbiome patterns held across each age cohort. For example, the authors explained, "centenarians consistently had higher levels of Bacteroidetes or Bacteroides than other old adults."
Likewise, in the subset of centenarians followed over time, the investigators saw stability for potentially beneficial Bacteroides species, as well as an uptick in microbiome evenness and fewer differences from one individual to the next. Even so, they noted, centenarians with diminished microbial species evenness in their gut appeared particularly prone to gut microbial community fluctuations and instability as they got older.
"Our findings revealed that centenarians have unique enterotypes relative to their old adult counterparts, which combine signatures in young and old adult individuals and exhibit prominent features that show high similarity to young adults in terms of youth-associated microbial hallmarks," the authors reported, noting that centenarian microbiomes are "characterized by an initial evenness-associated microbiome stability and increase in evenness as well as stable Bacteroidetes abundance and elevated similarity to that of young individuals."