Gut microbiome and extreme longevity: an in-depth study of Hainan centenarians

Aging is defined by multiple factors, of which genetics is thought to contribute up to 30%, while the environment contributes to around 70%. Animal studies demonstrated that, among other environmental factors, the gut microbiome significantly influences the lifespan of a host. Clinical studies of centenarians confirm this observation by establishing the distinct patterns of microbial populations between centenarians and other elders. A detailed description of the gut microbiome in healthy centenarians, thus, might be a key to new strategies to achieve longevity.

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Although the intestinal microbiota is recognized as one of the crucial health determinants, its detailed structure and mechanisms behind longevity in long-lived people are not fully understood. Most modern microbial studies are based on metagenomic sequencing (analysis of all genomes within a sample), which, due to the sample complexity, might lose information about microbial species with low abundance. To overcome this issue, Li et al. conducted a pioneering study that combined in-depth metagenomic sequencing with large-scale culturomics (cultivation of microbial species within a sample). 

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The study focused on the residents of Hainan island in the South of China – a fitting area for longevity studies due to its high incidence of centenarians, relatively homogenous population, unique diet, and lifestyle. The researchers analyzed the gut microbial structure from fecal samples of twenty-five healthy Hainan natives, including 12 centenarians and 13 seniors. From the assembled data, they were able to identify distinct microbial patterns of the longevous cohort. The results from both metagenomics and culturomics were found complementary. 

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The gut microbiome of the Hainan centenarians significantly differed from those of ordinary adults from the same region. The centenarians displayed a significantly decreased proportion of butyrate-producing bacteria and an increased population of so-called opportunistic pathogens: Escherichia coli, Desulfovibrio piger, and Methanobrevibacter smithii. While butyrate is connected with gut health in younger people, its abundance in elderly was found to have a negative impact. These bacteria are commonly found in the lower intestine and are generally harmless, although they can contribute to gastrointestinal diseases. All of these species show changes with aging, and this pattern was shared by centenarians in other regions. The researchers compared the abundance of these bacteria among people 18 to 106 years old to trace the patterns of age-related changes. All butyrate producers decrease with aging, while the abundance of opportunistic pathogens grows in older people. However, this growth is not consistent and, for the centenarians, is observed only at the earlier longevity stages (<85 years old).

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This, along with a decrease in butyrate producers, suggest that these bacteria play a role in longevity. Another distinct pattern is a higher number of Lactobacillus (probiotics associated with gut health) and Enterococcus (common commensal bacteria, mostly harmless) species in the centenarians. Altogether, these findings allow us to further develop our understanding of how the gut microbiome influences the life- and healthspan and pave the way for new longevity interventions.

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Source npj Biofilms and Microbiomes 

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