Biologists have found that centenarians – people over 100 years old – have more unique intestinal microbes, which, according to researchers, help prolong life by stopping the growth of other, more dangerous types of bacteria that cause diseases. The results of the study are published in the journal Nature.

The community of microbes in the human gut plays an important role in maintaining health and changes with age. To find out the potential relationship between the composition of microorganisms and life expectancy, Japanese researchers led by Kenya Honda from the Keio University School of Medicine in Tokyo, together with colleagues from the United States, studied the composition of the intestinal microbiome in three groups of Japanese people.

The first group consisted of 160 centenarians aged over 100 years, the second — 112 elderly people aged 85-89 years, and the third – 47 young people aged 21 to 55 years. The researchers took samples of fecal microbiota from all participants for analysis.

It turned out that centenarians, compared with the elderly and young people, have more microbes that produce bile acids, inhibiting intestinal pathogens’ growth.

The researchers traced the biosynthetic pathways of the formation of secondary bile acids and identified the bacteria responsible for their production. One of them, Odoribacteraceae, is known as an effective producer of isoallolithocholic acid, which has antimicrobial action against many gram-positive intestinal pathogens with multidrug resistance Clostridioides difficile and Enterococcus faecium.

Experiments on mice show that isoallolitocholic acid inhibits the growth of Clostridium difficile, a bacterium that causes severe diarrhea, especially in people receiving antibiotic treatment.

Scientists found other secondary bile acids in centenarians — isolitocholic, 3-oxolitocholic, allolitocholic, and 3 – oxoallolitocholic, and an increased level of the enzymes 5α-reductase (5AR) and 3β-hydroxysteroid dehydrogenase (3βHSDH), responsible for their production.

According to the authors, the constant high level of secondary bile acids in the intestine and its specific metabolism in centenarians reduce the risk of pathobiogenic infections and maintain healthy intestinal homeostasis. Researchers believe that it is due to a special intestinal metabolism that centenarians are less susceptible to age-related chronic diseases and infections than older people under 100.

The authors suggest that it is possible to use the bacterial strains identified in this study to metabolize bile acids to manage the pool of bile acids to improve health. However, they add that further research is needed to confirm the link between bile acids and longevity.