Microflora of centenarians

Bile acid-metabolizing bacteria helped centenarians maintain the balance of the microbiome

Anastasia Kuznetsova-Fantoni, N+1

The composition of the gut microbiome of centenarians includes a greater number of bacteria that metabolize primary bile acids into secondary ones, compared with other age groups. This conclusion was reached by Japanese scientists who analyzed the composition of the microbiota of feces in people of different ages. Researchers believe that secondary bile acids help centenarians prevent the growth of pathogenic bacteria and intestinal inflammation. The work of Sato et al. Novel bile acid biosynthetic pathways are enriched in the microbiome of centenarians accepted for publication in Nature.

In some countries, the number of centenarians, that is, people aged 90 and older, is much higher than the global average. For example, the inhabitants of Italy and Japan are famous for this. Scientists regularly conduct research with the participation of centenarians to understand how they differ from other people. It is believed that longevity is largely determined by genetic factors. Recently, researchers studied the genomes of Italian centenarians over 104 years old and other people. Scientists have found that the main differences between them relate to the gene associated with DNA repair. Its polymorphisms help to avoid the accumulation of genetic breakdowns inherent in the aging process for longer. In addition to genetic features, longevity is also determined by environmental factors, for example, the composition of the intestinal microbiota. In a study of Sardinian centenarians, scientists have shown that their microbiota affects the body's metabolism by increasing glycolysis and fermentation of short-chain fatty acids.

Japanese scientists led by Kenya Honda from Keio University hypothesized that centenarians have a special composition of the intestinal microbiome that helps them fight infections and other environmental stressors. They decided to analyze the intestinal microbiota of different age groups and included in the study centenarians (160 people), people 85-89 years old (112 people) and 47 participants aged 21-55 years. Stool samples were collected from all the subjects and the composition of the intestinal microbiome was determined.

It turned out that long-livers are characterized by bacteria of the genus Alistipes, Parabacteroides, Bacteroides, Clostridium and Methanobrevibacter, which are much less common in other age groups. One of the most widely represented bacteria in centenarians, Clostridium scindens, is involved in the conversion of primary bile acids into secondary ones. The researchers decided to additionally check the levels of bile acids in the feces of the participants. The total amount of bile acids in centenarians did not differ from other age groups, but the number of secondary bile acids (metabolites of henodeoxycholic acid) was statistically significantly increased (p<0.05). In experiments on mice, scientists have shown that one of these metabolites – isoallolitocholic acid – inhibits the growth of bacteria that cause intestinal inflammation.

Researchers believe that bacteria that metabolize primary bile acids help centenarians maintain the balance of the intestinal microbiota and prevent the growth of pathogenic bacteria and inflammation.

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