# Centenarian microbiome signature

When scientists study people who reach extreme old age, they keep finding a different gut microbiome. Two studies stand out. An Italian group (Biagi and Franceschi) looked at people aged 105 to 109. A Japanese team (Sato and colleagues) studied centenarians. The pattern holds up. The usual top gut bugs thin out. Those are Ruminococcaceae, Lachnospiraceae, and Bacteroidaceae. Normally minor, health-linked species grow instead. Those include Christensenellaceae, Akkermansia muciniphila, Eggerthella, Bilophila, and Synergistaceae. These long-lived guts also make an unusual bile acid. It is called isoallo-lithocholic acid (isoallo-LCA), and the Odoribacteraceae family makes it. This acid boosts regulatory T cells, which may calm body-wide inflammation. One big caveat. This is a snapshot, so it cannot prove cause and effect. The microbes might help people reach 100. They might just reflect a long-lived person's diet and genes. Or it might be survivor bias, since people who live that long have already escaped the diseases that kill most others. It is a promising lead. It hints that bile acids and the immune system are part of the longevity story. But it is not something you should act on yet.

## Sources

- Biagi E, Franceschi C, Rampelli S, Severgnini M, Ostan R, Turroni S, et al.. (2016). Gut microbiota and extreme longevity. Current Biology. https://doi.org/10.1016/j.cub.2016.04.016
- Sato Y, Atarashi K, Plichta DR, et al.. (2021). Novel bile acid biosynthetic pathways are enriched in the microbiome of centenarians. Nature. https://doi.org/10.1038/s41586-021-03832-5

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_Canonical: https://longevity-switzerland.com/en/glossary/centenarian-microbiome · Part of Longevity Cities · Updated 2026-06-22_