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.

Last reviewed: June 22, 2026

This definition is educational and is not medical advice, a diagnosis, or treatment. Talk to a doctor about any health decisions. Read our full medical disclaimer