Enterotypes

Enterotypes are proposed 'types' of gut microbial community. Think blood types, but for your gut bugs. Arumugam et al. (2011, Nature) first defined them. They used 39 metagenomes across six nationalities, with clustering math on stool DNA. They found three clusters, each named for a dominant genus. Enterotype 1 is Bacteroides-heavy. It is good at fermenting carbs and protein. Enterotype 2 is Prevotella-heavy. It leans toward mucin degradation and plant-rich diets. Enterotype 3 is Ruminococcus and Akkermansia, also mucin-degrading. The clusters looked independent of age, sex, and geography. But long-term diet nudged them: animal protein and fat toward Bacteroides, carbs toward Prevotella. The idea was quickly challenged. Knights et al. (2014) showed a person's enterotype can shift over time. That hinted at gradients, not sharp boxes. Costea et al. (2018) reconciled both views across many cohorts. Prevotella-dominated guts clearly separate from Bacteroides-dominated ones. But in-between communities grade smoothly. So you get two, three, or four clusters depending on the method. The aging link is indirect. Centenarians often show youthful Bacteroides-dominant profiles. And Prevotella and Faecalibacterium fade in the oldest-old. As of 2026, enterotypes help group people in diet studies. But they are not validated markers of biological age.

Last reviewed: June 22, 2026

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