Findings rest on three lines of evidence: cross-country health-associated correlations of CAG-170 across diseases; computational analysis highlighting CAG-170 as a key, yet uncultured, member of the hidden microbiome; and dysbiosis data showing lower CAG-170 levels accompany gut imbalance.

The study sees CAG-170 as a potential health indicator of gut microbiome status and a promising target for next-generation probiotics, though cultivating and delivering these bacteria poses significant challenges; optimizing culture conditions, such as supplying arginine, may help.

A large international study identifies CAG-170, a little-known gut bacterium, as consistently more abundant in healthy individuals worldwide, suggesting a protective role of this microbe in the gut ecosystem.

The research was led by Dr. Alexandre Almeida of the University of Cambridge and published on February 9, 2026, in Cell Host & Microbe.

Experts note the microbiome should be viewed as an integrated system, with future work focusing on nutritional clinical trials to understand how diet shapes microbiome–host health dynamics.

Lead author Dr. Almeida emphasizes that CAG-170 likely plays a central role in digestion and microbiome stability, with health correlations observed across diverse diseases and populations.

The publication includes a meta-analysis of the uncultured gut microbiome across more than 11,000 global metagenomes, featured in Cell Host & Microbe, marking a major data-backed effort.

The paper outlines therapeutic avenues such as developing next-generation probiotics and methods to culture and validate uncultured gut bacteria based on the meta-analysis.

Genetic analyses show CAG-170 can produce high levels of vitamin B12 and enzymes that break down carbohydrates and fibers, suggesting it may support other gut microbes rather than directly benefiting the human host.

Genomic data indicate CAG-170’s B12 production and carbohydrate/fiber-degrading capabilities, pointing to an altruistic role in the microbiome by feeding other beneficial microbes.

CAG-170 is known only from genetic fingerprints and has not been cultured in the lab, underscoring the importance of the hidden or uncultured microbiome and metagenomic approaches to study it.

An open question remains whether higher CAG-170 levels cause better health or are a consequence of it; intervention studies will be needed to determine if introducing CAG-170 reduces disease risk.