Scientists rank intestinal bacteria beneficial to health

Research published in the journal Nature last Wednesday (12/10) classified hundreds of gut bacteria based on their relationship to human health and nutrition.

The study, carried out by scientists from ZOE Ltd. in the United Kingdom and the University of Trento, Italy, shows which bacteria are most associated with favorable or unfavorable health indicators and how they relate to dietary habits.

Research has identified billions of microbes that influence digestion, the immune system and metabolism. According to the researchers, although previous studies have suggested that diet and lifestyle shape these microbial communities, analyzes systematically linking specific species of bacteria to markers of health and diet quality are lacking.

To fill this gap, scientists gathered data from more than 34,000 participants in the ZOE Predict studies (a series of clinical trials conducted in the US and UK), combining information on the gut microbiome, eating habits, body weight and markers of cardiometabolic health.

How scientists created the bacteria classification

With this dataset, the group of researchers developed two classification systems: the ZOE 2025 Microbiome Health ranking and the ZOE 2025 Microbiome Diet ranking. These rankings assigned numerical values to bacterial species based on their association with overall health and diet quality.

In total, 661 microbial species have been listed. Species with more favorable rankings tend to appear more frequently in people with lower body mass index (BMI) and better health profiles, while those with unfavorable rankings appear more in groups with obesity and disease.

Bacteria associated with a healthier diet

Faecalibacterium prausnitzii.
Eubacteria siraeum.
Intestinal roseburia.
Agathobacter rectale.
Variable subdoligranulum.
Coprococcus eats.
Blautia wexlerae.

Many of them belong to bacterial groups known to produce short-chain fatty acids, compounds associated with gut health and reducing systemic inflammation.

In addition to the observational analysis, the authors observed that in dietary intervention clinical trials involving 746 participants, changes in eating habits that promoted a better diet were accompanied by an increase in favorable microbes and a reduction in unfavorable microbes over time.

The role of diet in the composition of the microbiome

Although the study does not prove causality, that is, it does not demonstrate that one bacteria causes better or worse health, it provides a robust map of the links between the microbiome, diet and health indicators.

This type of ranking can guide future research and, potentially, personalized nutritional interventions focused on gut health. In practical terms, the results reinforce the importance of healthy eating habits.

High-fiber foods and plant-based foods tend to favor microbes associated with better health indicators, as opposed to diets of low nutritional quality, which are associated with bacteria linked to greater disease risk.