The huge and diverse community of microbes in the human gastrointestinal tract is intimately linked to many aspects of our health and well-being. Since discovering its importance, researchers have begun to identify links between specific health conditions or characteristics and certain gut microbes. These links include both beneficial and harmful relationships. For some examples, we know that bacteria that generate short-chain fatty acids can be very good for human health, while other bacteria like adherent-invasive Escherichia coli have been linked to gut inflammation.
Now, scientists have assessed health, diet, and microbiome data from almost 35,000 people in the UK and US. Computational tools were used to find associations between specific gut microbes and markers of health like blood sugar levels, body mass index (BMI), triglyceride levels, and cardiometabolic health indicators. The findings have been reported in Nature.
The researchers focused on 50 of 661 species of gut microbes that are not uncommon; are linked to good health; as well as 50 species that are linked to poor health. The data was from the microbiome testing company Zoe, and led to the creation of a scoring system that was used to rank all 661 of the gut microbiota on a scale of 0 to 1. A score closer to 0 is positively correlated to health markers, while scores closer to 1 are negatively correlated.
Favorably ranked gut microbes were found to be more common in people with lower BMIs and fewer diseases. Higher levels of unfavorably ranked gut microbes were found more often in those with obesity and disease.
Additional work showed that improvements in dietary habits increased the number of favorable microbes, while also reducing the levels of unfavorable microbes.
An increase in the levels of a gut bacterium called Bifidobacterium animalis, which is often found in dairy products, and other microbes called Lachnospiraceae bacterium and R. hominis that have previously been linked to a vegan diet, were beneficial, as was an increase in another unknown Lachnospiraceae bacterium that has been linked to a vegetarian diet.
Other previously uncharacterized microbes were also discovered, and more research will be needed to understand their significance. The authors also noted that this study has only identified correlations, and has not established causal links between a gut microbe and any specific health conditions.
Sources: Medical Express, Nature