Researchers at Lund University in Sweden have discovered a new link between gut bacteria and obesity. They found that certain amino acids in our blood may be linked to both obesity and the composition of the gut microbiome.

We know less about the importance of our intestinal bacteria than many books and magazines on the subject would suggest. Much of the research on this topic is based on animal testing, which cannot be directly applied to humans. A healthy intestinal flora for one person does not necessarily have to be good for another person.

However, an increasing number of research studies show that our gut microbiota play an important role in our health. It affects our metabolism and can be linked to obesity, cardiovascular disease, and type 2 diabetes.

Previous studies have shown that people with these diseases have different metabolites; H. Small molecules, or metabolic debris, appear differently in the bloodstream. The aim of the new study was therefore to identify metabolites in the blood that can be associated with obesity (high body mass index, BMI) and to investigate whether these metabolites associated with obesity influence the composition of the bacterial flora in stool samples .

The researchers analyzed blood plasma and stool samples from 674 participants in the Malmö Offspring Study, MOS. They found 19 different metabolites that could be linked to the person's BMI. Glutamate and so-called BCAA (branched-chain and aromatic amino acids) had the strongest association with obesity.

They also found that the obesity-related metabolites were linked to four different gut bacteria (Blautia, Dorea, and Ruminococcus in the Lachnospiraceae and SHA98 family).

"The differences in BMI were largely explained by the differences in glutamate and BCAA levels. This shows that the metabolites and gut bacteria interact instead of being independent," says Marju Orho-Melander, professor of genetic epidemiology at Lund University .

By far the strongest risk factor for obesity in the study, glutamate, has been linked to obesity in previous studies, and BCAA was used to predict the future occurrence of type 2 diabetes and cardiovascular disease.

"This means that future studies should focus more on how the makeup of gut bacteria can be changed to reduce the risk of obesity and related metabolic and cardiovascular diseases," says Marju Orho-Melander. "To get there, we first need to understand what a healthy normal gut flora looks like and what factors affect bacterial composition. This requires extensive population studies such as the Malmö Progeny Study and intervention studies," she concludes.