Chicago, US: A nutritious diet has been shown to improve body weight, cholesterol levels, and heart health. Another component is the significance of nutrition in promoting healthy gut flora, according to a new study from the University of Illinois. According to the researchers, the Dietary Guidelines for Americans (DGA) promotes a gut microbial composition that may benefit general health.

"At the moment, there is no definition of a healthy microbiome." "Understanding how diet may influence the structure of the gut microbiota is important so that we can make dietary recommendations," says Alexis Baldeon, a doctoral student in the Division of Nutritional Sciences (DNS) at the University of Illinois. Baldeon is the paper's principal author, and it was published in The Journal of Nutrition.

The microbiota comprises billions of bacteria that dwell in the digestive system. They have a role in a variety of physiological processes, and varied gut microbiota may enhance resistance to perturbations that might lead to illness.

The researchers analyzed data from the American Gut Project, an extensive, crowdsourced database that includes faecal samples from thousands of individuals across the U.S. Their study focused on data from a subset of 432 healthy individuals divided into three groups according to how closely they followed the Healthy Eating Index (HEI), which is based on the DGA.

The group with the highest total HEI score, indicating the strongest compliance with the DGA, had the highest gut microbiota diversity, as well as a larger presence of bacteria that contribute beneficial functions like fibre fermentation, Baldeon says.

"The gut microbiota is really good at breaking down fibre, which is important because humans cannot digest fibre. Study participants with a higher diet quality had a greater abundance of bacteria involved in fibre metabolism," he notes.

Dietary guidelines and nutrient recommendations historically haven't included considerations for the microbiota. But that could change in the future, says Hannah Holscher, associate professor in the Department of Food Science and Human Nutrition at U of I and co-author of the study.

"Our work provides clues for specific microbes that may be relevant for monitoring the health of the microbiota and overall health," Holscher says. "Having your microbiome composition tested is currently not part of a standard physical examination. Even if you went out and got your microbiome sequenced today, your doctor or dietitian would not be able to give you strong, evidence-based recommendations from your results. But as we understand more about the interaction of diet, microbiota, and health, some gut microbes may become targets of our dietary recommendations. Just like we currently make recommendations to reduce sodium to lower your blood pressure or reduce saturated fat to lower your LDL cholesterol, our goal is to make dietary recommendations to nourish beneficial gut microbes."

Health policy is also starting to recognize the importance of the gut microbiome, the researchers say. Indeed, the scientific report for the latest DGA acknowledges that evidence from diet-microbiota studies should be considered in future dietary recommendations.

Holscher and Baldeon note their study supports the current DGA recommendations for a diet rich in fruits, vegetables and fibre. Following those guidelines, outlined in MyPlate, is still the best strategy for your overall health, including nourishing your gut microbes.