How diet quality affects the gut microbiota to promote health

Newswise – URBANA, Ill. – We know that eating a healthy diet affects body weight, cholesterol levels and heart health. A new study from the University of Illinois focuses on another component: the role of diet in supporting a healthy gastrointestinal microbiota. The researchers conclude that according to the Dietary Guidelines for Americans (DGA) a gut microbiota composition that can support overall health is maintained.

“Currently, there is no definition of a ‘healthy’ microbiome. It is important to understand the possible influence of diet on the structure of the microbiota in the gut so that we can make recommendations regarding nutritional approaches,” says Alexis Baldeon, doctoral student in the Department of Sciences of Nutrition (DNS), part of the College of Agricultural, Consumer and Environmental Sciences at U of I. Baldeon is the lead author of the paper, published in The Journal of Nutrition.

The microbiota is made up of the trillions of microorganisms that live in the gastrointestinal tract. They contribute to many physiological processes, and a diverse gut microbiota may promote resilience to perturbations that may contribute to disease.

The researchers analyzed data from the American Gut Project, a large crowd-sourced database that includes fecal samples from thousands of people across the U.S. Their study focused on data from a subset of 432 healthy people 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 overall HEI score had the highest gut microbiota diversity, indicating the strongest compliance with the DGA, as well as the presence of more bacteria that contribute beneficial functions such as fiber fermentation, says Baldeon.

“The gut microbiota is great at breaking down fiber, which is important because humans can’t digest fiber. Study participants with a diet quality higher in fiber metabolism had a greater abundance of bacteria,” he notes.

Historically, questions regarding the microbiota have not been included in dietary guidelines and nutrient recommendations. 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 to specific microbes that may be relevant to monitoring the health of the microbe and overall health,” says Holscher. “Testing your microbiome composition is not currently part of a standard physical exam. Even if you went out and sequenced your microbiome 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, microbes and health, some gut microbes may become targets for our dietary recommendations. Just as 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 nurture beneficial microbes in the gut. “

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

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

The paper, “Diet Quality and the Fecal Microbiota in Adults in the American Gut Project,” is published in The Journal of Nutrition [DOI: 10.1016/j.tjnut.2023.02.018]. In addition to Baldeon and Holscher, authors include Daniel McDonald, Antonio Gonzalez, and Rob Knight.

This work was supported in part by the USDA National Institute of Food and Agriculture under the Nutrition and the gut-brain axis: Implications for development and healthy aging grant (2019-38420-28973) and Hatch Project 1009249 (HDH), as well as the Edge of Excellence Program, Division of Nutritional Sciences, University of Illinois.

Leave a Reply

Your email address will not be published. Required fields are marked *