Research shows that high-protein diets can affect gut microbiome and body composition

New research has shed light on the effects of high-protein diets on the gut microbiome and overall health. Despite increased protein intake in Western diets, particularly among athletes and obese individuals, the fate of undigested protein and its impact on human health remains largely unknown.

A new study, presented in ASM Microbe, explores how excess undigested protein in the colon can be fermented to produce beneficial metabolites, such as short-chain fatty acids (SCFAs), or lead to the production of harmful metabolites such as ammonia and sulfides, which are linked to gastrointestinal disorders and other health problems.

The research team conducted a series of experiments in mice, finding that a switch to a high-protein diet resulted in significant weight loss, reduced body fat and induced immediate changes in the gut microbiome.

The study also compared different protein diets to examine the effects of individual amino acids on the composition and activity of the gut microbiome. Notably, mice consuming aromatic protein rich in amino acids experienced the greatest loss of weight and fat mass compared to those on standard protein and protein diets rich in branched chain amino acids.

“These findings provide an essential foundation for understanding how protein diets affect the gut microbiome and open the door to further investigation into the role of diet in promoting a healthy gut and overall health,” said Samson Adejumo, Ph.D. PhD in Biology, University of Illinois Chicago. .

To dig deeper into the effects of amino acids in high-protein diets on gut bacteria, the team conducted a four-week experiment with 16 mice. Initially, mice were fed a standard chow diet for two weeks, followed by isonitrogenous protein-rich diets enriched with branched-chain or aromatic amino acids for the following two weeks.

Daily faecal samples and weekly measurements of body composition were collected to monitor changes in fat and lean mass. DNA was extracted from feces and sequenced to analyze microbial composition and dynamics during the study period.

Comparison of microbial composition across the four protein pools revealed different abundance and composition of microbial taxa after protein enrichment. Using machine learning techniques, researchers predicted protein diets based on gut microbial taxa with 97% accuracy, supporting the relationship between diet and microbiome changes.

In general, genera of gut bacteria responded differently to dietary changes, from regular carbohydrate diets to high protein diets, and most importantly, to different groups of amino acids.

The most substantial changes occurred in the branched-chain amino acid-fed group. Although it is too early to say definitively that high-protein diets caused all the observed changes in body composition and gut bacteria, the consistent pattern of changes strongly indicates a link between high-protein diets and changes in the gut microbiome.

The research was led by Adejumo at the University of Illinois Chicago’s Marcell Laboratory and was presented at ASM Microbe 2024 in Atlanta, Georgia on June 15, 2024.