New research presented at ASM Microbe 2024 sheds light on the impact of protein-rich diets on the gut microbiome and overall health. Despite the growing popularity of high-protein diets, particularly among athletes and those with obesity, the effects of undigested protein on human health have remained largely unclear.
The study, conducted by a team led by Adejumo at Marcell lab, University of Illinois Chicago, explored how excess undigested protein in the colon can either ferment to produce beneficial metabolites like short-chain fatty acids (SCFAs) or lead to the production of harmful metabolites such as ammonia and sulfides, which are associated with gastrointestinal disorders and other health issues.
Through a series of experiments on mice, the researchers found that switching to a protein-rich diet led to significant weight loss, reduced body fat, and immediate changes in the gut microbiome. They compared different protein diets to assess the effects of individual amino acids on the composition and activity of the gut microbiome. Mice consuming aromatic amino-acid-rich proteins experienced the most significant weight and fat mass loss compared to those on standard protein and branched-chain amino-acid-rich protein diets.
In a 4-week experiment involving 16 mice, the team fed them a standard chow diet for two weeks followed by protein-rich diets enriched with either branched-chain or aromatic amino acids for the next two weeks. They collected daily fecal samples and conducted weekly body composition measurements to monitor changes in fat and fat-free mass. DNA extracted from the feces was sequenced to analyze microbial composition and dynamics.
The comparison of microbial composition across the four protein groups revealed significantly different abundance and composition of microbial taxa after protein enrichment. Using machine learning techniques, the researchers accurately predicted protein diets based on gut microbial taxa with 97% accuracy, supporting the link between diet and microbiome changes.
The study found that gut bacteria genera responded differently to dietary changes, particularly from regular carbohydrate diets to protein diets and different amino acid groups. The most pronounced changes were observed in the group fed branched-chain amino acids. While it’s premature to definitively conclude that protein diets caused all observed changes in body composition and gut bacteria, the consistent pattern of changes strongly suggests a connection between protein diets and alterations in the gut microbiome.
The research, supported by the UIC Hampton-Marcell lab startup fund, was presented at ASM Microbe 2024 in Atlanta, Georgia, on June 15, 2024.
