The composition of the gut microbiome is essential for overall health and effective weight management. A new study in mice suggests that protein-rich diets can influence gut bacteria and their byproducts, potentially affecting body weight and composition.
The gut microbiome is a complex community of microorganisms in our digestive system that affects nearly every aspect of our health, from digestion and immune function to metabolic processes and body weight. As diet plays a significant role in shaping the composition and diversity of gut microorganisms, it has become increasingly important to understand how our food choices impact our gut’s ecosystem.
Impact of protein-rich diets
Western cultures are increasingly adopting high-protein diets, potentially driven by a growing body of research supporting high-protein diets for weight management. This trend has led researchers at the University of Illinois Chicago to investigate the impact of protein diets on gut microbiome diversity and body composition in a recent mouse study.
The study abstract was presented at ASM Microbe 2024, the American Society for Microbiology’s annual meeting, on June 15 in Atlanta, Georgia. The study also explored how protein fermented by gut bacteria in the colon can produce both beneficial metabolites, such as short-chain fatty acids, and harmful ones, like ammonia and sulfides, which are associated with gastrointestinal disorders.
Key findings
The researchers found that shifting from a carbohydrate diet to various protein-rich diets in mice led to significant weight loss, reduced body fat, and rapid changes in gut microbiome composition. Samson Adejumo, a doctoral candidate in biology at the University of Illinois Chicago, led the research.
This short-term experimental study lasted four weeks and included 16 mice. For the first two weeks, the mice were fed a regular carbohydrate diet. The researchers then switched the mice to four distinct protein diet groups for the remainder of the study:
- Standard protein diet
- 10% aromatic amino acid diet
- 10% branched-chain amino acid diet
- 5% aromatic amino acid and 5% branched-chain amino acid diet
The volume of each diet was the same and contained an equal amount of protein. The researchers collected daily fecal samples and took weekly body composition measurements to monitor changes in body fat and muscle mass. They extracted DNA from the fecal samples and analyzed it to observe how the mice’s gut bacteria changed throughout the study.
Machine learning insights
The study found that the gut microbiota responded differently to each type of diet, showing significant changes from the carbohydrate diet to the four different protein diets. Using machine learning, researchers could predict with 97% accuracy which protein diet the mice consumed by looking at their gut bacteria.
Adejumo elaborated on which protein diets specifically resulted in the greatest fat mass and body weight reductions. “A combination of 5% branched-chain amino acid with 5% aromatic amino acids resulted in the lowest body weight, whereas the 10% aromatic amino acid diet had the lowest percentage of fat mass but the highest weight increase,” he said.
Expert opinions
Alyssa Simpson, RDN, CGN, CLT, a registered dietitian, certified gastrointestinal nutritionist, and owner of Nutrition Resolution in Phoenix, Arizona, spoke on the study’s results. “Changes in gut microbiota can significantly influence body composition and weight loss by altering how efficiently calories are extracted from food,” she stated.
She suggested that a higher ratio of certain bacteria may enhance calorie absorption, potentially contributing to weight gain. Additionally, Simpson noted that “certain bacteria produce lipopolysaccharides that may promote inflammation and fat accumulation, whereas beneficial bacteria may contribute to maintaining gut barrier integrity and regulating appetite through hormone and neurotransmitter production.”
Future directions
Adejumo said, as a next step, “we plan to do some functional analysis and perform some mechanistic experiments to be able to improve overall health.” He added, “We also intend to formulate our diets with single amino acids to fully understand the effect of individual amino acids on diet and identify specific gut microbial strains involved in protein fermentation.”
While more research is needed and animal studies don’t directly translate to humans, learning how dietary protein fermentation affects gut bacteria could help inform the creation of personalized diets that modify the gut microbiome to promote better health and weight management outcomes.
“This concept of personalized nutrition holds promise for broader integration into healthcare practices, potentially revolutionizing how dietary advice is tailored to optimize health outcomes in diverse populations,” Simpson concluded.
