Protein-Rich Diet May Alter Gut Microbiome

Switching to a protein-rich diet may lead to changes in the body composition and gut microbiome, according to a study in mice.

Protein, which is made up of 'building blocks' called amino acids, is essential for maintaining muscle and bone health, immune system health, and metabolic reactions. The consumption of protein can also support fat loss while maintaining muscle mass.

A new study led by scientists from the University of Illinois Chicago and presented at ASM Microbe found that switching to a protein-rich diet resulted in significant weight loss, reduced body fat, and induced immediate changes to the gut microbiome in mice.


"These findings provide a crucial foundation for understanding how protein diets influence the gut microbiome and open doors for further investigations into the role of diet in promoting a healthy gut and overall health," Samson Adejumo, a doctoral candidate in biology at the University of Illinois Chicago, said in a statement.

Researchers conducted a four-week experiment with 16 mice. The mice were initially given a standard chow diet for two weeks, followed by protein-rich diets enriched with either branched-chain or aromatic amino acids for the subsequent two weeks.

The research team collected daily fecal samples and weekly body composition measurements to monitor changes in fat and fat-free mass. DNA was extracted from the feces, and sequencing was performed to analyze microbial composition and dynamics over the study period.

A comparison of microbial composition across the four protein groups revealed significant changes in the microbiome following protein enrichment. Gut bacteria responded differently to dietary changes, including to different amino acid groups.

The most substantial microbiome changes occurred in the group fed branched-chain amino acids. These are essential found in meat, dairy, and legumes.

Meanwhile, aromatic amino-acid-rich proteins were associated with greater weight and fat mass loss compared to standard protein and branched-chain amino-acid-rich proteins.

In animals and humans, aromatic amino acids play a major role in synthesizing many biologically and neurologically active compounds essential for maintaining normal biological functions. They are found in meat, poultry, and seafood.

The researchers say it is too early to conclusively state that protein diets caused all observed changes in body composition and gut bacteria. Since the study was conducted in animal models, the results of switching to a protein-rich diet may differ in humans.


The gut microbiome is the ecosystem of about 100 trillion bacteria, viruses, and fungi that help break down certain food components and support the immune and nervous systems.

The disbalance of the gut microbiome is linked to conditions like inflammatory bowel disease, irritable bowel syndrome, obesity, and cancer. Scientists are also looking into the relationship between gut microbes and mental health conditions.

Regardless of what changes protein induces in the microbiome, it remains an essential part of a human diet.


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