Vegans Found to Have Less Diverse Gut Microbiomes Than Omnivores
22:54 31 October, 2026Vegans have, on average, lower gut bacterial diversity than people who eat meat and other animal products. However, their microbiomes also have several potentially beneficial characteristics, while their blood glucose, cholesterol and inflammation levels are lower. These are the findings of researchers at the University of Copenhagen, who studied the gut microbiota of 150 residents of Denmark.
The findings were published in the journal Microbiome. The study included 75 vegans and 75 omnivores. The researchers analyzed stool, blood and urine samples, examining the composition of gut bacteria and viruses, as well as signaling molecules in the body.
The scientists had expected vegans to have more diverse microbiomes because of their higher intake of fiber and other plant compounds. However, the results were unexpected. On average, participants following a plant-based diet had lower gut bacterial diversity.
Professor Oluf Borbye Pedersen of the Novo Nordisk Foundation Center for Basic Metabolic Research suggested that differences in protein intake could be one possible explanation. Protein accounted for approximately 12% of dietary energy among vegans, compared with 17% among participants who consumed animal products. However, vegans with higher protein intake had gut bacterial diversity comparable to that of the omnivorous group.
Despite their lower bacterial diversity, vegans' microbiomes had other characteristics that the researchers consider potentially beneficial to health. They had higher levels of certain bacteria capable of breaking down dietary fiber. The microorganism Blastocystis, previously associated with lower blood pressure, was also more commonly detected among vegans. In addition, vegans had lower average blood glucose and cholesterol levels and fewer markers of inflammation.
Compared with participants who included animal products in their diets, vegans consumed more carbohydrates and fiber but less protein and fat.
The authors emphasize that the study was relatively small and observational. It identifies associations but does not prove that protein intake determines gut microbiome diversity or that switching to a particular diet directly causes changes in health markers.
Therefore, the researchers do not recommend changing dietary habits based on these findings alone. They simply highlight the importance of a balanced diet regardless of dietary choices. Vegans should pay particular attention to consuming enough protein, which can be obtained from legumes, lentils, hemp and chia seeds, quinoa, almonds and other nuts.