Vegan diets have a surprising effect on gut bacteria, study reveals

Key Points:

• A Danish study of 150 healthy adults found that vegans had less diverse gut bacteria than meat-eaters, despite consuming nearly 70% more fiber, challenging the assumption that plant-based diets always promote greater gut microbial diversity.
• Vegans' lower gut bacterial diversity may be linked to their lower protein intake (12% of calories vs. 17% for meat-eaters), with higher protein consumption among vegans associated with increased bacterial variety.
• Although vegans had fewer bacterial species overall, many species more common in vegans were associated with health benefits, and vegans showed favorable metabolic markers such as lower blood sugar, cholesterol, inflammation, and certain harmful gut-derived compounds.
• The study also found differences in gut viruses and the presence of the organism Blastocystis, which was more common in vegans and linked to lower systolic blood pressure, though further research is needed to confirm these findings.
• Limitations include the study’s observational design, small and geographically limited sample, and single-time measurements; researchers emphasize the need for more studies to understand how vegan diets impact gut microbiota and long-term health.