A vegan diet can potentially transform your gut and metabolism, and slash your risk of chronic diseases, according to recent research, with scientists suggesting that swopping meat and dairy can do more than just help animals and the planet.
The study, which analysed data from more than 21 000 participants in the UK, US and Italy, found that a plant-based diet fosters bacteria that improve health and reduce the risk of diseases such as diabetes and heart conditions, reports The Independent.
Published in Nature Microbiology, the research explored the gut microbiomes of vegans, vegetarians, and omnivores, and found that even small dietary changes, like eating more fruits, vegetables and fibre, can result in meaningful health improvements.
The gut microbiome, a complex ecosystem of trillions of microorganisms, is critical for breaking down food, releasing nutrients, and regulating immune responses. But, according to the study, what we eat greatly influences which microbes thrive.
Out of the three groups of people studied, vegans, the study found, had the highest levels of bacteria linked to fibre digestion such as Roseburia hominis and Lachnospiraceae species.
These microbes produce short-chain fatty acids, which play a key role in reducing inflammation, strengthening gut barriers and supporting metabolic health.
Omnivores, on the other hand, harboured bacteria associated with digesting meat such as Ruminococcus torques and Bilophila wadsworthia. These microbes have been linked to higher inflammation and poorer cardiometabolic health outcomes, the study noted.
Vegetarians had microbiomes that fell between these two extremes, the research found, benefiting from their partial intake of plant-based foods.
Diet diversity matters more than we think it does and even a temporary shift can help boost gut health, the researchers said. Omnivores who increased their intake of fruits, vegetables, and whole grains showed significant improvements in gut health, showing that even modest dietary changes could yield benefits.
“This study underscores how important diet is in shaping the gut microbiome and our overall health,” said Professor Tim Spector, study co-author and founder of gut health company ZOE, which was part of the research.
“A plant-rich diet, particularly one high in a variety of fruits and vegetables, leads to a healthier microbiome composition, which is important for better health outcomes in the long run, including a reduced risk of chronic diseases.”
One intriguing finding of the study is that some gut bacteria may come directly from the food we eat.
Vegans were more likely to harbour microbes found in soil such as Enterobacter hormaechei, suggesting that fresh fruits and vegetables could introduce beneficial bacteria into the gut, the study found.
Omnivores and vegetarians had microbes linked to dairy products such as Streptococcus thermophilus, a yogurt and cheese starter culture.
Gut health and chronic disease
The study also highlights the importance of short-chain fatty acids, compounds produced by certain gut bacteria when they digest fibre. These fatty acids have been linked to reduced risk of conditions such as diabetes, cardiovascular disease and even colorectal cancer.
By contrast, diets high in animal products and processed foods tend to favour microbes that produce harmful compounds, such as trimethylamine, which has been associated with heart disease.
Study details
Gut microbiome signatures of vegan, vegetarian and omnivore diets and associated health outcomes across 21 561 individuals
Gloria Fackelmann, Paolo Manghi, Nicola Segata et al.
Published in Nature on 6 January 2025
Abstract
As plant-based diets gain traction, interest in their impacts on the gut microbiome is growing. However, little is known about diet-pattern-specific metagenomic profiles across populations. Here we considered 21 561 individuals spanning five independent, multinational, human cohorts to map how differences in diet pattern (omnivore, vegetarian and vegan) are reflected in gut microbiomes. Microbial profiles distinguished these common diet patterns well (mean AUC = 0.85). Red meat was a strong driver of omnivore microbiomes, with corresponding signature microbes (for example, Ruminococcus torques, Bilophila wadsworthia and Alistipes putredinis) negatively correlated with host cardiometabolic health. Conversely, vegan signature microbes were correlated with favourable cardiometabolic markers and were enriched in omnivores consuming more plant-based foods. Diet-specific gut microbes partially overlapped with food microbiomes, especially with dairy microbes, for example, Streptococcus thermophilus, and typical soil microbes in vegans. The signatures of common western diet patterns can support future nutritional interventions and epidemiology.
The Independent article – Study finds unexpected benefit to plant-based diet (Open access)
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