The food we eat has a profound impact on the bacteria living in our gut, known as the gut microbiome. This community of microorganisms plays a key role in digestion, immune health, and overall well-being.
A recent study, published in Nature Microbiology, explored how different diets—vegan, vegetarian, and omnivorous—affect the microbiome and identified specific microbes linked to better health.
Researchers analyzed data from 21,561 people across the United States, the United Kingdom, and Italy. This large-scale study compared the gut microbiomes of vegans, vegetarians, and omnivores, shedding light on how diet shapes the bacteria in our intestines.
The team, led by scientists at Italy’s University of Trento and King’s College London, discovered that diet patterns influence not only the types of microbes that thrive in the gut but also the microbes introduced directly through food.
Vegans were found to have the healthiest diets overall, followed by vegetarians and omnivores. However, a closer look revealed that it’s not just the diet label that matters—it’s the quality and variety of foods consumed.
Individuals with diets rich in plant-based foods, regardless of being vegan, vegetarian, or omnivorous, had a more favorable microbiome composition.
The researchers found that omnivorous diets had the highest diversity of gut bacteria. However, diversity alone doesn’t always mean a healthier microbiome.
Some bacteria common in omnivores, such as Ruminococcus torques and Bilophila wadsworthia, are linked to inflammatory conditions and a higher risk of colon cancer.
Omnivores also had more bacteria involved in protein fermentation, such as Alistipes putredinis, which are associated with digesting meat.
In contrast, the microbiomes of vegans were rich in bacteria that ferment fiber, particularly species from the Bacteroidesand Firmicutes phyla.
These bacteria produce short-chain fatty acids, such as butyrate, which help reduce inflammation and support metabolic and immune balance. Vegetarians, who include dairy in their diets, had unique bacteria like Streptococcus thermophilus, a microbe found in fermented dairy products like yogurt.
One of the most intriguing findings was how bacteria transfer from food to the microbiome. Vegans had fewer food-associated bacteria in their gut, except for those derived from fruits and vegetables, which were highly present.
In comparison, vegetarians and omnivores had more bacteria linked to dairy products, particularly fermented foods.
The study highlights the importance of diet quality in shaping the microbiome. Researchers observed that people with diets rich in plant-based foods—high in fiber and diverse in variety—had healthier microbiomes.
Avoiding meat or dairy alone doesn’t guarantee better gut health; the key lies in consuming a wide range of high-quality plant-based foods.
Professor Nicola Segata, who led the study, emphasized that food diversity is crucial. He explained that eating more plant-based foods, especially those rich in fiber, positively impacts the microbiome.
However, simply excluding certain food groups, like meat or dairy, without replacing them with nutritious alternatives, may not provide the same benefits.
This research is part of a larger effort to develop “precision nutrition,” which aims to create diet recommendations tailored to an individual’s unique microbiome.
By understanding how different foods influence gut bacteria, scientists hope to improve health outcomes, particularly for conditions like heart disease and diabetes.
The findings reinforce the idea that what we eat profoundly shapes our gut microbiome and, ultimately, our health. A diet rich in diverse, plant-based foods can support a healthier gut, regardless of whether someone follows a vegan, vegetarian, or omnivorous diet.
If you care about gut health, please read studies about how probiotics can protect gut health, and Mycoprotein in diet may reduce risk of bowel cancer and improve gut health.
For more health information, please see recent studies about how food additives could affect gut health, and the best foods for gut health.
The research findings can be found in Nature Microbiology.
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