A new study led by the University of Trento examines the effects of vegan, vegetarian and omnivorous diets on gut microbiomes, revealing critical insights into how food diversity and quality can enhance gut health.
A new study led by researchers from the University of Trento has unveiled the significant influence that diet has on the gut microbiome. By analyzing biological samples from over 21,000 individuals in the United States, the UKand Italy, the research provides compelling evidence that eating habits shape gut health in profound ways.
The study, published in Nature Microbiology, investigates how different dietary patterns — vegan, vegetarian and omnivorous — impact the composition of gut bacteria, which play a crucial role in digestion, immune response and overall health.
“As more and more people adopt vegan and vegetarian diets, we wanted to find out how different their microbiomes are and which microorganisms are responsible for these differences,” first author Gloria Fackelmann, a researcher at the University of Trento’s Cibio Department, said in a news release.
Key Findings: Influence of Diet on Gut Microbiome
One of the study’s essential takeaways is that vegans tend to have the healthiest diets, followed by vegetarians and omnivores. But the most intriguing findings emerged when analyzing the diversity of gut microbiota. According to the researchers, although omnivores showed greater bacterial diversity, vegans and vegetarians had a higher prevalence of beneficial bacteria involved in fiber fermentation.
The scientists found that omnivores have elevated levels of bacteria linked to the digestion of meat, such as Alistipes putredinis and Ruminococcus torques, which are also associated with inflammatory bowel disease and colon cancer.
Conversely, the microbiomes of vegans were rich in bacteria from the Bacteroides and Firmicutes phyla, known for producing short-chain fatty acids like butyrate. These compounds play a vital role in reducing inflammation and supporting metabolic and immune functions.
In an interesting note, the key difference between vegetarians and vegans was the presence of Streptococcus thermophilus, a bacterium predominantly found in dairy products like yogurt and generally more prevalent in vegetarians.
Implications for Dietary Recommendations
The research highlights that the quality of the diet — rather than the dietary pattern itself — dramatically influences the gut microbiome’s composition. Healthier dietary patterns across the spectrum of vegans, vegetarians and omnivores showed a favorable microbiome composition.
This suggests that increasing the intake of plant-based foods while reducing the consumption of processed and animal-based foods can be beneficial to gut health.
Nicola Segata, a professor of genetics and the head of the Computational Metagenomics Laboratory at the University of Trento’s Cibio Department who led the research, emphasized the importance of food variety for a healthy microbiome.
“We have observed that the quantity and diversity of plant-based foods have a very positive impact on the microbiome,” she said in the news release. “Avoiding meat or dairy products does not necessarily have a positive effect if it does not come with a variety of quality plant-based products. From the point of view of the microbiome, what we can generally recommend is that it is important to eat many plant-based foods, especially those rich in fiber. And that food diversity is important.”
The study is part of a larger project aimed at identifying diet benefits based on individual microbiomes, especially concerning cardiometabolic health — ushering in the era of precision nutrition.