The team from the University of Trento (Italy) engaged 21,561 volunteers in their research. This robust sample size allowed scientists to explore the connection between diet and gut microbiome health.
Researchers also discovered that, regardless of the type of diet a person chooses, there is one unifying factor that is crucial for a healthy microbiome. But more on that later.
What Did the Researchers Learn?
During their work, the scientists examined biological samples from this vast group of volunteers, identified key differences in their dietary preferences, and determined how these preferences affect the diversity of gut bacteria.
“Following diets that include or exclude major food groups, such as meat, dairy, fruits, and vegetables, leaves a mark on the gut microbiome. We found significant changes in the microbiomes of vegans, vegetarians, and omnivores, linked to several characteristic microbes,” the researchers stated.
The team learned that while vegans and vegetarians adhered to healthier eating habits, the microbiome of omnivorous participants was more diverse. However, as the researchers noted, different bacteria affect our gut and overall health in various ways, and not all of them are beneficial.
Each dietary system exhibited unique microbial signatures. The gut microbiomes of omnivorous participants contained higher levels of bacteria associated with meat digestion, particularly Alistipes putredinis. However, this increased diversity also indicated the presence of bacteria like Ruminococcus torques and Bilophila wadsworthia, which, according to scientists, are linked to numerous health issues, including inflammatory bowel diseases, heart disease, and certain types of cancer.
The microbiome of vegans featured a wealth of bacteria essential for fiber fermentation; some of these contribute to the production of short-chain fatty acids, such as butyrate. These bacteria help reduce inflammation and promote healthy metabolism and immune system function.
In the microbiome of vegetarians, there was a higher presence of Streptococcus thermophilus, which is associated with dairy products. This bacterium is used in yogurt production and may influence certain toxins in the gut, as reported by ILFScience.
However, while the study examined various dietary preferences, one key finding holds true for all participants: omnivores, vegetarians, and vegans alike. Without a rich intake of plant-based foods, especially those high in fiber, none of them will achieve a healthy diversity in their gut microbiome.
“We noticed that the quantity and variety of plant-based foods have a very positive impact on the microbiome,” noted Professor Nicola Segata, the lead author of the study. “Abandoning meat or dairy products does not necessarily yield positive effects if it is not accompanied by the consumption of a diverse range of quality plant foods,” he added.
The results of the study were published in the journal Nature Microbiology.