Research uncovers how vegan, vegetarian, and omnivore diets shape the gut microbiome across a global cohort

A study published in Nature Microbiology has unveiled the intricate relationship between dietary patterns and gut microbiome composition. Led by researchers from the University of Trento in Italy and ZOE in the UK, the study brought together expertise from institutions including King’s College London and the European Institute of Oncology in Milan.

The team, co-led by Nicola Segata, Francesco Asnicar, Sarah E. Berry, and Tim D. Spector, analyzed data from over 21,500 individuals spanning five multinational cohorts. The research provided new insights into how vegan, vegetarian, and omnivore diets influence microbial diversity and health outcomes.

Distinct gut microbial signatures were identified for each diet. Omnivores were characterized by species such as Ruminococcus torques and Alistipes putredinis, linked to red meat consumption and negatively correlated with cardiometabolic health. Vegan diets, on the other hand, were associated with beneficial microbes like Lachnospiraceae and Roseburia hominis, which support gut health and anti-inflammatory processes through fiber fermentation. Vegetarians exhibited a unique profile, heavily influenced by dairy consumption, with species like Streptococcus thermophilus predominantly present in their microbiomes.

Dietary patterns were shown to significantly affect microbiome diversity. Omnivores had the highest overall richness, while vegans and vegetarians displayed more specialized gut microbial communities aligned with plant-based food consumption. Importantly, omnivores who consumed more plant-based foods shared beneficial microbial traits with vegetarians and vegans, emphasizing the impact of dietary diversity.

"This study reinforces the profound impact of dietary choices on gut health and overall well-being," noted Segata, Professor of Computational Biology at the University of Trento. The findings underscore how dietary patterns not only influence health but also have far-reaching environmental implications. Diets high in animal products contribute disproportionately to greenhouse gas emissions and resource use, making the shift toward plant-based eating a key strategy for sustainability.

The large-scale approach of this study sets it apart. Using metagenomic sequencing and machine learning, the team identified microbial species linked to specific diets with an impressive accuracy (mean AUC of 0.85). The findings provide a foundation for future nutritional interventions and epidemiological studies, helping refine dietary recommendations for improved health outcomes.

While the research strengthens the case for plant-based diets, the authors caution against oversimplifying the results. They call for additional studies to explore the long-term effects of dietary patterns, particularly the role of specific microbial strains in health and disease.

The study represents a collaborative effort across disciplines and geographies. ZOE, co-founded by Tim Spector, provided detailed dietary data from its PREDICT program, while the University of Trento led the computational analysis. King’s College London contributed expertise in nutritional sciences, and the European Institute of Oncology lent insights into health impacts.

The paper concludes with a call to action for policymakers and healthcare providers to consider these findings when designing strategies for public health and sustainability. By promoting diets rich in plant-based foods, the researchers argue, it may be possible to improve both individual health and the planet's resilience.