Study Reveals Why a Plant-Based Protein Diet May Curb Inflammatory Bowel Diseases

The Stony Brook-led research could provide a foundation for a better understanding of protein intake and IBD severity

STONY BROOK, NY, July 1, 2026 - Millions of people in the United States and worldwide suffer from inflammatory bowel diseases (IBD). While high consumption of red meat is associated with higher incidences and relapses for IBD patients, understanding the reasons why has not been clear. A new study published in the journal Cellular and Molecular Gastroenterology and Hepatology unravels how dietary protein sources mediate colitis (a form of IBD) pathogenesis. The findings point toward a heightened importance of specific plant-based protein sources over meat for IBD patient consumption.

Led by David C. Montrose, PhD, Assistant Professor in the Department of Pathology in the Renaissance School of Medicine (RSOM) at Stony Brook University, in collaboration with a national team of scientists, the study used numerous murine models of colitis to test the impact of multiple protein isolate sources on disease severity.

This fluorescent staining of a mouse colon identifies bacteria present in the lumen after feeding a beef protein diet. The small, orange-colored structures (top part of picture) mark bacteria accumulating next to the mucus layer (unstained region) above the colon tissue (bottom part).
Credit: David C. Montrose

Montrose says that plant-based diets are believed to be beneficial for IBD patients. However, the components of these diets that underly differential effects on patients, and associated mechanisms involved, remain poorly understood.

The researchers demonstrated in this work that feeding beef-derived protein resulted in the most severe colitis in mice, while a pea protein-containing diet markedly attenuated colonic inflammation.

They found that the colitis-promoting effects of the beef protein were microbially mediated as determined by bacterial elimination or depletion. In the absence of colitis, consumption of beef protein reduced abundance of Lactobacillus johnsonii and Turicibacter sanguinis (gut microbes that support gastrointestinal health) and expanded Akkermansia muciniphila, which resulted in decreased thickness and quality of the mucus that lines the colon. Beef-fed mice also had imbalanced ratios of different types of fecal bile acids. They additionally discovered that dietary psyllium (a form of fiber) protected against beef protein-mediated inflammation and restored bile acid ratios.

"The observed differences in colitis severity in these models were mechanistically linked to diet-mediated alterations in microbial populations and metabolism of bile acids, effects that could be prevented by modifying dietary fiber types," explains Montrose.

He and his co-authors believe that, collectively, the research represents a highly clinically relevant series of findings that provide deep insights into the dietary factors that influence IBD.

"This work helps to lay a foundation for conducting clinical trials to assess the impact of dietary protein sources on disease severity in patients with IBD," adds Montrose.

The research was supported in part by funding from the Crohn's & Colitis Foundation, the National Institutes of Health's National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the American Pulse Association, the Stony Brook Cancer Center and the Bahl Center for Metabolomics and Imaging at Stony Brook Medicine.