Plant and Animal Protein Sources in Inflammatory Bowel Disease: Current Evidence and Clinical Implications

With the consumption of protein consumption increasing globally, there are gaps in our understanding of the differences in protein sources, particularly between animal and plant proteins and their recommendations for patients with Inflammatory Bowel Disease (IBD). This narrative review synthesizes current evidence of how animal and plant proteins differentially exert physiological effects, influence IBD risk, and outcomes. First, protein sources vary in their amino acid profiles, co-existence with other nutrients and consumption within a dietary pattern, factors that influence their physiological effects. Second, observational data showed possible associations between higher intake of animal protein and risk of Ulcerative Colitis (UC); however, this association is less consistent with Crohn's Disease (CD). High intake of meat, specifically red meat, is also associated with a greater risk for a UC relapse. Third, specific animal proteins are utilized as part of efficacious strategies for the induction and maintenance of CD. In conclusion, the available data suggest that recommendations for the IBD patient should move beyond animal versus plant protein advice but consider individual protein sources and the wider dietary pattern.