Role of diet in prevention versus treatment of Crohn's disease and ulcerative colitis.

Diet is a modifiable risk factor for disease course and data over the past decade have emerged to indicate its role in Crohn's disease (CD) and ulcerative colitis (UC). However, literature is riddled with misinterpretation of data, often leading to unexpected or conflicting results. The key understanding is that causative factors in disease development do not always proceed to an opportunity to change disease course, once established. Here, we discuss the data on dietary influences in three distinct disease states for CD and UC-predisease, active disease and quiescent disease. We appraise the literature for how our dietary recommendations should be shaped to prevent disease development and if or how that differs for CD and UC induction therapy and maintenance therapy. In UC, principles of healthy eating are likely to play a role in all states of disease. Conversely, data linking dietary factors to CD prevention and treatment are paradoxical with the highest quality evidence for CD treatment being exclusive enteral nutrition, a lactose, gluten and fibre-free diet comprising solely of ultraprocessed food-all dietary factors that are not associated or inversely associated with CD prevention. High-quality evidence from dietary trials is much awaited to expand our understanding and ultimately lead our dietary recommendations for targeted patient populations.
Competing Interests: Competing interests: EPH has received research grants for investigator-driven studies from Mindset Health Pty Ltd and speaker honoraria from Sandoz Pty Ltd and Mindset Health Pty Ltd; LG received speaker honoraria from Janssen, Takeda, Abbvie, Pfizer, Galapagos, Altman and is involved with studies related to the Mediterranean diet; CSS: Wolfson Medical Center IP for Nestle Health Science, speaking fees from Nestle, Takeda and Ferring, and was involved in the development of the UCED and some studies related to CDED; JV received speaking fees from Janssen, consultancy fees from Ferring; VS was involved in the development of the CD-TREAT diet.
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