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Association Between Ultra-Processed Foods and Clinical Relapse in Crohn's Disease: A Systematic Review and
Sunil Samnani1, Hiu-Ki Rachel Tran2, Kathy Vagianos3
1Gastroenterology Fellow, Department of Medicine (Division of Gastroenterology) and Farncombe Family Digestive Health Research Institute; McMaster University, Hamilton ON, Canada.
Background:
Higher consumption of ultra-processed foods (UPFs) has been linked to an increased risk of developing Crohn's Disease (CD) and is hypothesized to worsen activity of CD through mechanisms such as gut microbiome alterations and increased intestinal permeability.
Objective:
To assess the association between dietary intake of UPFs and clinical relapse in patients with CD.
Methods:
A comprehensive search of MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials from database inception to March 18, 2025. At the time of the search, records in the Cochrane Central Register of Controlled Trials were available through February 28, 2025. The study included prospective cohort studies and randomized controlled trials enrolling adults with CD in clinical remission, comparing higher versus lower UPF intake or no UPF, with a minimum follow-up of 6 months. Studies not meeting these criteria, including retrospective designs and non-English publications, were excluded. The primary outcome was clinical relapse within one year. Study quality was assessed using the Newcastle-Ottawa Scale, and overall certainty of evidence was evaluated using the GRADE framework. Pooled odd ratios (ORs) and 95% confidence intervals (CIs) were calculated using DerSimonian-Laird random-effects meta-analysis based on estimates and standard errors. Heterogeneity was assessed using the I2 statistic. The publication bias was planned to assess using funnel plots and statistical tests if sufficient studies were available.
Results:
1945 studies were identified through the search. After removing duplicates, and abstract screening, 13 studies were selected for full-text review and 3 prospective cohort studies involving 276 patients with CD were included in the analysis. Pooled analysis demonstrated a significant association between UPF intake and relapse in patients with CD. Patients with higher versus lower UPF intake had increased odds for clinical relapse (OR 2.27, 95% CI 1.01-5.13, p = 0.048; I2 = 20.95%), although the certainty of the evidence was rated as very low according to the GRADE framework.
Conclusion:
This study suggests that higher UPF intake is associated with increased odds of clinical relapse in patients with Crohn's disease in remission. However, the certainty of evidence is very low, and additional well-designed prospective studies and randomized trials are required before firm dietary recommendations can be made.
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