AbstractObjectiveTo evaluate the relation between intake of ultra-processed food and risk of inflammatory bowel disease (IBD).DesignProspective cohort study.Setting21 low, middle, and high income countries across seven geographical regions (Europe and North America, South America, Africa, Middle East, south Asia, South East Asia, and China).Participants116 087 adults aged 35-70 years with at least one cycle of follow-up and complete baseline food frequency questionnaire (FFQ) data (country specific validated FFQs were used to document baseline dietary intake). Participants were followed prospectively at least every three years.Main outcome measuresThe main outcome was development of IBD, including Crohn’s disease or ulcerative colitis. Associations between ultra-processed food intake and risk of IBD were assessed using Cox proportional hazard multivariable models. Results are presented as hazard ratios with 95% confidence intervals.ResultsParticipants were enrolled in the study between 2003 and 2016. During the median follow-up of 9.7 years (interquartile range 8.9-11.2 years), 467 participants developed incident IBD (90 with Crohn’s disease and 377 with ulcerative colitis). After adjustment for potential confounding factors, higher intake of ultra-processed food was associated with a higher risk of incident IBD (hazard ratio 1.82, 95% confidence interval 1.22 to 2.72 for ≥5 servings/day and 1.67, 1.18 to 2.37 for 1-4 servings/day compared with <1 serving/day, P=0.006 for trend). Different subgroups of ultra-processed food, including soft drinks, refined sweetened foods, salty snacks, and processed meat, each were associated with higher hazard ratios for IBD. Results were consistent for Crohn’s disease and ulcerative colitis with low heterogeneity. Intakes of white meat, red meat, dairy, starch, and fruit, vegetables, and legumes were not associated with incident IBD.ConclusionsHigher intake of ultra-processed food was positively associated with risk of IBD. Further studies are needed to identify the contributory factors within ultra-processed foods.Study registrationClinicalTrials.gov NCT03225586.