A large prospective cohort study, the NutriNet-Sante study, found that ultra-processed food consumption was significantly associated with inflammatory bowel disease incidence in adults who were disease-free at baseline. Each 10 percent increment in ultra-processed food in the diet was associated with an 11 percent higher risk of developing IBD. The association was independent of total fibre intake, suggesting that the additives and processing methods in ultra-processed foods, rather than just fibre absence, contribute to disease risk.
The Emulsifier Mechanism
Carboxymethylcellulose and polysorbate-80 are two of the most commonly used food emulsifiers in ultra-processed products. Animal research has found that these emulsifiers at concentrations equivalent to typical dietary exposure penetrate the mucus layer of the colon, allowing bacteria to directly access the epithelial surface and triggering inflammatory responses. Human research using organoid models has replicated this finding. These emulsifiers are found in a wide range of processed sauces, dairy alternatives, dressings, and baked goods.
Diet and IBD Remission
For adults with established IBD, the evidence for specific dietary interventions during remission is growing. The Specific Carbohydrate Diet and the Mediterranean diet have both been tested in clinical trials and found to produce better remission rates and quality of life scores than standard dietary advice. Common principles include avoiding ultra-processed food additives, emphasising whole plant foods during tolerance, prioritising fermented foods including low-FODMAP options during flares, and ensuring adequate vitamin D and zinc status.