A recent study published in Cellular and Molecular Gastroenterology and Hepatology in August 2026 suggests that some plant-based foods, typically considered healthy, may worsen inflammation in individuals with inflammatory bowel disease (IBD). IBD, which includes conditions like Crohn's disease and ulcerative colitis, affects more than 300,000 people in France. These conditions cause chronic inflammation in the digestive tract, and managing flare-ups often involves dietary adjustments. The study highlights that oxalate, a naturally occurring compound found in many plants, may accumulate in the intestines of some IBD patients, potentially worsening their symptoms. Researchers from the University of North Carolina discovered that two proteins responsible for transporting oxalate—SLC26A2 and SLC26A3—were less abundant in the intestinal tissues of individuals with Crohn's disease or ulcerative colitis. A third protein, SLC26A6, was also found to be under-expressed in patients with a specific form of Crohn's disease known as stenosing Crohn’s, which can lead to intestinal narrowing. In mice, diets high in oxalate were shown to accelerate and intensify colitis. In one experiment, a high-oxalate diet reduced survival rates by 60% in mice with chemically induced colitis. In laboratory settings, oxalate was also found to increase the inflammatory response of immune cells. Patients with Crohn's disease were found to have higher levels of oxalate in their stools compared to individuals without IBD, despite both groups consuming similar amounts of plant-based foods. This suggests that differences in how the intestines process oxalate, rather than just dietary intake, may play a role in IBD symptoms. Oxalate is present in many plant-based foods, with higher concentrations found in foods like spinach, rhubarb, beets, sweet potatoes, almonds, cashews, dark chocolate, black tea, and wheat bran. The amount of oxalate can vary based on the specific food item, portion size, and how it is prepared. While some studies link high consumption of ultra-processed foods with an increased risk of IBD, the connection between these foods and flare-ups in already ill individuals is less clear. However, a 2025 randomized trial published in the European Journal of Clinical Investigation found that an elimination diet—restricting red and processed meats, industrial products, sugary drinks, and certain additives—was more effective in achieving clinical remission in adults with mild to moderate Crohn's disease compared to a Mediterranean diet. The study reported remission rates of 70.8% versus 38.1% after 12 weeks. The 2025 European Consensus on IBD (ECCO) does not recommend a one-size-fits-all list of foods to avoid for all patients. Instead, dietary choices should be personalized based on the type of IBD, its current activity level, symptoms, risk of nutrient deficiencies, and individual tolerance. Until more specific guidelines are available, the best course of action for IBD patients is to consult a gastroenterologist or a dietitian specializing in IBD to develop a tailored eating plan.