FRIDAY, July 25, 2025 (HealthDay News) -- Patients with irritable bowel syndrome (IBS) with self-perceived gluten sensitivity react similarly to wheat, gluten, and sham challenges, according to a study published online July 21 in The Lancet Gastroenterology & Hepatology.Caroline Larissa Seiler, Ph.D., from McMaster University in Hamilton, Ontario, Canada, and colleagues conducted a randomized, double-blind, sham-controlled crossover study involving adults who met Rome IV criteria for IBS and had previously self-reported improvement on a gluten-free diet. Eligible participants were randomly assigned to receive one of six sequences of wheat, gluten, and sham (gluten- and wheat-free flour) cereal bars in three periods of seven days separated by a 14-day washout period. Twenty-nine participants were enrolled and randomly assigned; 28 completed the study.The researchers observed no significant differences in the proportion of participants with a worsening of IBS symptoms of at least 50 points on the IBS Symptom Severity Score after wheat or gluten versus sham (39 and 36 percent, respectively, versus 29 percent). Adverse events were reported in 93, 93, and 93 percent of patients after wheat, gluten, and sham, respectively. Between challenges, study-emergent adverse events were similar (18, 18, and 25 percent after wheat, gluten, and sham, respectively). There were no reports of severe adverse events."Not every patient who believes they are reacting to gluten actually does," senior author Premysl Bercik, M.D., also from McMaster University, said in a statement. "Some truly have a sensitivity to this food protein, but for many others, it's the belief itself that's driving their symptoms and subsequent choices to avoid gluten-containing foods."Abstract/Full Text (subscription or payment may be required).Sign up for our weekly HealthDay newsletter