Premysl Bercik, MD, PhD, is a professor in the department of medicine at McMaster University.

Premysl Bercik, MD

Navigating IBS Triggers and Restrictive Diets, with Premysl Bercik, MD, PhD

 management frequently includes lifestyle changes, particularly as it relates to what patients eat. Affected individuals often adopt restrictive diets in an effort to manage their symptoms—frequently eliminating gluten and wheat based on the belief that these ingredients are key triggers.

While gluten-free diets have surged in popularity, especially among IBS patients, scientific evidence supporting their use in this population is limited. Seeking to address this gap in research, Premysl Bercik, MD, PhD, a professor in the department of medicine at McMaster University, and a group of investigators conducted a randomized, double-blind, sham-controlled crossover study of adults who met Rome IV criteria for IBS and had previously self-reported improvement on a gluten-free diet.

“We know that many patients perceive that gluten or wheat are triggering their symptoms. We definitely know from other diseases like celiac disease that this specific protein, gluten, which is found in wheat, can trigger immune reactions in patients who are genetically predisposed,” Bercik explained to 

. “In celiac disease, we really know what the sequence of events is and what can be targeted therapeutically. In IBS, we don't know what the mechanism might be.”

Investigators randomly assigned participants in a 1:1:1:1:1:1 ratio to receive 1 of 6 sequences of wheat, gluten, and sham containing gluten and wheat free flour in 3 periods of 7 days, separated by 14-day washout periods. Among the 28 patients who completed the study, there were no statistically significant differences in the proportion of participants with a worsening of IBS-SSS of ≥ 50 points after wheat (39%; risk difference vs sham, 0.11; 95% CI, –0.16 to 0.35) or gluten (36%, risk difference, 0.07; 95% CI, –0.19 to 0.32) versus sham (29%). Additionally, according to the IBS-SSS, there were no clinical or statistical differences between wheat (median value at end of challenge, 179.5; 95% CI, 116.0 to 215.0), gluten (166.5; 95% CI, 105.0 to 242.0), or sham challenges (166.0; 95% CI, 92.0 to 255.0).

Adverse events were reported in 26 (93%) patients after wheat, 26 (93%) patients after gluten, and 26 (93%) patients after sham. Investigators noted study emergent adverse events were similar between challenges, including 5 (18%) patients after wheat, 5 (18%) patients after gluten, and 7 (25%) patients after sham, with no patients reporting severe adverse events.

“A similar proportion of patients reacted to all 3 challenges, which was a big surprise to us because the patients whom we invited to this study were all patients who felt that avoiding gluten made them feel better, so many or most of these patients had been on a gluten free diet for many years,” Bercik said.

Of note, even after learning that wheat or gluten consumption did not appear to trigger their symptoms, many participants continued to adhere to a gluten-free diet and maintained belief in its efficacy.

“For me, [this] shows that if we do studies like this, or if we implement it in clinical practice, then we have to continue working with the patient. We have to guide them, maybe to reintroduce certain foods back into their diet,” Bercik explained. “They may need psychological support – it's not just enough to tell them that gluten is not doing anything in their case… the beliefs are strong, and we have to take that into account.”

Editors’ note: Bercik reports no relevant disclosures.

Brooks A. Study Finds Gluten, Wheat Safe for Most IBS Patients Despite Self-Perceived Sensitivities. HCPLive. July 22, 2025. Accessed July 29, 2025. 

https://www.hcplive.com/view/study-finds-gluten-wheat-safe-most-ibs-patients-despite-self-perceived-sensitivities

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Bercik reviews study findings suggesting gluten restriction is not necessary for most patients with IBS, citing its apparent lack of impact on symptoms.

Premysl Bercik, MD

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