Some individuals believe that gluten can aggravate IBS symptoms, even though they consume proteins from wheat, barley, and rye without experiencing any discomfort.

IBS typically leads to abdominal pain, bloating, diarrhea, and constipation. Although the exact mechanism remains unclear, many affected individuals claim that gluten and its sources, which include wheat, can worsen their symptoms.

To determine the true triggers of these symptoms, Premysl Bercik and his team at McMaster University in Canada enlisted 28 participants with IBS who reported relief on a gluten-free diet.

Participants followed a gluten-free regimen for three weeks and then assessed their symptoms based on a scale from 0 to 500, averaging a score of 183.

They were then randomly given one of three types of cereal bars: one containing wheat, another with gluten alone, and a third that was free of both. The first two bars included a gluten dose similar to that found in four slices of bread, according to Bercik.

Although participants were informed that the bars may worsen their symptoms, they were unaware of the specific ingredients they contained.

After one week, participants rated the severity of their symptoms again and returned to a gluten-free diet for two weeks to reverse the effects of the bars. The experiment was repeated twice, ensuring each participant tried all three types of bars.

Following the exposure to the placebo bar, participants indicated a symptom increase of 50 points. Conversely, 11 participants reported worsening after consuming the wheat bars compared to 10 after the gluten-only bars.

Bercik notes, “All three challenges elicited symptoms in a comparable proportion of patients.”

While gluten and wheat may trigger IBS for some individuals, the findings indicate that others might be experiencing a nocebo effect.

Commentary accompanying the study by Sigrid Elsenbruch from the University of Duisburg-Essen, noted that participants were cautioned that the bars could worsen their symptoms.

Analysis of stool samples revealed that participants often did not adhere to the bar consumption as instructed. This raises the possibility that they may not have ingested sufficient gluten or wheat to specifically impact their IBS symptoms.

Bercik added that the research team is exploring how gluten and wheat might trigger IBS symptoms in some individuals, potentially by altering gut microbiota.