Expectations May Play a Role in Gluten Sensitivity

You’ve probably heard of the placebo effect, where an optimistic individual’s symptoms improve when given a placebo, like “sugar pills.” Less known is the nocebo effect, which occurs when a person’s condition worsens because of their negative expectations.

According to a study published in The Lancet, the nocebo effect may play a role in gluten sensitivity.

Gluten is a protein naturally found in wheat, barley, and rye. For those diagnosed with celiac disease, avoidance of gluten is imperative because exposure to a small trace can lead to a severe autoimmune response, including chronic diarrhea/constipation, gas, anemia, infertility, osteoporosis, and a host of other symptoms.

According to David Sanders, a gastroenterologist and professor at the University of Sheffield, England, “Celiac disease affects about 1% of the global population, but the majority of cases are unrecognized.”

Less well understood is non-celiac gluten sensitivity, which may produce similar gastrointestinal symptoms. Unlike celiac disease, there is no test for gluten sensitivity, which studies have shown produces a different immune response. As gluten sensitivity is often associated with irritable bowel syndrome (IBS), considered a gut-brain disorder, the gut-brain interaction may also play a role.

To see how the nocebo effect and gut-brain interaction might play a role in non-celiac gluten sensitivity, researchers studied 83 participants — 71 women and 12 men — from England and the Netherlands who did not have celiac disease, wheat allergy, or any other gastrointestinal disease and met other specific criteria.

They first answered questionnaires to determine their GI symptoms after consuming gluten to assess their mental health, including depression and anxiety. Among the participants, 35% met the criteria for IBS.

The participants were then randomly assigned to four cohorts based on the expectation that they would consume gluten-containing or gluten-free bread and whether they were actually given gluten-free or gluten-containing bread.

“We found that the combination of expectancy and actual gluten intake had the largest effect on overall and several individual gastrointestinal symptoms, reflecting a considerable nocebo effect, although an additional effect of gluten could not be ruled out,” was the conclusion stated in the study.

They also noted, “Contrary to our hypothesis, we found that emotional well-being — i.e. anxiety, depression, or somatization — did not affect differences between groups for overall and individual gastrointestinal symptom scores during the test day.”

The researchers acknowledged that some component of the bread other than gluten, such as FODMAPs or specific carbohydrates found in wheat, might be the actual source of the problem for some individuals.

Because gluten-free diets are associated with a higher risk of nutritional deficiencies, avoiding gluten without a medical reason could be damaging to your health. Be sure to properly identify trigger foods before making assumptions.