You may have been told that unless you have the autoimmune disorder celiac disease, you’re not gluten intolerant, and the pain and bloating you blame on sensitivity to gluten is all in your head. Meanwhile, the gluten-free food industry is booming as never before, and many people are singing the benefits of a gluten-free life. So…is gluten sensitivity real? Or is it just the latest craze?


According to a new study, it is entirely possible to be sensitive to gluten without having a wheat allergy or celiac disease. But it’s also possible that gluten exerts a nocebo effect on some folks. A nocebo effect is an ill effect caused by the suggestion or belief that something—in this case gluten/wheat–is harmful.

The study, conducted by researchers from the Universities of Pavia and Bologna in Italy, involved 59 participants who had self-described gluten intolerance. They reported symptoms such as bloating, gassiness, diarrhea, headache and brain fog. Before starting the study, all of the participants had blood work and biopsies of the small intestine to rule out wheat allergies and celiac disease.

To identify whether gluten was actually causing symptoms, the researchers put participants on a strict gluten-free diet for five weeks, and during part of that time had them take one of two daily pills—either wheat gluten or a placebo. Participants switched off during the study so that everyone had a chance to take gluten pills and placebos during different weeks (but without knowing which was which, of course). Each gluten pill contained about the amount of gluten found in two slices of white bread.

Participants completed daily questionnaires that measured the severity of a wide range of symptoms on a scale of zero (not affected) to three (severely affected). In addition to intestinal symptoms, such as pain, bloating and gas, nonintestinal symptoms frequently associated with gluten intolerance, such as headache, tiredness, malaise, brain fog and anxiety, were also asked about.

The results: The participants’ total average symptom severity score was 30% higher during the week they were given gluten compared with the week they received placebo pills, showing that gluten did make a difference for some. However, when the researchers plotted each participant’s weekly scores on grids to view correlations between how each person felt during gluten and gluten-free weeks, they found that about half of the participants complained about symptoms to the same degree whether they were receiving gluten or not. The remaining participants either logged in more symptoms when they were receiving gluten or placebo. Of the nine patients who recorded more symptoms while on gluten than placebo, three (amounting to 5% of the study group) had scores that consistently showed symptom flares when exposed to gluten but not placebo. Symptoms of bloating, abdominal pain, brain fog, depression and canker sores—the most common intestinal and nonintestinal symptoms experienced across the board—were consistently and significantly worse during the week of gluten exposure in these patients compared with the rest of the study group. The researchers commented that these participants likely had true gluten intolerance despite lack of wheat allergy or celiac disease and that the other six participants may have had a lesser level of gluten sensitivity. They also point out that the dose of gluten given was low, and so higher amounts might have shown greater sensitivity in more of the participants.


These study findings add weight to both sides of the argument…yes, gluten intolerance does seem to occur in a small percentage of people. On the other hand, gluten may not actually be behind symptoms that many people experience and attribute to gluten intolerance.

If you notice that you have abdominal pain or bloating, fogginess or low mood after eating foods with gluten, you can test whether you are truly sensitive to it by going gluten-free for one or two weeks, evaluating whether symptoms improve and then reintroducing bread or pasta back into your diet and again evaluating symptoms. A better strategy, though, would be to consult a dietitian or naturopathic doctor who can expertly evaluate your symptoms and guide you through a diet regimen to correct the problem without compromising nutrition—whether that means avoiding gluten or following some other strategy.