Recently, a group of medical researchers in Australia (Biesiekierski et al) performed a double-blind study on the effects of gluten on gastrointestinal symptoms. The stated aim of the study was to determine whether gluten is the trigger for symptoms in non-celiac individuals. (Celiac disease is a condition that damages the small intestine lining, preventing it from absorbing important nutrients.) Jessica R. Biesiekierski and her colleagues at the Monash University Department of Medicine wanted to determine to what extent people without this condition are affected by eating gluten. Their secondary inquiry was into the mechanism: if gluten caused these symptoms, exactly how did it do so?


The Starting Point


The researchers began with this premise: Even though gluten-free diets were being prescribed widely—and successfully—for patients with gastrointestinal symptoms, there was a lack of conclusive scientific evidence that gluten was indeed the trigger for these symptoms. They set out to determine in a scientific fashion whether gluten is, in fact, a trigger for gastrointestinal symptoms for those not suffering from celiac disease.


The Process and Results


The researchers chose a number of irritable bowel patients whose symptoms were under control and who were already on gluten-controlled diets. They then divided them into experimental and control groups. Those in the experimental group received gluten, while the others received placebos in the form of two slices of bread and one muffin per day (none of the participants knew whether they were eating gluten or not). The researchers then compared symptoms of the two groups, looking for evidence of intestinal inflammation, injury, and activation of the immune system.


The results were quite interesting. Of the 19 patients (68 %) in the gluten group, 13 reported that their symptoms were not adequately controlled, while 6 of 15 (40 %) on placebo reported no change in symptoms. On a visual scale, patients who received gluten had significantly worse overall symptoms within one week. These included pain, bloating, unsatisfactory bowel movements, and fatigue. No significant changes were found, however, in levels of celiac (intestinal lining) antibodies, celiac permeability (the ability of nutrients to penetrate the intestine), or C-Reactive proteins.


Conclusion and Implications


The researchers’ conclusion was as follows: “Non-celiac gluten intolerance may exist, but no clues to the mechanism were elucidated.” * In other words, gluten intake seemed to take its toll on a majority of the IBS patients studied, but the study failed to show exactly how that happened. This study is significant, however, because it provides—for the first time—highly reliable evidence that gluten itself may trigger gastrointestinal symptoms in patients not suffering from celiac disease.


What are the implications of this study for irritable bowel patients whose symptoms are controlled by gluten-free diets? They should definitely continue restricting their gluten intake. It’s true that not all the facts on how gluten affects the gastrointestinal system are in yet. However, this does not mean patients should go back to gluten-rich diets! There is significant evidence that gluten does indeed cause gastrointestinal upset. Nine participants dropped out of the study before it was over due to intolerable symptoms! Those of you who have found your symptoms well-controlled on gluten-free diets will be well-served to remain on them. It will be interesting to see what new information future studies provide about precisely how gluten causes abdominal pain, bloating, and fatigue. In the meantime, by all means stay on your gluten-free diets to remain as symptom-free as possible!




* Biesiekierski et al, Gluten Causes Gastrointestinal Symptoms in Subjects without Celiac Disease: A Double-Blind Randomized Placebo-Controlled Trial. Monash University Department of Medicine and Gastroenterology, Box Hill Hospital, Box Hill, Victoria, Australia, 2011.