Gluten Foods Aren't Causing Your Gut Pain, but Fructan May Be

Onions, not bread, could be the source of your stomach problems. PAUL J. RICHARDS/AFP/Getty Images

As many as 3.1 million Americans are gluten-free because they believe they experience some sort of adverse reaction to eating gluten, ranging from minor stomach bloating to severe diarrhea. New research suggests that, for a fraction of this group, it may be another food property that is at the root of their ailments: fructan.

In a new study published online in Gastroenterology, researchers from Monash University in Australia and University of Oslo in Norway have revealed that fructan, a type of carbohydrate found in wheat and some vegetables, may cause similar symptoms to gluten sensitivities. As a result, some individuals may confuse their fructan problems for gluten sensitivity, and as a result, not properly address and treat their issue.

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For the research, the team had 59 individuals who were already on a self-instituted gluten-free diet, but had been medically excluded from having celiac disease, randomly assigned to eat diets that contained either gluten, fructans, or a placebo. The volunteers did not know which of these diets they were assigned. This was done for a week.

Symptoms were measured using a test called the gastrointestinal symptom rating scale, irritable bowel syndrome (GSRS-IBS), originally designed to note IBS symptoms in patients. Higher scores translate into more severe symptoms. The double-blind crossover challenge allowed the researchers to properly see how each food property affected the volunteers without the risk of human bias.

Results revealed that the overall consumption of fructan was associated with higher scores on the IBS test than both gluten and placebo consumption. For example, out of the study participants, 24 had the highest GSRS-IBS scores after consuming fructan, compared to only 13 with gluten and 22 with the placebo. Personal accounts from volunteers showed that they only reported bloating and stomach pains while eating diets that had fructan, not those with gluten or placebos.

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According to the Tufts Medical Center, fructan is a naturally occurring carbohydrate that is found not only in some breads and barley but also in a number of vegetables such as cabbage and broccoli. However, in the U.S., about 95 percent of fructans consumed are from wheat and onions. The carbohydrate has a history of being linked with stomach woes, and past research has named fructan as a very probable source of irritable bowel symptoms.

These results suggest that fructan, not gluten, may be at the root of your unexplained stomach woes. Although more research will be needed (and individuals should not attempt to self-diagnosis stomach ailments without first consulting a medical professional) the study shows that maybe we've been demonizing the wrong carbohydrate after all.