While many individuals report feeling better on a gluten-free diet even when celiac disease has been ruled out, there has been little research into gluten as a trigger for non-celiac digestive issues, according to researchers in Australia. The group set out to change that, publishing a study in the American Journal of Gastroenterology on Jan. 11, 2011, that documented evidence of “non-celiac gluten intolerance.”

The study examined 34 patients with irritable bowel syndrome who followed a gluten-free diet. Of the participants, 56% had human leukocyte antigen (HLA)-DQ2 and/or HLA-DQ8, but celiac disease was ruled out in all cases. Participants were given either gluten or a placebo in the form of two slices of bread and a muffin each day for up to 6 weeks. Remaining food intake followed the gluten-free diet.

Of the 19 patients given gluten, 13 reported that symptoms were “not adequately controlled” after the gluten challenge, according to the study. Of the 15 who took a placebo, only 6 reported such a change in symptoms. Participants who ingested gluten showed a worsening in overall symptoms, pain, bloating, satisfaction with stool consistency, and tiredness, according to the study. However, there were no changes in antibody levels or intestinal permeability, regardless of whether the participant had DQ2/DQ8 or not, the researchers noted.

“’Non-celiac gluten intolerance’ may exist, but no clues to the mechanism were elucidated,” they concluded.