Undiagnosed nonceliac gluten sensitivity symptomatic with low gluten
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Symptom severity among patients with suspected nonceliac gluten sensitivity increased significantly after consuming small amounts of gluten in a randomized controlled trial.
“Because at present nobody knows how many [self-diagnosed] patients really are affected by [nonceliac gluten sensitivity], we performed a double-blind, placebo-controlled, cross-over, gluten-challenge trial of patients suspected of having [nonceliac gluten sensitivity],” the researchers wrote.
A total of 61 patients (53 females) referred to two Italian centers between October 2012 and November 2013 for suspected nonceliac gluten sensitivity (NCGS) were randomly assigned to receive 4.375-g gluten or rice starch per day via gastrosoluble capsules for 1 week after a 1-week run-in period, and followed by a 1-week washout period and cross-over to the other group.
“Rice starch was chosen as the placebo because it is the most readily absorbable of the complex carbohydrates, and thus less fermentable, in the intestinal tract,” the researchers wrote.
The primary outcome was change in overall intestinal and extraintestinal symptom scores based on daily questionnaires completed over the 5-week study period, and the analysis was performed with a per-protocol approach.
Among the 59 patients who completed the trial (two withdrew due to “intolerable symptoms”), 1 week of gluten consumption increased overall symptom severity compared with 1 week of placebo (P = .034), including abdominal bloating (P = .04), abdominal pain (P = .047), foggy mind (P = .019), depression (P = .02) and aphthous stomatitis (P = .025).
The researchers concluded that “most patients showed approximately equal degrees of overall symptoms with either gluten or placebo, although overall symptoms were worsened significantly by gluten in comparison with placebo. Regarding the identification of the true gluten-sensitive patients, it should be interpreted cautiously because of the lack of a control group of non–gluten-sensitive subjects, and it does not represent crucial evidence in favor of the existence of this new syndrome.”
Daniel A. Leffler
“At first glance this is a positive trial. … But further analysis performed by the investigators reveals a complex story,” Benjamin Lebwohl, MD, from the Celiac Disease Center at Columbia University, and Daniel A. Leffler, MD, MS, from Beth Israel Deaconess Medical Center, wrote in an accompanying editorial.
The trial’s “overall positive result was driven by a minority of patients, whereas the rest had no (or at most a modest) worsening compared with placebo,” they wrote. “These findings can be a Rorschach test of sorts, in which the viewer draws interpretations that are based on his or her prior beliefs about NCGS. … It is therefore not surprising that this trial, like its predecessors, seems only to contribute to the uncertainty about NCGS.” – by Adam Leitenberger
Disclosures: The researchers report no relevant financial disclosures. Leffler reports he has been a consultant for or received research support form Alba Therapeutics, Alvine Pharmaceuticals, NIH, INOVA Diagnostics, Genzyme, Coronado Biosciences, Ironwood Pharmaceuticals, and Glenmark Pharmaceuticals. Lebwohl reports he has received research support from Alvine Pharmaceuticals and the National Center for Advancing Translational Sciences, NIH.