A study in the journal BMC Medicine may shed light on why people who test negative for celiac disease see their symptoms subside when they avoid gluten.

“For the first time, we have scientific evidence that indeed, gluten sensitivity not only exists, but is very different from celiac disease,” says lead author Alessio Fasano, medical director of the University of Maryland’s Center for Celiac Research.

Divergence of gut permeability and mucosal immune gene expression in two gluten-associated conditions: celiac disease and gluten sensitivity

Anna Sapone et al

BMC Medicine 2011, 9:23 doi:10.1186/1741-7015-9-23

Abstract

Background

Celiac disease (CD) is an autoimmune enteropathy triggered by the ingestion of gluten. Gluten-sensitive individuals (GS) cannot tolerate gluten and may develop gastrointestinal symptoms similar to those in CD, but the overall clinical picture is generally less severe and is not accompanied by the concurrence of tissue transglutaminase autoantibodies or autoimmune comorbidities. By studying and comparing mucosal expression of genes associated with intestinal barrier function, as well as innate and adaptive immunity in CD compared with GS, we sought to better understand the similarities and differences between these two gluten-associated disorders.

Methods

CD, GS and healthy, gluten-tolerant individuals were enrolled in this study. Intestinal permeability was evaluated using a lactulose and mannitol probe, and mucosal biopsy specimens were collected to study the expression of genes involved in barrier function and immunity.

Results

Unlike CD, GS is not associated with increased intestinal permeability. In fact, this was significantly reduced in GS compared with controls (P = 0.0308), paralleled by significantly increased expression of claudin (CLDN) 4 (P = 0.0286). Relative to controls, adaptive immunity markers interleukin (IL)-6 (P = 0.0124) and IL-21 (P = 0.0572) were expressed at higher levels in CD but not in GS, while expression of the innate immunity marker Toll-like receptor (TLR) 2 was increased in GS but not in CD (P = 0.0295). Finally, expression of the T-regulatory cell marker FOXP3 was significantly reduced in GS relative to controls (P = 0.0325) and CD patients (P = 0.0293).

Conclusions

This study shows that the two gluten-associated disorders, CD and GS, are different clinical entities, and it contributes to the characterization of GS as a condition associated with prevalent gluten-induced activation of innate, rather than adaptive, immune responses in the absence of detectable changes in mucosal barrier function.

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This randomized controlled trial examines the effectiveness of increasing the dietary content of soluble fiber (psyllium) or insoluble fiber (bran) in patients with IBS. 275 patients aged 18-65 years received 12 weeks of treatment with either 10 grams of psyllium, 10 grams of bran, or 10 grams of a placebo (rice flour). Symptom severity decreased the most in the psyllium group (by 90 points), compared with the placebo group (49 points) and the bran group (58 points) after three months. Results indicate that bran worsens symptoms of irritable bowel syndrome while psyllium offers benefits.

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There is a growing body of evidence to suggest that dietary constituents at least exacerbate symptoms and perhaps contribute to the development of the irritable bowel syndrome (IBS). While the evidence suggests that true food allergies are relatively uncommon, less clearly defined food intolerances may be an important contributor to symptoms in IBS patients. This article reviews the literature supporting a causal link between food and the symptoms of IBS as well as the evidence supporting dietary interventions as a way of managing IBS symptoms.

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Eight clinical trials were reviewed for effectiveness and disturbance of melatonin in IBS and other GI disorders. The results showed disturbances in melatonin concentration in patients with IBS and significant benefits of melatonin in these patients by decreasing abdominal pain and improvement of overall IBS symptom scores. The results of seventeen non-clinical studies showed anti-anxiety, anti-inflammatory, anti-oxidative and motility regulatory effects of melatonin on the GI tract. Melatonin is a target of interest in IBS because of its potentials to regulate GI motility.