Identification of Gluten Sensitivity in Irritable Bowel Syndrome (IBS-NCGS)

Double Blind Randomized Clinical Trial in Subjects With Irritable Bowel Syndrome for the Identification of Gluten Sensitivity

The aim of our study will be to establish in how many subjects with gastrointestinal symptoms and previous diagnosis of irritable bowel syndrome (IBS), the clinical picture is attributable to non celiac gluten sensitivity (NCGS) or fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAPs) intolerance. For this purpose, all subjects with IBS will take a low FODMAPs diet, which implies the absence of cereals and consequently of gluten, and those presenting symptom improvement during this dietary treatment, will be exposed to a double-blind gluten or placebo challenge, to make a diagnosis of NCGS.

Study design: For this study, patients with diagnosis of IBS performed by Rome IV criteria and followed as outpatients at the Clinical Nutrition Clinic of "Petrucciani" Nursing Home of Lecce (LE), Italy, will be enrolled. At baseline, the enrolled subjects will follow a balanced normal-caloric low-FODMAP and gluten-free diet for a period of 4 weeks. At the end of the 4 weeks patients who did not experience an improvement in symptoms will be considered "non-responders" and discontinue the clinical trial. Only those subjects who had showed a significant improvement in symptoms, will be enrolled for the phase 2 of the study that includes a challenge with gluten or with placebo, as described by the Salerno criteria.

gluten will be added for 7 days to the low FODMAP/gluten free diet diet. After 1 week of wash-out, patients will switch (cross-over) to placebo for another 7 days

Placebo will be added for 7 days to the low FODMAP/gluten free diet diet. After 1 week of wash-out, patients will switch (cross-over) to gluten for another 7 days

To evaluate the FODMAP intolerance, the response to a low FODMAP diet will be assessed by a visual analogue scale (VAS) before and after the dietary challenge. The VAS scale consists in is a straight horizontal line of fixed length, usually 100 mm. The ends are defined as the extreme limits of the parameter to be measured (symptoms, pain, subjective feeling of well-being/malaise) orientated from the left (worst) to the right (best) The patient is invited to indicate a position (a point) along the line.

To evaluate the NCGS, the response to the gluten challenge will be assessed by a visual analogue scale (VAS) before and after the dietary challenge. The VAS scale consists in is a straight horizontal line of fixed length, usually 100 mm. The ends are defined as the extreme limits of the parameter to be measured (symptoms, pain, subjective feeling of well-being/malaise) orientated from the left (worst) to the right (best) The patient is invited to indicate a position (a point) along the line.

Inclusion Criteria: a gluten-containing diet for at least six months before enrollment anti-transglutaminase antibodies (IgA and IgG) absence normal serum IgA levels prick and specific IgE tests for wheat allergy negative Exclusion Criteria: celiac disease wheat allergy chronic intestinal inflammatory diseases psychiatric disorders major abdominal surgery (in particular intestinal resections) diabetes mellitus previous anaphylactic episodes gluten-free diet in the previous six months pregnant or lactating women.

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