FODMAPS (fructose, oligosaccharides, monosaccharides, disaccharides and polyols) are characterised as fermentable but poorly absorbed carbohydrates which enter the colon and are utilised by colonic bacteria. During fasting colonic nutrients are scarce but ingesting FODMAPS causes a rapid increase in carbohydrate which can overwhelm the microbiota's ability to utilise substrate. The excess reducing equivalents will generate hydrogen or methane. The principal symptoms are diarrhoea and abdominal distension. Patients with irritable bowel syndrome appear to benefit by restricting intake, possibly because they are hypersensitive to intestinal distension.

The focus of the study is to evaluate if in celiac patients with persistent abdominal symptoms and with a correct gluten free diet, a low FODMAPs diet can improve their symptoms. Moreover the study would like to observe if a dietary restriction in FODMAPs carries the risk of nutritional inadequacy.

Inclusion Criteria:

• Celiac patients assessed through positive serology and histology
• functional patients according IBS Roma III criteria
• subjects with VAS>5

Exclusion Criteria:

• refractory celiac disease
• disaccharide intolerance (fructose an lactose breath test)
• abdominal surgery
• comorbidity
• patients recruited in other clinical trials
• positive patients at lactulose breath test (SIBO)