Non-absorbable, fermentable residues in the diet increase intestinal gas production and induce gas-related symptoms, such as flatulence, abdominal bloating and distention; however, prebiotics, which are also fermented by colonic bacteria, have been shown to improve this type of symptoms. The aim is to demonstrate whether a prebiotic induces adaptive changes in metabolic activity of gut microbiota and colonic biomass that explain its beneficial effect on gas-related symptoms.

Single-centre, single arm, open label, proof-of-concept study in healthy subjects. The study will consist of a pre-administration phase (2 wk), an administration phase (4 wk) and a post-administration phase (2 wk). A soluble prebiotic fiber (resistant dextrin 14 g/d) will be administered during the 4 wk administration phase. During 4 days immediately before, at the beginning and at the end of the administration phase and at the end of the post-administration phase participants will be put on a standard diet and the following outcomes will be measured: a) number of gas evacuations during daytime for 2 days by means of an event marker; b) volume of gas evacuated via a rectal tube during 4 hours after a test meal, by means of a barostat; c) microbiota composition by fecal analysis.

Inclusion Criteria:

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Exclusion Criteria:

• gastrointestinal symptoms
• recent (3 months) antibiotic intake
• change in dietary habits 4 weeks before