This study will assess dynamic effects of two major antigens on the duodenal mucosa by confocal laser endomicroscopy (CLE). Patients will be blinded to the antigens used (wheat, yeast). Following CLE it is planned to have a cross over exclusion diet with/without the antigens including a washout phase. Furthermore, patients will undergo a 2 week FODMAP diet to be able to compare results found of both diets and allow to understand whether our findings of food intolerance will be better and more precise than a common FODMAP diet.