 The investigators hypothesized that increased duodenal bile acid exposure or a change in the composition of bile acids lead to impaired duodenal mucosal integrity in FD, allowing luminal substances to pass through the mucosa and result in immune responses and finally in dyspeptic symptom generation. The general aim of this project is to assess if FD patients display increased endogenous duodenal bile acid exposure and a different bile acid composition. In addition, it will be tested whether duodenal mucosal permeability of FD patients with an endogenous duodenal bile acid exposure above the normal range and an altered bile acid composition is higher than in FD patients with a normal endogenous duodenal acid exposure and composition. 