 Duodenal biopsies were obtained from 25 healthy volunteers HV and 25 FD patients. Biopsies were mounted in Ussing chambers to measure transepithelial resistance TEER and paracellular permeability using fluorescein isothiocyanate dextran FITC-dx4, MW 4kDa. Expression of bile acid-sensing receptors TGR5, VDR, PXR, FXR and CAR in duodenal biopsies was measured by western blot and real time RT-PCR. Immunohistochemistry was used to evaluate eosinophil and mastcell infiltration in duodenal biopsies of FD patients and HV. Duodenal fluid aspirates were collected at fixed time points during 1 hour in fasted state and 1.5 hours after a liquid meal Nutridrink, 200ml. Concentration and composition of the bile salt pool including glycocholic acid GC, taurocholic acid TC, glycochenodeoxycholic acid GCDC, taurochenodeoxycholic acid TCDC, glycodeoxycholic acid GDC, taurodeoxycholic acid TDC, glycoursodeoxycholic acid GUDC and tauroursodeoxycholic acid TUDC in these aspirates was evaluated by liquid chromatography-mass spectrometry-selected ion monitoring analysis LC-MSMS. 