PPI and Microbiome in Healthy Volunteers and Functional Dyspepsia

Inclusion Criteria: * Subjects aged between 18 and 64 years inclusive * Male or female (not pregnant or lactating and using contraception or postmenopausal) * Normal bowel habits (defecation once every 3 days up to 3 times a day) * Witnessed written informed consent * Access to home freezer (-18 to -20°C) * Capable to understand and comply with the study requirements Exclusion Criteria: * Active psychiatric symptoms (stable dose of single antidepressant allowed) * Use of acid suppressive drugs (before starting Pantomed), immunosuppressants or antibiotics \<3 months before sampling * Use of drugs influencing stool consistency, NSAIDs, anti-allergy drugs, bile acid sequestrants or ursodeoxycholic acid \<2 weeks before sampling * Use of prokinetics \<2 weeks before sampling (unless if ≤3/week) * History of major abdominal surgery, including cholecystectomy but not appendectomy or splenectomy * Personal or family (first-degree relative) history of diabetes mellitus type 1, celiac disease, inflammatory bowel disease, psoriasis, rheumatic or other auto-immune diseases (including therapy) * Allergy or atopy (eczema, asthma and/or allergic rhinoconjunctivitis) (including therapy) * Kidney, liver or coagulation disorders * Active coronary or peripheral artery disease * Diabetes mellitus type 2 (including therapy) * Active malignancy (including therapy) * Known HIV, HBV or HCV infection (including therapy) * Magnetizable objects (e.g. cochlear implants, neural stimulator, pacemaker, metal fragments or implants) or claustrophobia (MRI safety criteria with additional consent form, other procedures can still take place) * Significant alcohol use (\>10 units/weeks) * Any use of alcohol or smoking ≤2 days before sampling * Females who are pregnant or lactating, who are not using contraception and premenopausal