Inclusion Criteria:  Based on medical history and previous self-admitted examination, no gastrointestinal complaints and/or disease can be defined. Age between 18 and 65 years. Body Mass Index (BMI) between 20 and 30 kg/m2.  Exclusion Criteria:  History of severe cardiovascular, respiratory, urogenital, gastrointestinal/hepatic, hematological/immunologic, HEENT (head, ears, eyes, nose, throat), dermatological/connective tissue, musculoskeletal, metabolic/nutritional, endocrine, neurological/psychiatric diseases, allergy, major surgery and/or laboratory assessments which might limit participation in or completion of the study protocol. The severity of the disease (major interference with the execution of the experiment or potential influence on the study outcomes) will be decided by the principal investigator. Use of medication, including vitamin supplementation, pre- and probiotic supplementation, except oral contraceptives, within 14 days prior to testing. Administration of investigational drugs or participation in any scientific intervention study, which may interfere with this study (to be decided by the principal investigator), in the 180 days prior to the study. Major abdominal surgery interfering with gastrointestinal function (uncomplicated appendectomy, cholecystectomy and hysterectomy allowed, and other surgery upon judgement of the principal investigator). Pregnancy, lactation. Excessive alcohol consumption (> 14 alcoholic consumptions per week). Smoking. Drug use. Blood donation within 3 months before or after the study period. Self-admitted HIV-positive state. Plan to lose weight or follow a specific diet (e.g. weight loss or gluten-free diet) within the study period.