Brachyspira and Intestinal Allergy-like Immune Reactions in Patients With Irritable Bowel Syndrome (IBS)

Inclusion Criteria: * Patients with IBS diagnosis according to their treating physician (ROME IV). * Association between intake of food and GI symptoms. * Witnessed written informed consent prior to any study procedures. * Patients who are capable to understand the study and the questionnaires, and to comply with the study requirements. Exclusion Criteria: * Patients with relevant concurrent organic GI disease (inflammatory bowel disease, abdominal cancer), or a major disease such as diabetes, uncontrolled thyroid disease, heart disease, kidney disease, liver disease, and active malignant disease (not those that were in remission at least 5 years). * Patients with a history of bowel surgery (not appendectomy or cholecystectomy) that affects GI motility. * Patients with systemic food allergy as evidenced by positive allergy tests (blood, prick test). * Clinical history of severe allergic reactions. * Patients with concurrent major confounding condition(s) based on the clinician's judgement, e.g. DOMINANT psychiatric disorder, vital depression, alcohol or substance abuse in the last 2 year. * Female patients who are pregnant or lactating (females of fertile age are requested to use a safe contraceptive) at the time of inclusion. * Patients who use or used new medications that affect the GI functioning within 1 month before the start of the study.