N=74 Irritable bowel syndrome patients (diagnosed according to Rome III criteria) aged between 18 and 70 and refractory to other therapies were recruited at the Specialized outpatient-clinic for Psychosomatics at the Division of Gastroenterology and Hepatology, Department for Internal Medicine III, University Hospital of Vienna. Antidepressants or anxiolytics and/or ongoing psychotherapy were allowed since severe comorbid psychological problems are a common problem in IBS patients. The study protocol was approved by the ethics committee of the Medical University of Vienna (ID: 1488/2012). Informed consent in writing was given by each participant.