1. Department of Internal Medicine, Maastricht University Medical Center, Maastricht, Limburg, The Netherlands
2. Gastroenterology Department, Royal London Hospital, London, UK
3. Wingate Institute of Neurogastroenterology, Queen Mary University of London, London, UK
4. Department of Internal Medicine, Division of Gastroenterology-Hepatology, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Center, PO box 5800, Maastricht, Limburg 6202 AZ, The Netherlands