1. Center of Integrative Medicine, Witten/Herdecke University, Gerhard-Kienle-Weg 4, 58313 Herdecke, Germany
2. Department of Internal and Integrative Medicine, Kliniken Essen-Mitte, University of Duisburg-Essen, 45276 Essen, Germany
3. Department of True Naturopathy, Blankenstein Hospital, Im Vogelsang 5-11, 45527 Hattingen, Germany