1. Research Centre, Akershus University Hospital, 1478 Lørenskog, Norway
2. Faculty of Health, Nutrition and Management, Akershus University College, P.O. Box 423, 2001 Lillestrøm, Norway
3. Institute of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1432 Aas, Norway
4. Section of Preventive Medicine and Epidemiology, University of Oslo, P.O. Box 1130, Blindern, 0318 Oslo, Norway
5. EpiGen Institute, Research Centre, Akershus University Hospital, 1478 Lørenskog, Norway
6. Department of Gastroenterology, Rikshospitalet University Hospital, 0027 Oslo, Norway