1. Department of Nutrition, Institute of Basic Medical Science, Faculty of Medicine, University of Oslo, 0316 Oslo, Norway
2. Department of Public Health and Primary Health Care, University of Bergen, 5020 Bergen, Norway
3. Department of Pharmacology, University of Oxford, OX1 3QT Oxford, UK
4. Department of Surveillance and Evaluation, National Institute for Health Development, 11619 Tallinn, Estonia
5. Department of Rheumatology, Haukeland University Hospital, 5021 Bergen, Norway
6. Norwegian Institute of Public Health, 0403 Oslo, Norway