1. Department of Nutrition, Exercise and Sports, University of Copenhagen, 1958 Frederiksberg C, Denmark
2. Department of Paediatrics and Child Health, School of Medicine, College of Health Sciences, Makerere University, Kampala P.O. Box 7072, Uganda
3. Department of Clinical Biochemistry, Aarhus University Hospital, 8200 Aarhus N, Denmark
4. Tampere Center for Child, Adolescent and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University, 33100 Tampere, Finland
5. National Institute of Public Health, University of Southern Denmark, 5230 Odense M, Denmark
6. Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK