1 Department of Pharmacology, University of Oxford, Oxford, UK.
2 Department of Physiology, Faculty of Medicine, University of Alexandria, Alexandria, Egypt.
3 Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Blindern, Postboks 1046, Oslo, Norway.
4 The Cancer Registry of Norway, Oslo University Hospital, Oslo, Norway.
5 Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, Blindern, Postboks 1046, Oslo, Norway. thomas.olsen@medisin.uio.no.