1. Department of International Health, Division of Human Nutrition, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
2. Blizard Institute, Queen Mary University of London, London, UK
3. Zvitambo Institute for Maternal and Child Health Research, Harare, Zimbabwe
4. College of Health Sciences, University of Zimbabwe, Harare, Zimbabwe
5. MRC Clinical Trials Unit at University College London, London, UK
6. School of Population and Public Health, University of British Columbia, Vancouver, Canada