1. Policy, Planning and Strategy Division, World Food Programme, Rome 00148, Italy
2. Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA 02111
3. Programme Design and Support Division, World Food Programme, Rome 00148, Italy
4. Agriculture and Rural Development, World Bank, Washington, DC 20433
5. Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205