1. Drs. Prentice, Moore, and Collison are with the MRC International Nutrition Group, London School of Hygiene & Tropical Medicine, 49-51 Bedford Square, London, WC1B 3DP and MRC Keneba, P.O. Box 273, Banjul, The Gambia, West Africa.
2. Dr. O'Connell is with MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulborn Road, Cambridge, CB1 9NL, United Kingdom.