1. Departamento de Nutricion y Tecnologia de los Alimentos, Univensidad de Chile, Sede Santiago Sur, Casilla 15138, Santiago II, Chile.
2. Tropical Metabolism Research Unit.
3. Medical Research Council. Present address: St. Mary’s Hospital, Praed Street, London, W2, England.
4. Department of Human Nutrition, London School of Hygiene and Tropical Medicine, Keppel Street, London, WCI, England.