1. Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California 94720; Laboratório de Bioquímica Nutricional e de Alimentos, Departamento de Bioquimica, Instituto de Quimica, Universidade Federal do Rio de Janeiro, 21949–900 Rio de Janeiro, Brazil; Department of Molecular and Cell Biology, University of California, Berkeley, California 94720; and USDA Western Human Nutrition Research Center, Davis, California 95616