1. From the MRC Childhood Nutrition Research Centre, Institute of Child Health, London, United Kingdom (MSF and AL); the School of Biomedical and Molecular Sciences, University of Surrey, Guildford, United Kingdom (JBM); the Clinical Nutrition Service, Division of GI/Nutrition, Children's Hospital, Boston, MA (CD); the Center for Child Health Services, Reykjavík, Iceland (GG); the Clinical Research