1. From the Division of Preventive Medicine (YS and JEM) and the Channing Laboratory (TYL, RMvD, and FBH), Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, and the Departments of Nutrition (TYL, RMvD, and FBH) and Epidemiology (JEM and FBH), Harvard School of Public Health; Boston, MA