Frank B. Hu, Walter C. Willett, and Meir J. Stampfer are with the Departments of Nutrition and Epidemiology, Harvard School of Public Health, and the Channing Laboratory, Department of Medicine, Harvard Medical School and Brigham and Women’s Hospital, Boston, Mass. Donna Spiegelman is with the Departments of Epidemiology and Statistics, Harvard School of Public Health. Graham A. Colditz is with the Department of Epidemiology, Harvard School of Public Health, and the Channing Laboratory, Department of...