1. From the Vitamins and Carcinogenesis Laboratory (HEG, JWC, S-WC, MKK, HJ, ZL, and JBM), the Vitamin Metabolism Laboratory (HG, MN, and AJ), and the Biostatistics Unit (GED), Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, and the Forsythe Dental Research Institute, Harvard School of Dentistry, Boston, MA (DM)