[1] Tufts Univ, Jean Mayer USDA Human Nutr Res Ctr Aging, Boston, MA 02111 USA
[2] Tufts Med Ctr, Div Endocrinol Diabet & Metab, Boston, MA 02111 USA
[3] US Army Res Inst Environm Med, Mil Nutr Div, Natick, MA 01760 USA
[4] Tufts Med Ctr, Inst Clin Res & Hlth Policy Studies, Boston, MA 02111 USA