[1] Harvard Univ, Sch Med, Dept Ambulatory Care & Prevent, Boston, MA 02215 USA
[2] Harvard Pilgrim Hlth Care, Boston, MA 02215 USA
[3] Harvard Univ, Sch Publ Hlth, Dept Nutr, Boston, MA 02115 USA
[4] Brigham & Womens Hosp, Dept Med, Channing Lab, Boston, MA 02115 USA
[5] Harvard Univ, Sch Publ Hlth, Dept Environm Epidemiol, Boston, MA 02115 USA