[1] Georgetown Univ, Sch Med, Washington Hosp Ctr, Gastroenterol Sect, Washington, DC 20057 USA
[2] Univ Chicago, Joseph B Kirsner Ctr Study Digest Dis, Chicago, IL 60637 USA
[3] Rush Univ, Med Ctr, Dept Clin Nutr, Chicago, IL 60612 USA
[4] IIT, Pritzker Inst Biomed Sci & Engn, Chicago, IL 60616 USA