Departments of Epidemiology and Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts; Clinical and Translational Epidemiology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts; Division of Gastroenterology, Massachusetts General Hospital, Boston, Massachusetts. Clinical and Translational Epidemiology Unit, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts; Division of Gastroenterology, Massachusetts General Hospital, Boston, Massachusetts; Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts; Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts; Department of Immunology and Infectious Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Electronic address: achan@mgh.harvard.edu. Division of Gastroenterology and Hepatology, Medicine, Microbiology/Immunology, UIC Cancer Center, University of Illinois at Chicago, Illinois. Electronic address: junsun7@uic.edu.