The American Gastroenterological Association (AGA) is dedicated to the mission of advancing the science and practice of gastroenterology. Founded in 1897, the AGA is one of the oldest medical-specialty societies in the U.S. Our 16,000 members include physicians and scientists who research, diagnose and treat disorders of the gastrointestinal tract and liver. The AGA Institute runs the organization’s practice, research and educational programs.

The content in the series of AGA Institute patient education brochures was reviewed by the following gastroenterologists:

John I. Allen, MD, MBA, AGAF
Minnesota Gastroenterology
Chair, AGA Clinical Practice & Quality Management Committee

Harry R. Aslanian, MD
Yale University School of Medicine

Stephen J. Bickston, MD, AGAF
University of Virginia Health System

Joel V. Brill, MD, AGAF
Predictive Health LLC
Chair, AGA Practice Management & Economics Committee

Marcia I. Canto, MD, MHS
Johns Hopkins University

Richard Davis, Jr. PA-C
University of Florida College of Medicine

Mark H. DeLegge, MD, AGAF
Medical University of South Carolina

Kenneth DeVault, MD
Mayo Clinic, Jacksonville

Stephen W. Hiltz, MD, MBA, AGAF
TriState Gastroenterology

Lawrence R. Kosinski, MD, MBA, AGAF
Elgin Gastroenterology, S.C.

Linda A. Lee, MD, AGAF
Johns Hopkins School of Medicine

Stephen A. McClave, MD, AGAF
University of Louisville School of Medicine

Kimberley Persley, MD
Texas Digestive Disease Consultants

John Schaffner, MD
Mayo Clinic, Rochester

Joanne A.P. Wilson, MD, FACP, AGAF
Duke University Medical Center

Cynthia M. Yoshida, MD, AGAF
University of Virginia Health System

Atif Zaman, MD, MPH
Oregon Health and Science University

The Digestive Health Initiative® (DHI) is an AGA Institute initiative that offers educational programs on digestive disorders for individuals who are affected by a digestive disease, in an effort to educate the larger health-care community.

This brochure was produced by the AGA Institute and funded by a grant from Takeda Pharmaceutical Products Inc.

For more information about digestive diseases, please visit the AGA Web site at

The AGA Institute offers the information in these brochures for educational purposes to provide accurate and helpful health information for the general public. This information is not intended as medical advice and should not be used for diagnosis. The information in these brochures should not be considered a replacement for consultation with a health-care professional. If you have questions or concerns about the information found in these brochures, please contact your health-care provider. We encourage you to use the information and questions in these brochures with your health-care provider(s) as a way of creating a dialogue and partnership about your condition and your treatment.