Nearly two million people are affected with IBD [e.g., Crohn’s disease and ulcerative colitis] in the U.S. These inflammatory conditions are a group of several distinct disorders which probably explains the diversity of extent and activity of inflammation within the gastrointestinal (GI) tract. The age of onset is usually in the 20s and 30s, although there is a slight second peak in incidence in the 50s to 60s. Men and women are equally affected in IBD as opposed to IBS, which is female predominant. Revised and updated 2009.