How Common is Inflammatory Bowel Disease (IBD)?

It is estimated that as many as one million Americans have IBD -- with that number evenly split between Crohn's disease and ulcerative colitis. Males and females appear to be affected equally. Crohn's disease may occur in people of all ages, but it is primarily a disease of adolescents and young adults, affecting mainly those between 15 and 35. However, Crohn's disease can also occur in people who are 70 or older and in young children as well. In fact, 10 percent of those affected -- or an estimated 100,000 -- are youngsters under the age of 18.