Ulcerative Colitis: Overview

What is ulcerative colitis?

Ulcerative colitis (UC) is a chronic disease of the large intestine, also known as the colon, in which the lining of the colon becomes inflamed and develops tiny open sores called ulcers. The combination of inflammation and ulceration can cause abdominal discomfort and bloody diarrhea.

Ulcerative colitis is the result of an abnormal response by the body's immune system. Normally, the cells and proteins that make up the immune system protect from infection. In people with UC, however, the immune system mistakes food, bacteria and other materials in the intestine for foreign or invading substances. When this happens, the body sends white blood cells into the lining of the intestines, where they produce chronic inflammation and ulcers.

It’s important to understand the difference between ulcerative colitis and Crohn’s disease (CD). Crohn’s disease can affect any part of the gastrointestinal (GI) tract, but ulcerative colitis affects only the colon. Additionally, while Crohn’s disease can affect all layers of the bowel wall, ulcerative colitis only affects the lining of the colon.

While both UC and CD are types of Inflammatory Bowel Diseases (IBD), they should not be confused with Irritable Bowel Syndrome (IBS), a disorder that affects the muscle contractions of the colon. IBS does not involve intestinal inflammation.

What causes ulcerative colitis?

Doctors and researchers do not yet know what causes UC. Studies indicate that the inflammation in IBD involves a complex interaction of factors: the genes the person has , the immune-inherited system and something in the environment that triggers the condition.

Foreign substances (antigens) in the environment may be the direct cause of the inflammation, or they may stimulate the body's defenses to produce an inflammation that continues without control. Researchers believe that once the IBD patient's immune system is "turned on" it does not know how to properly "turn off" at the right time. As a result, inflammation damages the intestine and causes the symptoms of IBD. That is why the main goal of medical therapy is to help patients regulate their immune system better.

Who gets ulcerative colitis?

Ulcerative colitis may affect as many as 700,000 Americans. Males and females are equally likely to be affected. In pediatrics, the typical age is 12-14 years, although cases in children under 10 years old are on the rise.

While UC tends to run in families, researchers have been unable to establish a clear pattern of inheritance. Studies show that up to 20 percent of individuals with UC will also have a close relative with the disease. The disease is more common among white people of European origin and among people of European Jewish heritage.

Helpful resources