Causes

The exact cause of Crohn's disease remains unknown. Previously, diet and stress were suspected, but now doctors know that these factors may aggravate, but don't cause, Crohn's disease. Several factors, such as heredity and a malfunctioning immune system, likely play a role in its development.

• Immune system. It's possible that a virus or bacterium may trigger Crohn's disease; however, scientists have yet to identify such a trigger. When your immune system tries to fight off the invading microorganism, an abnormal immune response causes the immune system to attack the cells in the digestive tract, too.
• Heredity. Crohn's is more common in people who have family members with the disease, so genes may play a role in making people more susceptible. However, most people with Crohn's disease don't have a family history of the disease.