Causes of Crohn's Disease:
The exact cause of Crohn's disease is unknown. Researchers believe the following factors may play a role in causing Crohn's disease:
-- genes
-- environment
-- autoimmune reaction

Genes:
Crohn's disease sometimes runs in families. Research has shown that people who have a parent or sibling with Crohn's disease may be more likely to develop the disease. Researchers continue to study the link between genes and Crohn's disease.

Environment:
Some studies suggest that certain things in the environment may increase the chance of a person getting Crohn's disease, although the overall chance is low. Nonsteroidal anti-inflammatory drugs,1 antibiotics,2 and oral contraceptives2 may slightly increase the chance of developing Crohn's disease. A high-fat diet may also slightly increase the chance of getting Crohn's disease.3

Autoimmune reaction:
Scientists believe one cause of Crohn's disease may be an autoimmune reaction-when a person's immune system attacks healthy cells in the body by mistake. Normally, the immune system protects the body from infection by identifying and destroying bacteria, viruses, and other potentially harmful foreign substances. Researchers believe bacteria or viruses can mistakenly trigger the immune system to attack the inner lining of the intestines. This immune system response causes the inflammation, leading to symptoms.

Some people incorrectly believe that eating certain foods, stress, or emotional distress can cause Crohn's disease. Emotional distress and eating certain foods do not cause Crohn's disease. Sometimes the stress of living with Crohn's disease can make symptoms worse. Also, some people may find that certain foods can trigger or worsen their symptoms.