What causes Ulcerative Colitis ?
The exact cause of ulcerative colitis is unknown. Researchers believe the following factors may play a role in causing ulcerative colitis:
                
- overactive intestinal immune system  - genes  - environment
                
Overactive intestinal immune system. Scientists believe one cause of ulcerative colitis may be an abnormal immune reaction in the intestine. 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 large intestine. This immune system response causes the inflammation, leading to symptoms.
                
Genes. Ulcerative colitis sometimes runs in families. Research studies have shown that certain abnormal genes may appear in people with ulcerative colitis. However, researchers have not been able to show a clear link between the abnormal genes and ulcerative colitis.
                
Environment. Some studies suggest that certain things in the environment may increase the chance of a person getting ulcerative colitis, although the overall chance is low. Nonsteroidal anti-inflammatory drugs,1 antibiotics,1 and oral contraceptives2 may slightly increase the chance of developing ulcerative colitis. A high-fat diet may also slightly increase the chance of getting ulcerative colitis.3
                
Some people believe eating certain foods, stress, or emotional distress can cause ulcerative colitis. Emotional distress does not seem to cause ulcerative colitis. A few studies suggest that stress may increase a person's chance of having a flare-up of ulcerative colitis. Also, some people may find that certain foods can trigger or worsen symptoms.