One of the major underlying causes suggest abnormal activation of the immune system, leading the ulcerations in the intestines. For easy understanding we will divide these factors in two groups i.e. extrinsic and intrinsic factors.

Extrinsic factors:

1. Diet: Intake of ‘junk food’ and low-residue high-refined sugar has been correlated in many studies with susceptibility to have ulcerative colitis. In fact many sufferers of ulcerative colitis notice flare-up of the problem following specific food.

2. Infections: Some researchers feel that ulcerative colitis may be related to certain infections digestive caused by microorganism E. Coli. One theory holds that modern measles virus, improperly cleared from the body, results in low grade, chronic inflammation of the intestinal lining.

3. Drugs: The studies have also shown links between intake of oral contraceptive pills and Ulcerative colitis. May patients experience flare-up of condition following modern medicine drugs like antibiotics and NSAIDs. Isotretinoin, a commonly used drug for severe acne is found to trigger UC and Crohn's disease in some patients.

The important point is although many of us are eating the most-blamed diet or having infection with E. Coli, every one of us is not having ulcerative colitis. This brings us to the conclusion that there must be some roots within an individual, which makes him more susceptible to these environmental factors.

Intrinsic factors:

1. Disturbance of immune system:
Some experts believe that there may be a defect in one’s immune system responsible for ongoing inflammation in the intestinal wall. The disturbance is thought to be either of two.

Allergy: Some studies suggest that Ulcerative colitis is a form of exaggerated allergic response to certain food or to the presence of some microorganisms present in the intestine.

Autoimmunity: Autoimmunity simply means allergy to oneself. Most recent research indicate that ulcerative colitis can be a form of autoimmune disease in which body’s defense system starts attacking body’s own organs and tissues. One amongst them being large intestine.

2. Genetics:
Current research suggests that certain genetic factors may increase the likelihood of person having Ulcerative colitis.

3. Hereditary factors:
If any of your immediate family members is having ulcerative colitis, then your chances of having the disease increases.

4. Psychosomatic:
Mind plays a vital role in maintaining a healthy or diseased condition of the body. Medical community has accepted the fact that any kind of emotional stress has definite detrimental effect on the immune system and hence can be the root cause of chronic disease like ulcerative colitis. In fact, it is a very common experience of physicians that many patients mention that their problem of Ulcerative colitis started after some stressful situations in life or their problem gets worse following stressful events.