Causes of Crohn's Disease

Written by Anthony Watt | Published on July 1, 2014
Medically Reviewed by Kenneth R. Hirsch, MD on July 1, 2014

While the causes of Crohn's disease are unknown, researchers have several ideas as to what the culprit may be. Find out what these potential causes are.

Causes of Crohn’s Disease

The causes of Crohn's disease are not known. Diet and stress were once believed to be responsible. However, we now know that these may aggravate the disease, but they do not cause it. Research suggests that a malfunctioning immune system, genetics, and environment may be factors in the development of the disease.

Immune System

A main characteristic of Crohn’s disease is chronic inflammation. Inflammation is a normal immune system response to outside invaders such as viruses, bacteria, and parasites. Some researchers believe that Crohn’s disease may start as a normal response to an outside invader. Then the immune system fails to shut off the attack, resulting in chronic inflammation.

Another theory is that the immune system mistakes the normal bacteria of the intestinal tract for invading microorganisms and responds by attacking them. When your immune system attacks normal parts of your body, it is called an autoimmune disorder.

It is also theorized that the immune system may be mistaking food for an invading organism and attacking what you eat.

Genetics and Heredity

Evidence suggests that genetics plays a large role in the development of Crohn’s disease.

The Crohn’s & Colitis Foundation of America (CCFA) says that according to studies, five to 20 percent of people with Crohn’s disease have a first-degree relative (parent, child, or sibling) with the disease. A specific gene mutation that increases the risk of Crohn’s has also been identified.

Crohn’s disease is more common in people of Northern European and Anglo-Saxon descent and is many times more common in Jewish people of European descent (Ashkenazi Jews) than it is the rest of the population. Crohn’s occurs much less in central and southern Europe and less still in South America, Asia, and Africa. It is beginning to occur more frequently in blacks and Latin Americans living in North America. This and other evidence strongly suggests that heredity alone is not always responsible.


Crohn’s is more common in industrialized nations and in urban areas. People who live in northern climates seem to have a greater risk of developing the disease. This suggests that environmental factors such as pollution, stress, diet, and lifestyle may play a role.

Other Risk Factors

The following factors may increase your risk of developing Crohn’s disease.

Cigarette Smoking

Cigarette smoking seems to contribute to the development of Crohn’s. If you have Crohn’s and smoke, your symptoms are likely to be more severe, and you are more likely to require surgery.


Crohn’s can occur at any age, but most people who develop the disease are diagnosed before age 30.

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