As anyone who has been diagnosed with Crohn's disease will know, there is no known cause that is recognized as grounds for the disease. There is no shortage of theories that purport to account for how the disease is triggered, although none have been adequately proven.

Among the popular theories is the idea that Crohn's disease is in fact a systemic reaction to bacterium, or perhaps the immune systems response to a virus within the digestive system. According to this theory, what we know to be Crohn's disease is in fact the body protecting itself from a perceived threat in the digestive tract by inflaming the intestine. There is certainly a degree of evidence to support these claims.

People who suffer from Crohn's disease have a high incidence of abnormalities of the immune system. This does seem to support the aforementioned theory quite well, although doctors are unable to confirm weather this abnormality is a cause for the disease or actually a result of Crohn's disease itself.

Rather than sift through a range of theories perhaps it is more useful to begin by taking a look at what we actually know about the disease. Firstly, there are a number of predisposing factors that have been observed to play a role in the development of Crohn's disease. These factors are:

-Genetics and Family History
-Infection
-Immunological Factors
-Diet
-Psychological Factors and
-Measles and MMR vaccine

Genetics has been investigated and studies have shown that statistically, there is an increased chance for family members if one member has Crohn's disease. This hereditary tendency demonstrates considerable variation in risk levels, although most studies indicate that the highest risk exists when a sibling has the disease. Where twins are concerned, the risk is further increased for identical twins.

Infection is not regarded as a major concern for Crohn's disease but some people have developed the Crohn's after a bout of gastroenteritis.

Immunological factors draw the most attention from doctors with regard to investigating the cause of Crohn's disease. This is obviously due to the fact that the reaction of the immune system is the central part of Crohn's. It is also the area where many drugs attempt to control Crohn's through immune suppression.

Diet is a popular area for experimentation due to the fact that it is an inexpensive way for patients to address their symptoms. Diet related treatments have varying degrees of success but there is a general consensus among people with Crohn's disease that certain foods such as wheat, yeast and milk should be avoided.

As far as psychological factors are concerned, emotional stress has been linked to Crohn's disease but there is no hard proof to support the link.

Measles and MMR vaccines have received some publicity in recent times, but further studies of this area have not yielded any consistent results. Unfortunately, at present there is not enough evidence to clearly state weather or not children should be vaccinated for measles.