Many studies have shown that there is an association between smoking and the development of Crohn's disease and that it is an independent risk factor for the clinical, endoscopic and surgical recurrence of the disease.

It has been shown that there is a significant increase of recurrence and severity of the disease in all these areas related to the number of cigarettes smoked and the length of time a person has been smoking. Ex-smokers run a similar risk of recurrence to non-smokers with the disease.

Smoking appears to play a significant part in creating a predisposition for the recurrence of the disease due to several possible factors:
1. The intestinal blood supply contains an early element in the pathogenesis of Crohn’s disease - granulomas, which are the hallmark of Crohn's disease, are often found within the walls of blood vessels. This may then cause a vasculitis which some workers have associated with the development of Crohn’s disease.

2. It may alter the composition of mucus in the gut and therefore the protective barrier of the intestinal wall.

3. It may influence the immune response which has also been found to play a part in the pathogenesis of Crohn’s disease.

In view of this evidence we would recommend that you give up smoking (or, indeed, never start!) so as to reduce the likelihood of recurrence of the disease. Not only would it reduce the risk of a relapse of the disease but:
• reduce the risk of developing heart or lung disease
• increase general fitness
• improve skin condition (smoking is known to cause premature ageing)
increase appreciation of food in terms of taste and absorption of vitamins