Edinburgh May 02, 2007 -- A new study in The American Journal of Gastroenterology suggests that smoking may determine which part of the intestinal tract is attacked in those who suffer from Crohns disease. Where the disease is located often determines whether the patient will eventually require surgical treatment.

"In patients who smoke, Crohns disease tends to appear more frequently in the small intestine, rather than the colon," says study author Dr. Marian Aldhous. "Our data shows that when Crohns disease is located here, it tends to cause more penetrating or obstructive damage, which would have to be treated by surgery."

The results of this study raise interesting questions about why smoking would affect different parts of the intestine in different ways. "Fundamental differences in small and large bowel physiology may explain the differences in location of Crohns disease in smokers," says Aldhous. "The effects of smoking should be further investigated, to understand why smoking has a differential effect on different parts of the bowel."