Crohn's disease is serious chronic illness that inflicts severe damage to the intestinal tract, causing diarrhea and abdominal pain. Though it can strike anywhere along the GI tract from the mouth to the anus, Crohn's disease usually affects the endmost portion of the small intestine, called the "ileum."

Crohn's disease is an inflammatory condition; the delicate mucous membrane lining the intestinal wall becomes inflamed and ulcerated in spots called "skip lesions." The intestinal lining looks somewhat like an old cobblestone street, with lesions spaced between normal tissue. The inflammation can penetrate the bowel wall, leading to the development of abscesses and deep cracks. Even worse, these cracks may lengthen, forming complete openings from the inside of the intestine to the outside called "fistulas." The intestinal wall eventually becomes hardened and inflexible. In later stages of the disease, the intestine may become obstructed.

Crohn's disease is one of two inflammatory bowel conditions that affect the intestinal lining. The other is ulcerative colitis. The exact cause of these conditions is not known for certain. Both illnesses are thought to have a genetic component. Other contributing factors have been implicated, including food allergies, stress, poor nutrition, and infection. It is also believed that an "autoimmune response," where the immune system attacks the body's own tissue as though it were a foreign invader, may play a role in Crohn's disease. Although Crohn's disease is sometimes mistaken for ulcerative colitis, it has several unique features. Crohn's disease most commonly affects the small or large intestine, while ulcerative colitis shows up in the lower intestine and the rectum. Ulcerative colitis is more common than Crohn's disease, but the incidence of Crohn's appears to be on the rise.(1) Although these conditions hit the gastrointestinal tract hardest, they can lead to many other conditions affecting different parts of the body.(2)

Food allergies and Crohn's disease appear to be closely related. Inflammation and irritation of the intestinal wall cells can eventually increase sensitivity to many foods. When the cells are damaged, they leave gaps between them through which large proteins can penetrate, a phenomenon known as "leaky gut". These molecules, identified as antigens by the immune system, stimulate an inflammatory reaction in the gut lining. Many people afflicted with the disease have identified and eliminated foods that aggravate symptoms. Such foods include chocolate, dairy products, yeast, cereal grains, fats, and artificial sweeteners. In one multicenter trial, subjects with Crohn's disease who followed a diet that excluded the foods they were allergic to remained symptom-free almost twice as long as those receiving standard therapy with corticosteroid drugs treatments.(3)