Inflammatory bowel disease (IBD) is comprised of two major disorders: ulcerative colitis and Crohn disease. Ulcerative colitis and Crohn disease have distinct pathologic and clinical characteristics but their pathogenesis remains poorly understood.
In 2015, an estimated 1.3% of US adults (3 million) reported being diagnosed with IBD (either Crohn's disease or ulcerative colitis). This was a large increase from 1999 (0.9% or 2 million adults).The incidence and prevalence of Crohn disease and ulcerative colitis (UC) appear to be lower in Asia and the Middle East , however, in some newly industrialized countries in Africa, Asia, and South America, the incidence of IBD has been rising.
Ulcerative colitis is a chronic inflammatory condition characterized by relapsing and remitting episodes of inflammation limited to the mucosal layer of the colon. It almost invariably involves the rectum and typically extends in a proximal and continuous fashion to involve other portions of the colon.
Crohn disease is characterized by transmural inflammation and by skip lesions. The transmural inflammatory nature of Crohn disease may lead to fibrosis and strictures, and to obstructive clinical presentations that are not typically seen in ulcerative colitis. The transmural inflammation more commonly results in sinus tracts, giving rise to microperforations and fistulae.
Food antigens are thought to trigger an immunologic response resulting in the development of IBD. However, specific pathogenic antigens have not been identified. While studies attempting to associate specific diets with the development of IBD have had inconsistent results, the data suggest that a "Western" style diet (processed, fried, and sugary foods) is associated with an increased risk of developing Crohn disease, and possibly ulcerative colitis.
To date, studies concerning food intolerance in IBD have largely focused on classic food allergies based on IgE mediated antibody responses. The levels of total or food-specific IgEs have been observed to be increased in the sera of IBD patients, and IgE-mediated food allergies are more frequent in IBD patients than in those without IBDs. Nevertheless, reactions mediated by food specific IgGs, featuring a more delayed response following exposure to a particular antigen, are also expected to contribute to adverse reactions in IBD, and food-specific IgGs help physicians identify the candidate food for elimination in IBD patients. Furthermore, IgG-mediated adverse reactions have also been reported to be involved in some cases of food hypersensitivity.
Elimination diet can help in the remission of the disease. An elimination diet involves removing a food from the diet for a period of time and seeing whether symptoms resolve during that time. In patients receiving enteral nutrition, it involves introducing one new food at a time to identify foods that precipitate IBD symptoms. Many patients can identify foods that they believe may precipitate or worsen their disease and it is reasonable for them to avoid such foods. Using an elimination diet to identify at-risk foods may decrease the possibility of a "flare" of IBD.
