The importance of the digestive tract is obvious when thinking in terms of obtaining nutrients, energy metabolism and expelling waste, however its protective functions are often overlooked. The small and large intestines provide a barrier between things that are consumed – such as food, medications, pathogenic organisms or insoluble matter – and the blood vessels that transport material to all other organs of the body. For this reason, the intestinal tract is closely interconnected with the immune system, acting as the first line of defense against “offenders”, or antigens, that enter this system and differentiating them from molecules necessary for life. Inflammatory responses triggered in reaction to foreign substances in the gastrointestinal (GI) tract are not uncommon but are usually resolved quickly. Chronic inflammation though can be extremely problematic, and damage created by inflammation that causes penetration of the intestinal barrier can lead to a host of other, more serious complications.
Inflammatory bowel disease (IBD) refers to a group of chronic conditions of the GI tract characterized by recurrent episodes of inflammation, probably resulting from an immune reaction of the body against its own intestinal tissue. Inflammatory markers appear to play an important role in the characteristics and progression of these disorders. Cytokines are released in response to antigens in the GI tract and recruit different types of T cells, a kind of white blood cell, to the area. The immune response disrupts the intestinal mucosa and leads to a chronic inflammatory process.1
The two major types of IBD are ulcerative colitis and Crohn’s disease. These conditions are characterized by ulcerations (breaks in the lining) in the intestinal tract that cause scarring and stiffness of the bowel. Ulcerative colitis is limited to the large intestine, or colon. Crohn’s disease differs from ulcerative colitis in the areas of the bowel it involves; it most commonly affects the last part of the small intestine (called the terminal ileum) and parts of the large intestine. However, it isn’t limited to these areas and can attack any part of the digestive tract from the mouth to the anus. Crohn’s disease causes inflammation that extends much deeper into the layers of the intestinal wall and tends to involve the entire bowel wall, whereas ulcerative colitis affects only the lining of the bowel.2
Crohn’s disease is considered an autoimmune disorder, but the exact cause for the onset of the disease is unknown; therefore, the condition is often referred to as idiopathic inflammatory bowel disease. Scientists have developed multiple theories as to what the cause may be that triggers the body’s immune system to produce uncontrolled inflammation. While the research isn’t conclusive on the causes of inflammatory bowel disease, it is believed that many factors might be involved, including environmental factors (such as geography, cigarette smoking, sanitation and hygiene), infectious microbes, ethnic origin (specifically Ashkenazi Jewish ancestry), genetic susceptibility, and a dysregulated immune system.3,4
Crohn’s disease typically includes periods of remission when inflammation and symptoms subside with occasional flare-ups. Symptoms may range from mild to severe and generally depend upon the part of the digestive tract involved. Although it affects all age groups, onset of symptoms generally occurs between ages of 15 and 30. Because of the involvement of the immune system, symptoms may also appear outside of the digestive tract as well.
Intestinal symptoms may include:
Extra-intestinal symptoms may include:
As Crohn’s disease progresses, many complications can arise. Gastrointestinal complications such as strictures, obstructions or fistulas can require surgery to remove affected areas, but procedures do not address the inflammatory disease itself. After operation, there is a high frequency of recurrence of Crohn’s disease, showing inflammation in 93% of persons 1 year after surgey.5 Long-standing Crohn’s disease patients have a higher risk of developing cancer, predominantly in the small intestine but also the colon if that is where the majority of inflammation occurs. Regular colonoscopies should be conducted to monitor the activity of the intestines.
Malnutrition is often a problem due to the inability to properly absorb nutrients from the damaged intestines. Common deficiencies include vitamin B12, folic acid, iron and fat-soluble vitamins. Some people develop anemia because of low iron levels caused by malabsorption, bloody stools or the intestinal inflammation itself. Crohn’s disease also might delay puberty and retard growth in children or adolescents that contract the disease because they are not receiving the necessary nutrients from food.
As there is no cure for Crohn’s disease, treatment options are designed to reduce inflammation, lessen symptoms and severity, and return to/remain in periods of remission. Treatment might involve medications, nutritional supplements, surgery, or a combination of these therapies. Drug treatment is the main method for relieving symptoms. Anti-inflammatory drugs such as corticosterioids are used to decrease the inflammation and allow for healing, although long-term use of corticosteroids may have debilitating side effects such as osteoporosis. Immunosuppresive agents are also used to prevent the immune system from attacking the body’s own tissues and causing further inflammation. Surgical interventions are left as a last resort for it is not curative in Crohn’s disease, but about 75% of persons will require surgery at some point in time (especially for complications).5 Adjusted diets and restricted foods are often a part of Crohn’s therapy as well.