Celiac disease is an autoimmune condition triggered by gluten, proteins found in wheat, barley and rye. In this instance, the target of the body's assault on itself are villi, hair-like structures within the small intestine that produce digestive enzymes and play a vital role in transforming food into nourishment. Current estimates are that about 1 percent of the American population suffers from celiac disease but about 10 percent have other forms of gluten sensitivity.
The Small Intestine
If uncoiled, the small intestine, where the process of digestion is completed, would measure more than 20 feet. Millions of tiny protrusions called villi line the inner walls of a healthy small intestine, greatly increasing the surface area, which boosts the efficiency of the digestive process. The villi also produce the digestive enzymes necessary for breaking down fats, proteins and carbohydrates into nutrient components. After this is done, the villi absorb these nutrients and transfer them to the bloodstream. Waste products are shunted to the large intestine and are eventually eliminated from the body as feces.
Gliadin and Celiac Disease
Celiac disease involves an autoimmune system dysfunction triggered by gliadin, the allergenic substance in wheat gluten; barley and rye both contain similar allergens. After gliadin is absorbed into the villi, the immune systems of people with CD respond by flooding the bloodstream with two kinds of antibodies. Anti-tissue transglutaminase targets one digestive enzyme that helps repair damaged tissue, and anti-endomysium attacks the connective tissue enclosing muscle and nerve fibers. For a confirmed diagnosis of CD, both these antibodies must show up in a blood test, and a biopsy of the small intestine must reveal signature damage to the villi. Instead of standing up like the pile of a carpet, the villi are flattened.
Enzyme Production Impaired
Every time a person with CD ingests gluten, even trace amounts, the immune system renews its attack on the small intestine. The injured villi, unable to manufacture the digestive enzymes that break down food, also can't absorb nutrients required by the body, no matter how much food is eaten. The antibodies coursing through the bloodstream may target other systems, confounding accurate diagnosis with symptoms that may have no obvious connection to the gastrointestinal tract, including skin rashes, hair loss, joint pain, depression, changes in tooth enamel, anemia and osteoporosis. Drugs to detoxify gluten before it reaches the small intestines of people with CD are under development but at present, the only treatment is lifelong adherence to a strict gluten-free diet.
Why CD Rates Are Rising: Theories
Joseph Murray, M.D., a Mayo Clinic gastroenterologist, says that the prevalence of CD is soaring so dramatically that it is becoming a public health issue. Some "pervasive" environmental influence must be at work to account for this, he believes. One theory, the "hygiene" hypothesis, holds that modern living environments have been so over-sanitized that the immune system, left with little else to attack, turns on itself. Diets have also changed radically since the 1950s when, as Murray's research has shown, CD was still a rare disease in the US. The strains of wheat consumed today are genetically different from older varieties because they've been hybridized to maximize gluten content; it's possible that the immune systems of vulnerable people are rebelling against the overdose.
References
- Harvard Health Publications; Getting Out the Gluten; June 2009
- Gastroenterological Society of Australia: Small Intestine
- University of Chicago Celiac Disease Center: Antibody Blood Tests
- Gluten Website Glossary: Gluten
- Discovery's Edge; "Celiac Disease: On the Rise"; Barbara Toman; July 2010
- CNN Health; "Will a Gluten-Free Diet Improve Your Health?"; Carina Storrs; April 12, 2011
