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A gluten-free diet is a diet that is completely free of gluten, which is a generic term for storage proteins found in grains. In celiac disease (also referred to as celiac sprue), persons develop an inflammatory immune system response to gluten that results in damage to the small intestine, which inhibits absorption of nutrients. Some persons also develop dermatitis her-petiformis, an itchy and blistering skin condition. Because of gluten intolerance, affected persons must completely avoid foods that contain gluten.
Guidelines for this diet have been developed by dietitians for several organizations associated with celiac disease and dermatitis herpetiformis, including the Gluten Intolerance Group, the Celiac Sprue Association, and the Celiac Disease Foundation. The American Dietetic Association also sponsored the development of a gluten-free diet through a cooperative effort of dietitian experts in celiac disease in Canada and the United States, which was published in October, 2000.
The gluten-free diet is the prescribed medical treatment for gluten intolerance diseases, including celiac disease and dermatitis herpetiformis. Celiac disease is a genetically inherited, chronic digestive disease that results in damage to parts of the small intestine that are responsible for absorption of nutrients. Celiac disease affects almost three million people in the United States, about one percent of the population. Celiac disease is found among North American and European populations, where wheat is a staple food, but is found infrequently among descendants of China and Japan and persons with an African-Caribbean background, where wheat is not as widely consumed.
In addition, dermatitis herpetiformis is an important disorder or complication of gluten-sensitive enter-opathy, which is manifested in the form of a skin rash. Approximately 10% of persons with celiac disease have dermatitis herpetiformis, but about 85% of persons with dermatitis herpetiformis also have celiac disease.
When a person with celiac disease consumes gluten, the villi of the small intestine, where absorption of key nutrients takes place, become damaged, resulting in nutrients passing through the digestive system without being absorbed. The person exhibits gastrointestinal distress and eventually malnutrition. In infancy, celiac disease manifests itself as failure to thrive, diarrhea, abdominal distention, developmental delay, and in some infants, as severe malnutrition.
After infancy, the symptoms of celiac disease are less dramatic. Older children may be short or exhibit dental enamel defects. Women comprise about 75% of newly diagnosed adult cases of celiac disease. Symptoms of celiac disease include diarrhea, constipation alternating with diarrhea, intestinal gas, fatty, greasy, foul-smelling stools, bloating, nausea, vomiting, skin irritation, weight loss, anemia, neurological effects (including seizures, and possibly migraine headaches), fatigue, concentration and memory problems. In some cases, there may be intestinal damage without significant gastrointestinal symptoms. Celiac disease is diagnosed by blood tests for certain antibodies and small intestine biopsy. A positive small intestine biopsy, followed by an improvement in health after following a gluten-free diet, is confirmation of celiac disease. A gluten-free diet should not be started before diagnosis is confirmed.
Some individuals may exhibit gluten intolerance, with gastrointestinal symptoms similar to those seen with celiac disease, but without its resulting intestinal damage. Gluten intolerance is diagnosed by following
(Illustration by GGS Information Services/Thomson Gale.)
A gluten-free diet, followed by reintroduction of gluten- containing foods, to evaluate health improvement associated with elimination or reduction of gluten from the diet. Some individuals with gluten intolerance maybe be able to tolerate a low-gluten diet under the supervision of a physician or dietitian.
A gluten-free diet may also be helpful for persons with multiple sclerosis and other autoimmune disorders, as well as for persons with autism spectrum disorders, Attention Deficit Hyperactivity Disorder (ADHD), and some behavioral problems.
The foods of concern for individuals with, or susceptible to, celiac disease are the cereal grains that contain the storage proteins prolamin and glutelin (commonly referred to as glutens in wheat), including all varieties of wheat (e.g., durum, spelt, kamut), barley (where the storage proteins are called hordiens), rye (where the storage proteins are called secalins), and their cross-bred hybrids (such as triticale).
Grains and starches that are allowed in a gluten-free diet include: rice, corn, soy, potato, sweet potato, tapioca, beans, garfava, sorghum, quinoa, millet, arrowroot, amaranth, tef, nut flours, and buckwheat. However, some commercial buckwheat products are mixtures of wheat and buckwheat flours and should be avoided. Other foods that are allowed (only a partial list) include fresh, canned, and frozen fruit or fruit juices, fresh vegetables, canned and frozen vegetables without gluten-containing additives, milk, aged cheese, all unprocessed meats, poultry, fish, eggs, dried beans, nuts, and seeds. A dietitian should be consulted to develop and monitor a gluten-free diet.
Gluten-free foods can be found in health food stores, through mail order sources, and in some supermarkets. Cookbooks are available to help in food preparation. Many food manufacturers maintain lists of gluten-free products. The Gluten-Free Certification Organization (GFCO) of the Gluten Intolerance.
Group, in cooperation with the Food Services, Inc., a subsidiary of the Orthodox Union, a kosher certification agency, has developed a gluten-free certification program. This program benefits consumers by giving them confidence that a product is gluten-free through a process whereby products have been tested and the manufacturing site inspected. The program also saves the consumer time that would have been spent calling the manufacturer for the gluten-free status of the product. Certification is a yearly process based on ingredient review, on-site inspection and product testing. The Celiac Sprue Association (CSA) also has the CSA Recognition Seal Program that certifies gluten-free products. Requirements for obtaining the CSA Seal for products include:
- Ingredient review and verification by testing to assure products are free of wheat, barley, rye and oats
- Provision of written facility procedures and on-site facility audits to assure that procedures are in place to control any cross or outside contamination in processing and packaging
Foods may contain gluten, although gluten will not be indicated on the ingredient list, because it was not included in the formulation of the product. For example, a conveyer belt may be dusted with a gluten-containing material to prevent foods from sticking and may contaminate the finished food product.
The gluten-free diet is used by persons who are gluten-sensitive to prevent damage to their small intestines and to prevent serious complications such as gastrointestinal cancers, iron-deficiency anemia, and decreased bone mineral density.
A gluten-free diet has been shown to greatly reduce the risk for cancer and overall mortality for individuals with symptomatic celiac disease.
For many people with celiac disease, following a gluten-free diet will stop the symptoms of the disease and result in improved health, usually within several months (for some persons, recovery may take up to one year) However, the health of some people with extensive damage to their small intestines may not improve. Refractory coeliac disease (RCD) is a rare syndrome with a poor prognosis, defined by malabsorption due to gluten-related enteropathy after initial or subsequent failure of a strict gluten-free diet and after exclusion of any other disease or disorder mimicking celiac disease. Other treatments may be necessary to treat the RCD, such as the use of corticosteroids and immuno-suppressant drugs, but data on their effectiveness is lacking.
In addition to gluten-containing grains, gluten can be found in a large variety of foods including soups, salad dressings, processed foods, candy, imitation bacon and seafood, marinades, processed luncheon meats, sauces and gravies, self-basting poultry, soy sauce or soy sauce solids, thickeners, communion wafers, and natural flavorings. Unidentified starch, binders and fillers in medications. supplements, or vitamins and adhesives in stamps and stickers can also be unsuspected sources of gluten. Playdough, which contains wheat, can be harmful if hands are put on or in the mouth after contact or hands are not washed after play.
An individual following a gluten-free diet must read labels every time a food item purchased or consumed. Ingredients that may contain hidden sources of gluten include unidentified starch, modified food starch, hydrolyzed vegetable or plant protein (HVP or HPP), texturized vegetable protein (TVP), and binders, fillers, and extenders. In addition, manufacturers can change ingredients at any time, and a product may no longer be gluten-free. Ingredients may be verified by contacting a manufacturer and specifying the ingredient and lot number of a food item. If a person cannot verify ingredients in a food product or if the ingredient list is unavailable, the food should not be eaten, to avoid damage to the small intestine that occurs every time gluten is consumed.
Gluten-free recommendations can be difficult to follow. It is recommended that an affected person keeps the diet simple at the beginning by eating fresh fruits and vegetables, milk, unprocessed protein foods such as fresh beef, pork, poultry, fish, and eggs, natural nuts, seeds, and vegetable oils without additives.
Pure, uncontaminated oats eaten in moderation (one cup cooked daily) may be safe for persons with celiac disease. However, in many cases oats can become cross-contaminated with grains containing gluten during growth, harvest, transport, storage, or processing. Some persons with celiac disease who introduce oats to their diet may experience abdominal discomfort, gas, and stool changes until they become accustomed to the increased fiber levels from the oats. Others with celiac disease may exhibit a hypersensitiv-ity to oats and should avoid their consumption. Recent research published in the last few years (2000 to 2004) has indicated that oats may contain a protein similar to gluten that has caused intestinal inflammation in many persons with celiac disease. At this time, because of conflicting information on the effects of oats on persons with celiac disease, excluding oats from the diet may be the best and most risk-free choice. In all cases, persons with celiac disease should consult their health care provider or dietitian before including oats in their diet and should have their antibody levels monitored regularly.
Almost all beers are brewed with barley (some are brewed with wheat) and should not be consumed by a person following a gluten-free diet. Sorghum and buckwheat beers are available but are a specialty product. Most distilled forms of alcohol are gluten-free, unless additives and colorings have been added, which may contain glutens. Wines are also usually gluten-free.
Since celiac disease is an inherited autoimmune disease, screening of family members is recommended. The chances of developing gluten-sensitive enteropathy increases to 10 to 20% in persons who have a first-degree relative with celiac disease. Celiac disease is also associated with other autoimmune syndromes such as Type 1 diabetes.
A gluten-free diet is difficult to follow, and continued health problems are usually associated with problems with adhering to the gluten-free diet. A person can exhibit celiac-related symptoms for months after a single gluten intake. Persons with gluten-sensitivity who do not treat their disease are at a higher risk for enteropathy-associated T-cell lymphoma and other gastrointestinal cancers. However, the maintenance of a long-term gluten-free state reduces the risk of lymphoma to the level seen in the general population. Other complications of gluten-sensitivity include decreased mineral bone density and iron-deficiency. Persons with celiac disease and dermatitis herpetiformis must maintain a gluten-free diet for the rest of their lives, for these diseases cannot be cured.
Persons are more likely to adhere to the diet if a dietitian and support group are involved. If a person is not responding well to a gluten-free diet, the doctor should:
- Investigate whether the initial diagnosis of celiac disease was correct
- Check for other conditions that can be causing symptoms, such as pancreatic insufficiency, irritable bowel syndrome, bacterial overgrowth, lymphocytic colitis, T-cell lymphoma, fructose intolerance, or tropical sprue
- Refer the person to a dietician to check for errors in the diet or for compliance with the diet
To monitor dietary adherence to the gluten-free diet, the dietitian will examine the person’s dietary history and habits. Blood tests will be conducted to see is gluten antibody levels have returned to normal levels. If there is clinical concern that a person is not adhering to the gluten-free diet or that the diet is not effective, a biopsy of the small intestine may be conducted.
The gluten-free diet is complex and it cannot be assumed that chefs in restaurants or others who prepare food (including friends and family) are aware of potential sources of gluten contamination. Education of family and friends is important in accomplishing a life-style change. In restaurants simple dishes without sauces should be ordered, and the person should inquire whether grain products are prepared with the same equipment or utensils used to prepare other foods. Although a food may be considered to be gluten-free by the ingredients it contains, it may be gluten-contaminated by the way in which it is prepared or stored. Other difficulties associated with following a gluten-free diet include lifestyle changes such as avoiding travel, finding gluten-free foods, especially those of good quality, determining whether foods are gluten-free, not being invited out because of the diet, with resulting social isolation, and maintaining a gluten-free diet when in the hospital.
As with any restrictive diet, the gluten-free diet has potential for nutritional inadequacy. Persons who are sensitive to gluten are at increased risk for osteoporosis and osteomalacia, due to malabsorption of calcium and vitamin D. Most persons with celiac disease have some degree of osteopenia or osteoporosis. Calcium and vitamin D supplementation along with strict adherence to a gluten-free diet usually results in remineralization of the skeleton. Iron or other vitamin deficiencies may also be present and must be treated appropriately. The consumption of gluten-free fiber-rich foods (for example, brown rice, fruits, and vegetables) and adequate fluid intake is recommended to assist in the prevention of constipation.
Women with untreated celiac disease often exhibit a history of miscarriages, anaemia, low birth weight babies, and unfavorable outcome of pregnancy. It is suggested that testing for celiac disease be included in the battery of tests prescribed for pregnant women. Celiac disease is considerably more common than most of the diseases for which pregnant women are routinely screened. Unfavorable events associated with celiac disease may be prevented by a gluten-free diet.
The gluten-free diet is recognized as the required treatment for persons exhibiting gluten-sensitivity.
The National Institutes of Health noted in 2004 that the strict definition of a gluten-free diet remains controversial due to the lack of an accurate method to detect gluten in food products and the lack of scientific evidence for what constitutes a safe amount of gluten ingestion. No international agreement has yet been developed on how much gluten a person with gluten-sensitivity can tolerate. Research is on-going to better identify levels that are acceptable, and health professionals involved in the therapy of celiac disease should keep up-to-date on the latest research. As of February, 2007, the United States Food and Drug Administration is proposing to set a standard of 20 part per million as the maximum acceptable level of gluten allowed for a product to be labeled as gluten-free.
Research continues on the benefits of a gluten-free diet for persons with multiple sclerosis and other autoimmune disorders, as well as for persons with autism spectrum disorders, ADHD, and some behavioral problems.
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Celiac Disease Foundation, 13251 Ventura Boulevard, Suite 1, Studio City, CA 91604-1838; Telephone: (818) 990-2354; Website: [www.celiac.org].
Celiac Sprue Association, P.O. Box 3170, Omaha, NE 68131-0700. Telephone: (877) 272-4272; E-mail: [firstname.lastname@example.org]; Website: [www.csaceliacs.org]
Gluten Intolerance Group, 31214 124th Avenue SE, Auburn, WA 98092-3667. Telephone: (253) 883-6655; Website: [www.gluten.net]
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The University of Maryland Center for Celiac Research. 20 Penn Street, Room S303B Baltimore, MD 21201. Clinic: University of Maryland Medical Center 22 S. Greene Street (N5W40) Baltimore, MD 21201. Telephone: (410) 328-6749 or (800) 492-5538. Website: [www.celiaccenter.org/]
Judith L. Sims