Gluten-Free Diet

A gluten-free diet is a diet that is completely free of gluten, a generic name for a type of storage protein found in certain grains. A gluten-free diet is the prescribed medical treatment for people with gluten intolerance diseases such as celiac disease (also referred to as celiac sprue).

Guidelines for a gluten-free diet were 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 Academy of Nutrition and Dietetics (formerly the American Dietetic Association) also sponsored the development of a gluten-free diet through a cooperative effort of expert dietitians in celiac disease in Canada and the United States.

Gluten-free diets are used to treat and manage gluten intolerance diseases, including celiac disease and dermatitis herpetiformis. Celiac disease is a genetically inherited autoimmune disease. People with celiac disease develop an inflammatory immune system response to gluten that results in damage to parts of the small intestine responsible for the absorption of nutrients.

Gluten-free diet

Some individuals with celiac disease also develop dermatitis herpetiformis, an itchy and blistering skin condition. Dermatitis herpetiformis is often a complication of gluten sensitivity. Approximately 10%–15% of individuals with celiac disease have dermatitis herpetiformis, but 90% of individuals with dermatitis herpetiformis have a gluten sensitivity, indicated by intestinal damage found on an endoscopy. They need to follow a lifelong gluten-free diet.

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. Symptoms typically include gastrointestinal distress, fatigue, and eventually malnutrition. In infancy, celiac disease can cause failure to thrive, diarrhea, abdominal distention, developmental delay, and, in some infants, severe malnutrition.

After infancy, the symptoms of celiac disease are less dramatic. Older children may be short statured or exhibit dental enamel defects. Symptoms of celiac disease can include gastrointestinal problems (e.g. diarrhea and/or constipation, intestinal gas, fatty and foul-smelling stools, bloating, nausea, vomiting), skin irritation, weight loss, missed menstrual periods, unexplained anemia, arthritis, osteoporosis, neurological effects (including seizures and possibly migraine headaches), fatigue, and concentration and memory problems. In some cases, intestinal damage may occur without significant gastrointestinal symptoms. To control symptoms of gluten intolerance, affected individuals must completely avoid foods that contain gluten.

Celiac disease is diagnosed by blood tests for certain antibodies and a 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. It is most important that an individual suspected to have celiac disease continues to eat gluten-containing foods up to the time of the biopsy; otherwise the test may appear as a false negative and be rendered useless. Exclusion of gluten must only occur after diagnosis. Since celiac disease is an inherited autoimmune disease, screening of family members is recommended. Celiac disease is also associated with other autoimmune syndromes such as type 1 diabetes.

Some individuals may exhibit gluten sensitivity with similar gastrointestinal symptoms, but intestinal damage is not seen in a small intestine biopsy. A less intense response to gluten is difficult to diagnose, but it may be confirmed by having the patient follow a gluten-free diet, followed by reintroduction of glutencontaining foods, to evaluate any health changes associated with the elimination or reduction of gluten from the diet. Some individuals with gluten sensitivity are able to tolerate a low-gluten diet under the supervision of a physician or dietitian. No standard agreement has been reached on the appropriate level of gluten intake for individuals exhibiting gluten sensitivity, so a method of trial and error is often necessary.

The foods of concern for individuals with, or susceptible to, celiac disease are the grains that contain the storage proteins prolamin and glutenin (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 any crossbred hybrids (e.g., triticale).

In addition to gluten-containing grains, gluten can be found in a large variety of foods, including:

Unidentified starches, binders, and fillers in medications, supplements, or vitamins, as well as 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.

OATS. Pure, uncontaminated oats eaten in moderation (about one cup cooked daily) may be safe for individuals with celiac disease. However, oats can become cross-contaminated with grains containing gluten during growth, harvest, transport, storage, or processing. Some individuals 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 hypersensitivity to oats and should avoid their consumption. It is recommended that only oats labeled as gluten free are consumed as part of a gluten-free diet. It may also be prudent for individuals with celiac disease to consult their healthcare providers or a registered dietitian before including any other oats in their diet, and they should have their antibody levels monitored regularly.

ALCOHOL. Most beers are brewed with barley or wheat, and thus they should not be consumed by a person following a gluten-free diet. Sorghum and buckwheat beers are increasingly available. Most distilled forms of alcohol are gluten-free, unless additives and colorings containing gluten have been added. Wines are also usually gluten-free.

GLUTEN-FREE FOODS. Some grains and starches that are allowed in a gluten-free diet include rice, corn, soy, potato (and sweet potato), tapioca, and beans. Lesser-known gluten-free grains include gar-fava, sorghum, quinoa, millet, arrowroot, amaranth, teff, nut flours, and buckwheat, although some commercial buckwheat products are mixtures of wheat and buckwheat flours and should be avoided. Other foods that are allowed include fruits; vegetables; cow's milk; aged cheeses; unprocessed meats, poultry, and fish; eggs; dried beans; and nuts and seeds.

Many companies produce gluten-free counterparts to foods that ordinarily contain gluten, such as baking mixes and cereals. Gluten-free foods can be found in health food stores, through mail-order sources, and, increasingly, in regular supermarkets. Cookbooks are available to help in food preparation. Many food manufacturers maintain lists of gluten-free products. A dietitian should be consulted to develop and monitor a gluten-free diet.

The U.S. Food and Drug Administration (FDA) allows manufacturers to label a food or drink as gluten free if it is naturally gluten free or is absent of gluten-containing grains that have not been processed to remove gluten (e.g., wheat flour). Gluten-containing grains that have been processed to remove gluten so that the final product contains less than 20 parts per million (ppm) of gluten in the food can be labeled as gluten free; 20 ppm is the level considered safe for people with celiac disease to consume. Dietary supplements and foods imported into the United States are also subject to this labeling rule. If the product is not labeled as gluten free, celiacs are recommended to check the ingredient lists and also allergen listing. Caution is needed regarding allergen labeling as some gluten-containing allergens do not have to be listed (e.g., barley, rye).

Gluten-free diets are used by individuals who are sensitive to gluten to prevent damage to their small intestines and to prevent serious complications such as gastrointestinal cancers, iron-deficiency anemia, and decreased bone mineral density. The gluten-free diet is recognized by the medical community as the recommended treatment for individuals exhibiting gluten sensitivity.

Gluten-free diets may also be useful in treating other conditions. Research continues on the benefits of a gluten-free diet for individuals with multiple sclerosis and other autoimmune disorders, as well as for individuals with autism spectrum disorders, attention deficit hyperactivity disorder (ADHD), and some behavioral problems.

A gluten-free diet has been shown to greatly reduce the risk for cancer and overall mortality for individuals with symptomatic celiac disease.

Gluten-free recommendations can be difficult to follow. An individual following a gluten-free diet must read labels every time a food item is purchased or consumed. It may be 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; and natural nuts and seeds.

Sometimes it may not be obvious that a product contains gluten. 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 the damage to the small intestine that occurs every time gluten is consumed.

Some seemingly gluten-free foods may still contain gluten by way of cross-contamination, even if gluten is not indicated on the ingredient list. For example, a conveyer belt may be dusted with a gluten-containing material to prevent foods from sticking, which may contaminate the finished food product.

Individuals are more likely to adhere to the diet if a dietitian and support groups are involved. If a person is not responding well to a gluten-free diet, the doctor may:

To monitor dietary adherence to the gluten-free diet, the dietitian examines the person's dietary history and habits. Blood tests are conducted to see if 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.

Gluten-free diets are complex, and it cannot be assumed that chefs in restaurants or others who prepare food (including friends and family) are aware of all of the potential sources of gluten contamination. Education of family and friends is important in accomplishing a lifestyle change. In restaurants, simple dishes without sauces should be ordered, and customers should inquire whether grain products are prepared with the same equipment or utensils used to prepare other foods. Although a food may meet the standards required to be labeled gluten free, it may be contaminated with gluten by the way in which it was prepared or stored. Other potential challenges associated with following a gluten-free diet include travel, where dietary needs may be difficult to accommodate; finding gluten-free foods, especially those of good quality; determining whether foods are gluten free; not being invited out or not wanting to go out because of the diet; and maintaining a gluten-free diet when in the hospital, although a clinical dietitian should be able to assist with accommodating dietary needs.

As with any restrictive diet, a gluten-free diet has potential for nutritional inadequacy. Individuals who are sensitive to gluten are at increased risk for osteoporosis and osteomalacia due to malabsorption of calcium and vitamin D. Calcium and vitamin D supplementation along with strict adherence to a glutenfree diet usually results in remineralization of the skeleton. However, iron or other vitamin deficiencies may also be present and must be treated appropriately. The consumption of gluten-free, fiber-rich foods (e.g., brown rice, fruits, and vegetables) and adequate fluid intake are recommended to assist in the prevention of constipation. Sufferers should be encouraged to consume wholesome naturally gluten-free grains rather than rely too heavily on processed gluten-free products such as cakes and biscuits, which can be high in sugar and lack nutrients.

Women with untreated celiac disease often exhibit a history of miscarriages, anemia, low-birthweight babies, and unfavorable pregnancy outcomes. 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.

With prevalence data revealing that celiac disease is globally present, efforts continue to create awareness and to ensure suitable supports are in place for persons with celiac disease, their families, and their healthcare providers. U.S. and EU food labeling use the term gluten free to mean containing less than 20 ppm (mg/kg) gluten; the EU has an additional benchmark of very low gluten for foods containing less than 100mg/kg (100ppm). Ongoing research ranges from efforts to find less invasive methods for diagnosing celiac disease to enzymes to reduce the amount of gluten in foods and other compounds to treat symptoms associated with celiac disease.

See also Academy of Nutrition and Dietetics ; ADHD diet ; Casein-free diet ; Celiac disease ; Diet apps ; Digestive diseases ; Food sensitivities ; Malnutrition ; Protein ; Weight Watchers .