A gluten-free diet is a diet that excludes foods containing gluten. Gluten is a protein found in wheat (including kamut and spelt), barley, rye, malts and triticale. It is used as a food additive in the form of a flavoring, stabilizing or thickening agent, often as "dextrin". A gluten-free diet is the only medically accepted treatment for celiac disease,[1] the related condition dermatitis herpetiformis,[2] and wheat allergy.[1]
Additionally, a gluten-free diet may exclude oats. Medical practitioners are divided on whether oats are an allergen to celiac disease sufferers[3] or if they are cross-contaminated in milling facilities by other allergens.[4]
The term gluten-free is generally used to indicate a supposed harmless level of gluten rather than a complete absence.[5] The exact level at which gluten is harmless is uncertain and controversial. A recent systematic review tentatively concluded that consumption of less than 10 mg of gluten per day is unlikely to cause histological abnormalities, although it noted that few reliable studies had been done.[5] Regulation of the label gluten-free varies widely by country. In the United States, the FDA issued regulations in 2007 limiting the use of "gluten-free" in food products to those with less than 20 ppm of gluten.[6][7] The current international Codex Alimentarius standard allows for 20 ppm of gluten in so-called "gluten-free" foods.[8]
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Several grains and starch sources are considered acceptable for a gluten-free diet. The most frequently used are corn, potatoes, rice, and tapioca (derived from cassava). Other grains and starch sources generally considered suitable for gluten-free diets include amaranth, arrowroot, millet, montina, lupin, quinoa, sorghum (jowar), taro, teff, chia seed, and yam. Various types of bean, soybean, and nut flours are sometimes used in gluten-free products to add protein and dietary fiber. Almond flour is a low-carbohydrate alternative to flour, with a low glycemic index. In spite of its name, buckwheat is not related to wheat; pure buckwheat is considered acceptable for a gluten-free diet, although many commercial buckwheat products are actually mixtures of wheat and buckwheat flours, and thus not acceptable. Gram flour, derived from chickpeas, is also gluten-free (this is not the same as Graham flour made from wheat).
Gluten is also used in foods in some unexpected ways, for example as a stabilizing agent or thickener in products like ice-cream and ketchup.[9][10]
People wishing to follow a completely gluten free diet must also take into consideration the ingredients of any over-the-counter or prescription medications and vitamins. Also, cosmetics such as lipstick, lip balms, and lip gloss may contain gluten and need to be investigated before use. Glues used on envelopes may also contain gluten.
Most products manufactured for Passover are gluten free. Exceptions are foods that list matzah as an ingredient, usually in the form of cake meal.[11]
A gluten-free diet allows for fresh fruits, vegetables, meats and many dairy products. The diet allows rice, corn, soy, potato, tapioca, beans, sorghum, quinoa, millet, buckwheat, arrowroot, amaranth, teff, Montina and nut flours and prohibits the ingestion of wheat, barley, rye and related components, including triticale, durum, graham, kamut, semolina, spelt, malt, malt flavouring or malt vinegar.[12]
In the US, the FDA considers foods containing less than or equal to 20 ppm to be gluten-free. The finding of a current study indicates that some inherently gluten-free grains, seed, and flours not labeled gluten-free are contaminated with gluten. The consumption of these products can lead to inadvertent gluten intake. [13] The use of highly sensitive assays is mandatory to certify gluten-free food products. The European Union, World Health Organization, and Codex Alimentarius require reliable measurement of the wheat prolamins, gliadins rather than all-wheat proteins. [14] There is still no general agreement on the analytical method used to measure gluten in ingredients and food products. [15] The official limits described in the Codex Draft are 20 ppm for foodstuffs naturally gluten-free and 200 ppm for foodstuffs rendered gluten-free. [16] The ELISA method was designed to detect w-gliadins but it suffered from the setback that it lacked sensitivity for barley prolamins.[17]
A growing body of evidence suggests that a majority of people with celiac disease and following a gluten-free diet can safely consume pure oats in moderate amounts. But, previous studies have indicated that the commercial oat supply in other countries and in Canada is contaminated with other grains. [18]
Special care is necessary when checking product ingredient lists since gluten comes in many forms: vegetable proteins and starch, modified food starch (when derived from wheat instead of maize), malt flavoring, including maltodextrine, dextrine , unless specifically labeled as corn malt. Many ingredients contain wheat or barley derivatives. However, dextrose is gluten free since it is highly modified, no matter what the source.[19]
Although many foods contain gluten, it is not always included in ingredients lists. This lack of inclusion is because gluten is not used in the formulation of the product, but in the preparation (or manufacturing) of listed ingredients. One example is the dusting of the conveyor belts in the production facilities with gluten products to prevent the foods from sticking during processing. "Natural flavoring" is also suspected to contain gluten. This type of gluten contamination may not be labeled; information confirming whether this form of gluten is present in a given product may only be available by contacting the food manufacturer directly.
The suitability of oats in the gluten-free diet is still somewhat controversial. Some research suggests that oats in themselves are gluten free, but that they are virtually always contaminated by other grains during distribution or processing. However, recent research[20] indicated that a protein naturally found in oats (avenin) possessed peptide sequences closely resembling wheat gluten and caused mucosal inflammation in significant numbers of celiac disease sufferers. Some examination results show that even oats that are not contaminated with wheat particles are nonetheless dangerous, while not very harmful to the majority. Such oats are generally considered risky for celiac children to eat, but two studies show that they are completely safe for celiac adults to eat. People who are merely gluten-sensitive may be able to eat oats without adverse effect,[21] even over a period of five years.[22] Given this conflicting information, excluding oats appears to be the only risk-free practice for celiac disease sufferers of all ages.[23] However, medically approved guidelines exist for those celiacs who do wish to introduce oats into their diet.[24]
Unless manufactured in a dedicated facility and under gluten-free practices, all cereal grains, including oats, can be cross-contaminated with gluten. Grains become contaminated with gluten by sharing the same farm, truck, mill, or bagging facility as wheat and other gluten-containing grains. Therefore, removing all flours and grains from the diet may be the only way to guarantee a complete absence of gluten in the diet.
Standards for "gluten-free" labelling have been set up by the "Codex Alimentarius"; however, these regulations do not apply to "foods which in their normal form do not contain gluten".[25]
The legal definition of the phrase "gluten-free" varies from country to country. Current research suggests that for persons with coeliac disease the maximum safe level of gluten in a finished product is probably less than 0.02% (200 parts per million) and possibly as little as 0.002% (20 parts per million).
Australian standards reserve the "gluten free" label for foods with less than 5 parts per million of gluten, as this is the smallest amount currently detectable. In the processing of gluten-containing grains, gluten is removed (shown in the processing flow below)
Wheat Flour (80,000ppm) > Wheat Starch (200ppm) > Dextrin > Maltodextrin > Glucose Syrup (<5ppm) > Dextrose > Caramel Color
Since ordinary wheat flour contains approximately 12% gluten,[26] even a tiny amount of wheat flour can cross-contaminate a gluten-free product. Therefore, considerable care must be taken to prevent cross-contamination in both commercial and home food preparation.
This diet rules out all ordinary breads, pastas, and many convenience foods; it also excludes gravies, custards, soups and sauces thickened with wheat, rye, barley or other gluten-containing flour. Many countries do not require labeling of gluten containing products, but in several countries (especially Australia and the European Union) new product labeling standards are enforcing the labeling of gluten-containing ingredients. Various gluten-free bakery and pasta products are available from specialty retailers.
In the United States, gluten may not be listed on the labels of certain foods because the U.S. Food and Drug Administration has classified gluten as GRAS (Generally Recognized As Safe).[27] Requirements for proper labeling are being formulated by the USDA. It is currently up to the manufacturers of "gluten free" food items to guarantee such a claim. "A final rule that defines the term gluten-free and identifies the criteria that would enable the food industry to use that term" was scheduled to be released by the FDA on August 2, 2008.[28] This final rule has not yet come to fruition. For now, many individuals who must eat gluten free use sources online to search the gluten free content of products.
Many so-called gluten free products, such as chicken bouillon, corn cereal, and caramel ice cream topping, have been found to have been contaminated with gluten.[29] For example, in an investigation reported by the Chicago Tribune on November 21, 2008, Wellshire Farms chicken nuggets labeled "gluten-free" were purchased and samples were sent to a food allergy lab at the University of Nebraska.[30] Results of the testing indicated gluten was present in levels exceeding 2,000 ppm. After the article was published, the products continued to be sold. However, after receiving customer inquiries, Whole Foods Market removed the product from their shelves over a month later. Wellshire Farms has since replaced the batter used in their chicken nuggets.[31]
In the United Kingdom, only cereals currently need to be labeled, while other products are voluntary.[32] For example, most British sausages contain Butcher's Rusk, a grain-derived food additive.[33] Furthermore, while UK companies selling food prepared on their own premises are given guidance by the Food Standards Agency, they are not required to meet any labeling requirements.[34]
Lastly, some non-foodstuffs such as medications and vitamin supplements, especially those in tablet form, may contain gluten as an excipient or binding agent.[35][36] People with gluten intolerances may therefore require specialist compounding of their medication.[26]
Several celiac groups report that according to the American Dietetic Association's "Manual of Clinical Dietetics"[37][38] many types of alcoholic beverages are considered gluten free, provided no colourings or other additives have been added as these ingredients may contain gluten. Although most forms of whiskey are distilled from a mash that includes grains that contain gluten, distillation removes any proteins present in the mash, including gluten. Although up to 49% of the mash for Bourbon and up to 20% of the mash for corn whiskey may be made up of wheat, or rye, all-corn Bourbons and corn whiskeys do exist, and are generally labeled as such. Spirits made without any grain such as brandy, wine, mead, cider, sherry, port, rum, tequila and vermouth generally do not contain gluten, although some vineyards use a flour paste to caulk the oak barrels in which wine is aged,[39] and other vineyards use gluten as a clarifying agent (though it's unclear whether gluten remains at the end of the clarification process).[40][41] Therefore, some coeliacs may wish to exercise caution. Liqueurs and pre-mixed drinks should be examined carefully for gluten-derived ingredients.
While many spirits were traditionally made without grain, such as tequila, rum and vodka, today they are more commonly made with barley, wheat or rye (instead of agave, sugar or potatoes, et cetera). Often, only high-end specialty alcoholic brands are made with what are considered the traditional ingredients. In addition, many people diagnosed with celiac disease still experience symptoms when drinking distilled alcoholic beverages. Therefore, it is advised that a person with celiac disease check with a manufacturer about the ingredients that have been used in a hard liquor, and to proceed with caution if choosing to drink a liquor that is made with wheat, barley, oats or rye.
Almost all beers are brewed with malted barley or wheat and will contain gluten. Sorghum and buckwheat-based gluten-free beers are available, but remain a niche market. Some low-gluten beers are also available, however there is disagreement over the use of gluten products in brewed beverages: Some brewers argue that the proteins from such grains as barley or wheat are converted into amino acids during the brewing process and are therefore gluten-free;[42] however, there is evidence that this claim is false.[43]
Bread, which is a staple in the Western diet, is typically made from grains such as wheat that contain gluten. Wheat gluten contributes to the elasticity of dough and is thus an important component of bread. Gluten-free bread is made with ground flours from a variety of materials such as almonds, rice (rice bread), sorghum (sorghum bread), corn (cornbread), or legumes like beans (bean bread) , but since these flours lack gluten it can be difficult for them to retain their shape as they rise and they may be less "fluffy". Additives such as xanthum gum, hydroxypropyl methylcellulose (HPMC), corn starch, or eggs are used to compensate for the lack of gluten.[44]
Gluten-free diets (for reasons other than celiac disease) have become a recent trend.[45] Evidence of the diet's efficacy as an autism treatment is poor.[46] Despite vigorous marketing, a variety of studies, including a study by the University of Rochester found that the "Popular Autism Diet Does Not Demonstrate Behavioral Improvement", have failed to support any genuine benefit to children diagnosed with Autism who do not also have a known digestive condition which benefits from a gluten free diet.[47]
Many gluten-free products are not fortified or enriched and contain lower amounts of nutrients such as folate, iron, and fiber than other foods.[48] Additionally, because gluten-free products are not always available, many Gluten-Sensitive Enteropathy (GSE) patients do not consume the recommended number of grain servings per day. A gluten-free diet may not meet the recommended intake for fiber, thiamine, riboflavin, niacin, folate, iron, or calcium. It is important for those who choose to avoid gluten in their diet to find more nutrient-dense food sources to prevent such deficiencies. People who change their standard gluten-free diet to implement gluten-free oats at breakfast, high fiber brown rice bread at lunch, and quinoa as a side at dinner have been found to have significant increases in protein (20.6 g versus 11 g), iron (18.4 mg versus 1.4 mg), calcium (182 mg versus 0 mg), and fiber (12.7 g versus 5 g). The B vitamin group did not have significant increases, but were still found to have improved values of thiamine, riboflavin, niacin, and folate.[49] These dietary changes can greatly reduce a GSE patient's risk for anemia (especially Iron Deficiency Anemia) and low blood calcium levels or poor bone health.
Gluten-free foods include rice, potatoes, soybeans, maize, millet, buckwheat, amaranth and quinoa. The diet may be low in fiber, iron, folate, calcium, magnesium, zinc, vitamin D, B-complex vitamins ( thiamin, riboflavin, niacin, and vitamin B12)[50] Celiacs adhering to a gluten-free diet may be at risk for inadequate calcium, non-starch polysaccharides and Vitamin D. [51] Oats can increase intakes of vitamin B1, magnesium, and zinc in celiac patient in remission. [52]
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