A gluten-free diet is a diet completely free of gluten. Gluten is a protein found in wheat (including kamut and spelt), barley, rye, malts and triticale. Gluten is also used as a food additive in the form of a flavoring, stabilizing or thickening agent, often hidden under "maltodextrine", "dextrine", and "dextrose". A gluten-free diet is the only medically accepted treatment for celiac disease, the related condition dermatitis herpetiformis, and wheat allergy.
Accuracy of "gluten-free" labels
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, 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). 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 . 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. One common gluten free product search site is Celiaccess.com 
any so-called gluten free products have been found to have been contaminated with gluten such as chicken bouillon, corn cereal, and caramel ice cream topping. . 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. 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.
In the United Kingdom, only cereals currently need to be labeled, while other products are voluntary. For example, most British sausages contain Butcher’s Rusk, a grain-derivedfood additive. 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.
Lastly, some non-foodstuffs such as medications and vitamin supplements, especially those in tablet form, may contain gluten as an excipient or binding agent. People with gluten intolerances may therefore require specialist compounding of their medication.
Several celiac groups report that according to the American Dietetic Association‘s "Manual of Clinical Dietetics"  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, and other vineyards use gluten as a clarifying agent (though it’s unclear whether gluten remains at the end of the clarification process). 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
The scientific literature on the link between gluten and autism is mixed and there is no substantial research on in utero causality. There have been too few adequately designed, large-scale controlled studies and clinical trials to state whether the diet is effective. A small, single-blind study has documented fewer autistic behaviors in children fed a gluten-free, casein-free diet, but noted no change in cognitive skills, linguistic ability, or motor ability. This study has been criticized for its small sample size, singleblind design which may have skewed results on the basis of a "parent placebo effect". A 2006 double-blind short-term study found no significant differences in behavior between children on a gluten-free, casein-free diet and those on regular diets. A long term double-blind clinical trial sponsored by the National Institute of Mental Health ran from 2004 until November 2008; as of July 2009, results are not yet available.
Gluten sensitivity is also seen as a genetically inheritable problem. With gluten being an ingredient in medication it is highly advised that a person on the gluten free diet consult a doctor and check the labels of medications before beginning a medication.
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 coeliac 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 Redbridge beer buckwheat-based gluten-free beers are available, but remain very much a specialty product. 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, however there is evidence that this claim is false.