Wheat, rye and barley contain a protein called gluten. People with celiac disease cannot tolerate gluten as it injures the lining of their small intestine. Totally eliminating gluten from the diet gives the lining a chance to heal. However, a gluten-free diet is not easy. Gluten sources may not always be obvious from the names on food labels.
Grains from wheat, rye and barley top the list of forbidden ingredients on a gluten-free diet. Additional forbidden grain and grain products include bulgar, a cereal made from wheat, couscous, durum wheat, pastas, semolina, spelt and triticale, a genetically modified grain made by crossing wheat and rye grains. Flavored and instant coffees may also be made with wheat.
Oats do not contain gluten. Early evidence suggested that oats caused problems for people on gluten-free diets, but further investigation revealed that the problems were due to the fact that the oats had been processed in machines that had also processed wheat, a practice no longer very common.
Forbidden foods also include processed products made from wheat, rye and barley, such as breads, buns, crackers, cereals, pretzels, pastries, pizza and pasta, to name just a few.
Stabilizers and Starches
Many ingredients contain grain products not obvious by the name on the label. Starches and stabilizers often contain wheat-based ingredients, and unless specifically labeled as not derived from wheat, they would be forbidden to those on a gluten-free diet. Stabilizers, starches, flavorings, emulsifiers, hydrolyzed proteins could all contain gluten. Modified food starch contains gluten unless derived from arrowroot, corn, potato, tapioca or maize.
Vegetable gum contains gluten. There are vegetable gums that do not contain gluten, such as those from carob bean, locust bean, cellulose, guar, gum arabic, gum aracia, gum tragacanth, xantham or vegetable starch. However, products listing vegetable gum without stating its source are assumed to contain gluten, and are therefore forbidden. Similarly, unless indicated to the contrary, soy sauce and soy sauce solids are derived from wheat and contain gluten. Because of differences in labeling laws in different countries, certain imported foods labeled "gluten-free" could still contain wheat starch, and would be forbidden.
Drinks and drink mixes, including hot cocoa mixes and chocolate milk mixes may contain hidden sources of gluten from the malted barley used to make these products. Malted milk shakes contain gluten, as do malted beers, ales, lagers and stouts. Similarly, other milk-based processed foods could contain malted barley products, including processed cheeses, puddings, ice creams and frozen yogurts.
Meats and Meat Substitutes
Any meat or fish dish prepared with bread crumbs made from wheat, rye, barley or other forbidden grain would be forbidden. Some meat substitutes, such as canned baked beans, include gluten stabilizers. Any deli meat, cold cut, hot dog or roast listing processed vegetable protein or hydrolyzed vegetable protein contains gluten and would be forbidden. Similarly, pasta products made from wheat, barley, rye or other forbidden flours, as well as imitation seafood and imitation bacon products containing gluten stabilizers, would also be forbidden.
Fruits and Vegetables
While vegetables themselves do not contain gluten, processed vegetables could. Jarred baby foods, such as pureed vegetables, for example, may contain added starch which contains gluten. Creamed or breaded vegetables could contain gluten. Any canned vegetable product containing a starch or stabilizer contains gluten unless it specifically indicates that the source of that starch is gluten-free. Fruit jams, jellies, spreads, sauces and syrups may contain thickeners which are often starch-based and contain gluten. While mustard seeds are gluten-free, prepared mustards may contain flour, beer or malt vinegar, which do contain gluten.
Snacks and Desserts
Cakes, cookies, doughnuts and pastries made from flour contain gluten. Ice-cream cones, pie crusts, cookie mixes, cake mixes and bread puddings all contain gluten. Similarly, pretzels, flavored potato chips and some French fries also contain flours made from forbidden grains and therefore contain gluten. Fruit pies without the crust could also contain gluten from the thickener used to gel the fruit. Similarly, licorice and jelly beans often contain gluten in the form of modified starch and stabilizers.
Soups, Sauces and Seasonings
Any soups, sauces or gravies thickened with wheat flour or gluten-containing grains would be forbidden, as well as all soups containing barley, pasta or other noodles made from the forbidden grains. Synthetic pepper, brewer's yeast and yeast extract contain barley, unless specifically prepared with a sugar molasses base. Malt vinegar often used to flavor fish or prepare certain salad dressing contains gluten due to the use of malted barley. Seasoning mixes may contain gluten, as could chili sauce and steak sauces. They often contain modified food starches or stabilizers which contain gluten.
Personal Care Products
Nonfood sources of gluten that could be problematic to people on a gluten-free diet include lipsticks and lip balms, medications, play dough and toothpaste. Vitamins use gluten as a binding agent, as does toothpaste. Mouthwash may also contain stabilizers and preservatives containing gluten.