Gluten is a wheat protein that adversely affects people with celiac disease or who have gluten intolerance. Those with celiac disease do not digest gluten properly, and various side effects occur when they eat gluten. Meat, fruits, vegetables and grains such as corn, quinoa, rice, amaranth and buckwheat are all naturally gluten free; however, foods naturally gluten free that are processed in a plant with gluten foods may be cross contaminated.
Wheat
Wheat is the major, obvious source of gluten. Anything that contains wheat or a by-product such as wheat flour contains gluten. Products such as pasta, bread, cereal, cake or cookies normally contain gluten. Wheat flour can be used as a thickener in certain foods, so read all ingredients on packaged foods to avoid gluten. Other unexpected wheat gluten sources are soy sauce and the meat alternative, seitan. Seitan is derived from wheat protein and, therefore, contains gluten.
Barley
Barley is another source of gluten, and therefore, it should be avoided by those with gluten intolerance. Barley is a grain that is also used as a base for making malt flavoring, beer and caramel coloring. Salads, soups or stews may also contain barley, so check food ingredients before eating these foods.
Rye
Rye contains gluten protein. Foods such as pumpernickel and rye bread are common sources for rye flour. Rye is not as common as wheat and barley, but it is included as part of the most common three sources of gluten. Gluten-free breads are becoming more prevalent, and even gluten-free rye bread may be available certain places.
Cross-Contamination
Many foods prepared in food processing plants may be a source for gluten contamination. Labels will state if the food is made in a processing plant that may be a source of gluten. Oats are gluten free, but because of how they are processed can contain gluten.
