Gluten, which is the substance used to bind dough in many baked foods, may cause severe reactions in some people. Once diagnosed, a gluten-free diet is required to prevent damage to the intestines. Wheat, barley and rye contain gluten, as do many additives made from these products and included in many common foods, including some cheese. More series ailments, like celiac disease, can be diagnosed with a biopsy or blood test. You must understand that negative results from these tests do not mean you don't have gluten intolerance.