Many people are allergic to wheat.
Corn Corn allergies are also very common. People allergic to corn must avoid corn in all of its forms. These include cornmeal, polenta, maltodextrose, dextrose, corn oil, fructose and corn syrup. Gluten People allergic to gluten often have a disease called gluten-sensitive enteropathy or celiac disease. Gluten is a grain protein that is found at high levels in wheat and in smaller amounts in rye, oats, barley, triticale, spelt and kamut.