Oats do not contain gluten because it isn't related to wheat, barley or rye. They are safe to eat for most people with celiac disease, which is a condition that causes an allergy to gluten. Some patients with celiac disease also have an allergy to avenins, which oats do contain.
Many people with celiac disease must purchase special brands of oats that are not processed on the same equipment as products that contain gluten. Because of the extra fiber in oats, some people with celiac disease experience GI symptoms because of the extra amount of fiber they receive. For those with celiac disease who want to consume oats but don't want to risk an allergic reaction, Bob's Red Mill and GF Harvest produce products that are 100 percent gluten-free.