Gluten intolerance, also called non-celiac gluten sensitivity, is another food intolerance that causes GI symptoms. With this, you have difficulty digesting gluten, the protein in wheat, rye, and barley. Gluten intolerance is different from celiac disease, in which the body’s reaction to gluten damages the lining of the small intestine. Gluten intolerance causes bloating, gas, and other digestive symptoms. Some people also report migraines and difficulty concentrating after eating gluten. Food intolerances like this are fairly common and can involve a wide range of foods. With a food intolerance, you might be able to eat small amounts of the offending food without symptoms. That’s different from an allergy, where even a small bite will trigger a reaction.