Many people have difficulty digesting gluten and casein proteins commonly found in foods, resulting in discomforts like gas and bloating. Gluten is the main protein complex primarily found in grains including wheat, barley, spelt and rye. It may also be present in medications, processed foods, soaps and cosmetics. Casein is found in dairy products and processed foods. Even those on gluten-free/casein-free diets may experience difficulties due to cross-contamination from offending foods.