Gluten and casein
People who have joint pain and are sensitive to gluten, found in wheat, barley and rye, or casein, found in dairy products, may find relief by avoiding them. And those diagnosed with celiac disease, in which gluten sets off an autoimmune response that damages the small intestine and sometimes causes joint pain may find relief when they adopt a gluten-free diet. There may be an overlap in which some people with arthritis also have gluten sensitivity or also have celiac disease.