People with autism often have problems with their digestive organs like the stomach or gut. These problems could be inflammations, abdominal pain, gas, diarrhea or bacterial overgrowth. The reasons may be malnutrition, food intolerances or allergies. Specific food products causing these problems are left out from the diet. In many cases, products containing gluten or casein, the main protein occurring in dairy products, are excluded. In many cases vitamins, minerals as well as essential fatty acids are additionally provided. A big problem is that many autistic people cannot tell that they have pain. Because of this, many problems concerning the digestive organs are not noticed.