This study reviewed the removal of casein and gluten from the diet of autistic people, the main measures of the Sunderland Protocol, a document guiding biomedical actions aimed at treating autism. The justification for the study is based on the scarcity of studies on the subject and the wide-ranging debate on the efficacy of casein- and gluten-free diets in the treatment of autism spectrum disorder. The aim was to carry out a literature search on the scientific basis of removing casein and gluten from the diet of patients with autism spectrum disorder and to expose other adjuvant actions present in the protocol in order to verify the possibility of reducing the symptoms of the disorder. This is the first study in a series of three works that seek treatment and raise consistent hypotheses about the origins of the disorder.