Autism and autism spectrum disorders (ASD) are a group of conditions that cause difficulties with social learning, communication and language. Children or affected adults also sometimes exhibit sensory hypersensitivity as well as signs of repetitive behavior. Some individuals also experience constipation and/or chronic diarrhea. The cause of autism has been the subject of many investigations in recent years but has not yet been established by the scientific community. More and more international studies, however, show a correlation between ASD and impaired neurological function, defective immune system and unbalanced intestinal flora. Few conventional therapy options are available for people with autism spectrum disorders and are usually based only on adapted learning methods or modified diets.