How common are gastrointestinal disorders in children with autism?

We could identify no report that describes the prevalence of gastrointestinal disorders in a representative group of children with a diagnosis of autism compared with appropriate controls. Thus, we found no evidence upon which to base a confident conclusion as to whether gastrointestinal symptoms are more common in children with than without autism. However, the frequency of gastrointestinal symptoms observed in population-based samples of autistic children indicate that gastrointestinal problems are not nearly as common in children with autism as reports from pediatric gastroenterology clinics suggest.