According to Dr. Daniel Coury, medical director of the Autism Treatment Network, about 20 percent of parents within the Autism Treatment Network use complementary methods to treat their autistic child, and more than half of those use some form of diets.
"Clearly the gluten free diet is successful in those with celiac disease, but there is no consistent pattern in children with autism," said Coury.
According to Hines, many parents of autistic children hear about diets so often through the autism community that, regardless of the lack of evidence, they are compelled to try it.
"I do caution that the [GFCF] diet can lack in calcium and protein so I suggest [that parents] meet with a nutritionist," said Hines. "If the diet has helped you, then do what you need to do, but really there's nothing supporting any recommendation to use it for children with autism."
While Marshall said she did not see the value in the diet for her son's autism, many parents like herself are likely to try treatments they've been told worked for other autistic children.
"I've been there; you want to try anything and everything for your kid to make sure you've done your best, so I can understand people wanting to give it a try," said Marshall. "But I don't think you should put all your eggs in one basket. It is not a cure for autism."
According to Coury although many children in general suffer from gastrointestinal problems, children with autism are less likely to be treated than those without the disorder.
"Some physicians assume that GI complaints are part in parcel with the child having autism, and so they say nothing can be done," said Coury. "But if those complaints are with a typical child, then proper medical attention is sought."
The same treatment that is offered to children without autism who suffer from GI issues should be given to those with autism, he said. For some autistic children in some instances, spontaneous movements may be a reaction to gastrointestinal pain.
"We might miss that with children on the spectrum because we attribute these behaviors to autism rather than GI reflux," said Coury.
"We know that gastrointestinal symptoms exist across the entire pediatric population," said Hines. "When some of these non-verbal autistic children have pain, they may not be able to tell you what is experienced among all children."
But while current research does not suggest a link between autism and bowel disease, according to Coury, improving the GI problems could help improve an autistic child's overall health.
"If we improve your health, and you feel better, you're more available to learn in school, you're more available to make improvement in your development," said Coury. "So we think improvement in health may help the child make better progress in their autism."