Autism experts descended upon Parliament Hill Thursday, calling for more research to be conducted into the possible link between a specialized diet and the developmental disability.

Many parents have reported anecdotal evidence suggesting that a dairy and gluten-free diet may reduce the symptoms of autism.

Fannie Decaria says at one point her son, Guilio could hardly speak. Then she cut wheat protein and dairy out of his diet and she saw improvement within days.

"I swear, within a week my son started to speak more," she told CTV News.

Actress Jenny McCarthy wrote a book discussing the success she's having in feeding her autistic son a diet free of gluten, wheat and dairy products.

Critics say stories such as McCarthy's amount to nothing more than anecdotal evidence, and aren't backed by any credible scientific evidence. But some experts took their message to Parliament Hill on Thursday, arguing that autism is a public health crisis that deserves more study.

"I think what we are looking at is a transition from a behaviour disorder and brain disorder to a whole body condition," Dr. Martha Herbert of the Harvard Medical School told a press conference.

Herbert and some experts say it's time to conduct scientific research into finding out if there's something more to the anecdotal evidence. They want more money to study the link between processes in the gastro-intestinal system and behaviour.

It's research that Derek McFabe of the University of Western Ontario has already started. He says that his studies of rats suggest that there may be an indirect link between some food and autism.

Officials with Autism Canada say that with an increasing number of children are diagnosed with autism,  studying diet and the disease is crucial.

Researchers hope that more research will give parents of autistic children more information to decide if they should switch their child's diet.

McCarthy said she noticed that her son's eye contact and vocabulary noticeably improved within weeks as a result of being on the wheat and gluten-free diet. The children's cartoon "SpongeBob SquarePants" did not usually connect with her son Evan, but when he laughed at something "very abstract and funny" while watching it, McCarthy said she knew it was important.

"That was my big moment ... I call it kind of opening the window and pulling him out of the world of autism," McCarthy told CTV's Canada AM.

With a report from CTV's Genevieve Beauchemin