An expert panel says there's no strong evidence that digestive problems are more common in children with autism, compared with other children, or that special diets work, contrary to claims by celebrities and vaccine naysayers.

Painful digestive problems can trigger problem behaviour in children with autism and should be treated by a doctor, according to the panel's report published in the January issue of Pediatrics and released Monday.

'I think we still have a lot to learn about the gut and how it contributes to behavioural symptoms.'— Lee Grossman

"There are a lot of barriers to medical care to children with autism," said the report's lead author, Dr. Timothy Buie of Harvard Medical School.

"They can be destructive and unruly in the office, or they can't sit still. The nature of their condition often prevents them from getting standard medical care."

Some pediatricians' offices "can't handle those kids," Buie said, especially if children are in pain or discomfort because of bloating or stomach cramps. Pain can set off problem behaviour, further complicating diagnosis, especially if the child has trouble communicating.

Autism is a spectrum of disorders affecting a person's ability to communicate and interact with others. Children with autism may make poor eye contact or exhibit repetitive movements such as rocking or hand-flapping.

About one in 110 U.S. children have autism, according to a recent government estimate. A 2006 study suggested one in 165 Canadian children had the disorder.

More than 25 experts met in Boston in 2008 to write the consensus report after reviewing medical research. The Autism Society and other autism groups funded the effort, but gave no input.

The report rejects the controversial idea that there's a digestive problem specific to autism called "leaky gut" or "autistic enterocolitis."

The hypothesis was first floated in 1998 in a now-discredited study by British physician Dr. Andrew Wakefield. His paper tied a particular type of autism and bowel disease to the measles vaccine.

The new report says the existence of autistic enterocolitis "has not been established." Buie said researchers and doctors have avoided digestive issues in autism because of their connection with Wakefield's disputed research, which set off a backlash against vaccines that continues to this day.

The new report calls for more rigorous research into the prevalence of digestive problems and whether special diets might help some children.

Watch for nutritional deficiency

For now, the report states, available information doesn't support special diets for autism.

Diets have been promoted by actress Jenny McCarthy, whose bestseller Louder Than Words detailed her search for treatments for her autistic son.

Nearly one in five children with autism are on a special diet, according to a project that tracks what treatments parents are trying. Most of them were on diets that eliminate gluten, found in many grains, or casein, a protein in milk, or both, according to the Interactive Autism Network at the Kennedy Krieger Institute in Baltimore, Md.

The new report advises doctors to watch for nutritional deficiencies in patients with autism. It recommends a nutritionist get involved if a patient is on a special diet or only eats certain foods.

The report drew praise from Rebecca Estepp of Poway, Calif., who believes a special diet is helping her autistic son. She said the paper gives pediatricians credible recommendations they've needed.

"I'm filled with hope after reading this report," said Estepp, a member of the support group Talk About Curing Autism. "I wish this report would have come out 10 years ago when my son was diagnosed."

Lee Grossman, president of the Autism Society, a funder, said many doctors have written off autistic children's digestive problems as untreatable.

"I think we still have a lot to learn about the gut and how it contributes to behavioural symptoms," Grossman said. "We have a lot to learn about how to treat this."

Buie said his clinic has various techniques for treating children with problem behaviour. They schedule early-morning appointments so children aren't delayed in the waiting room or blow bubbles during a blood draw as a distraction.

As a last resort, they use anesthesia.

"If a child is going to be asleep because of a dental evaluation or an MRI study, we will do our endoscopy, our blood work, spinal tap, haircuts or teeth cleaning at the same time," Buie said. "Our nurses do beautiful haircuts."