Researchers at The University of Texas Health Science Center at Houston have begun a double-blind clinical study to look into the question.

"There's a lot of misinformation, so that's why this study is so important," lead investigator Dr. Fernando Navarro said in a statement. "Hundreds and hundreds of parents think this works but we need serious evidence."

Researchers are enrolling 38 autistic children ages 3 to 9, who will be taken off gluten -- a protein in wheat -- and dairy products before the four-week study. Half will then be given gluten/milk powder and half will be given a placebo powder.

Casomorphin, a peptide in milk, and gliadomorphin, a peptide in gluten, are thought to affect behavior in these children, Navarro said.

"A lot of children with autism have gastrointestinal problems such as constipation and diarrhea," co-investigator Katherine Loveland said. "There are neurotransmitters and neuroreceptors in the gut that correspond with those in the brain. There are some scientific reasons to think that some kids may benefit from this diet."