Many parents of children with autism choose to restrict their child's diet to eliminate Gluten (wheat protein) and Casein (milk protein). Claims have also been made that once a child has been put on this restrictive diet, their autism has been "cured", so is there any truth to this?

Well, first, let me state that unlike other "alternative treatments" for autism, if the parent ensures that the child still gets adequate nutrition, restricting gluten or casein from the diet (as far as I know) does not cause any significant risk or harm to the child. But does it help?

The jury is still out. To my knowledge, there have only been two controlled studies investigating the effect of this type of diet on children with autism. The first was a small study that did find fewer "autistic behaviors" in children on the gluten and casein free diet, however, one major criticism of this study was that it was only a single blind study, meaning the parents knew whether their children were on the GFCF diet or not, and this information may have influenced their reports. Another more recent study that was double blind found no significant difference between the group with the GFCF diet and another group without this diet.