Analysis says gluten- and casein-free diets may not affect behavior in autistic patients

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Gluten-free and casein-free diets may not work as effectively as a standardized treatment for children diagnosed with an autism-spectrum disorder, according to new research by the University of Granada in Spain and published in the Journal of Autism and Developmental Disorders.

For the study, researchers analyzed the effects of a gluten-free diet and a casein-free diet on the behavior of children diagnosed with autism-spectrum disorders. They reviewed two studies and a sample of 65 children.

The first study was a pilot clinical assay carried out on 28 children and adolescents diagnosed with autism-spectrum disorders who followed a gluten-free diet for three months and then switched to a casein-free diet for three months. The second study included 37 children and adolescents diagnosed with autism-spectrum disorders. Participants followed one of the two diets for six months, then the other diet for six months. The study included variables relating to the efficacy, risk, and safety of following the diets.

Given the limitations of attempts to treat such disorders, many families turn to alternative therapies. Among these, gluten-free and casein-free diets implemented as a therapeutic approach in autism-spectrum disorders have been the subject of significant interest and controversy in scholarly research. Some authors have found such diets to have favorable effects on the symptoms of autism, while more recent studies have found no conclusive results.

The researchers in the current analysis found no significant changes either in the behavioral scales or in the beta-casomorphin levels in urine after the subjects had followed the gluten-free and the casein-free diet.

Beta-casomorphin is a peptide formed in the intestine due to abnormal digestion of cow's milk protein or casein. People with autism-spectrum disorders may present an abnormal porosity in the intestinal barrier that enables beta-casomorphin to penetrate the barrier, enter the blood circulation, and reach the central nervous system, producing a toxic effect, according to researchers.

Some scientists have identified peptiduria, the abnormal presence of peptides in the urine, in children with autism-spectrum disorders and detected a reduction of these peptides in subjects who have followed the gluten-free and casein-free diet. Researchers from the current analysis said it may be that autism cases with associated gastrointestinal disorders may benefit from such an approach.

Researchers said future studies would include include placebo and double-blind elements, as well as other biological markers to better define the subjects who may benefit from these diets.