A diet popular as an alternative treatment for autism doesn’t appear to improve behaviors or symptoms of the condition, according to a small but rigorously conducted study published this month in the Journal of Autism and Developmental Disorders.

The new work, conducted by researchers at the University of Rochester Medical Center, examines the gluten-free, casein-free diet and offers what many experts in the field say perhaps the highest-quality evidence to date that eliminating proteins found in wheat and dairy doesn’t improve autism symptoms.

Many interventions for autism have been well-studied and demonstrate benefits, particularly if begun in children very young, including applied behavior analysis and developmental therapies.

But many families are willing to try a range of unproven therapies in an effort to do whatever they can to help their children, say clinicians and advocates. Some in the autism community have long suspected that diet and food additives have a negative impact on children with the developmental disorder, which is characterized by social and communication deficits.

Anecdotal reports about restrictive diets improving or even erasing symptoms in children have prompted many parents to try such diets—especially, over the past 15 years or so, those restricting gluten, a protein found in wheat, and casein, present in dairy. At the University of Rochester’s Kirch Developmental Services Center, where some 1,200 children with autism are seen a year, about 1/3 have been on such a diet at some point, according to Susan Hyman, division chief of neurodevelopmental and behavioral pediatrics there and the lead author of the newly published paper.

One theory behind the gluten- and casein-free diet is that children with autism have trouble digesting these proteins and, because of a “leaky gut”, absorb components of these compounds that lead to physical discomfort and behavioral symptoms, according to Dr. Hyman.

Research evidence about the diet, however, has been sparse and mixed. One major limitation of previous work is that usually parents know that the child is on the diet, leading to potential bias.

Experts’ biggest worry about the diet is that children may not get all necessary nutrients, such as calcium and vitamin D, once major food groups are eliminated. The diet also can be difficult for the parents to administer and the child to endure, particularly since many with autism tend to be picky eaters.

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