Excerpt from “Psychological Considerations in Food Allergy” Chapter in Food Allergy (4th ed), Blackwell Science, in press:
Childhood autism is characterized by significant abnormal or impaired development in social interaction and communication, and restricted repertoire of activity and interests . Immunologic abnormalities, gluten sensitivity, and food allergy have been proposed to play a role in the pathogenesis and management of autism [2-4]. However, evidence supporting the beneficial effects of dietary manipulation on behavior and cognition in children with autism spectrum disorder have consisted mainly of anecdotal reports and small trials.
Bidet and colleagues  reported increased basophil degranulation to food allergens in 10 autistic children and Lucarelli  reported improvement in behavioral disturbance in 36 autistic children placed on a cow’s milk elimination diet More recently, two small trials examined the benefit of gluten and casein free diets in autistic children. One trial  reported reduction in autistic traits but equivocal results on cognitive skills, and on linguistic and motor ability. The trial by Knivsberg  studied 10 autistic children over one year and reported improvement in the children on the gluten and casein free diets.
Other studies by Sponheim , Renzoni,  and Pavone  were unable to demonstrate improvement in behavior with a gluten free diet, or any association between autism and food allergy or celiac disease. Studies by Walker-Smith  and McCarthy  failed to demonstrate an increased prevalence of celiac disease in autistic patients using antigliadin assays and jejunal biopsies.
Lymphocytic infiltration in the upper and lower GI tract , immune activation , and abnormal lymphocytic responses to dietary antigens  have also been recently reported in children with autism, but the relevance of these findings to cognitive function or to development of autism is still unclear.
These studies demonstrate the need for large scale quality controlled trials in this area. Given the lack of hard evidence supporting the benefits of dietary manipulation in preventing or treating autistic patients, implementation of rigorous elimination diets should be undertaken with great caution. Such unproven measures may divert the autistic patient’s family from more useful treatments and contribute to poor nutrition and further social isolation in families already facing great difficulties.
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