Gluten-free and casein-free diets in the management of autism spectrum disorder: A systematic literature review

Abstract

Autism spectrum disorder (ASD) comprises a group of heterogeneous constellations characterized by deficits
in cognitive, communicative, and social skills. ASD has no established etiology and the search for reliable biomarkers
has proved to be difficult, giving rise to alternative theoretical accounts, including those related to nutrition. One such
account posits that the proteins gluten and casein, derived from wheat and milk respectively, are causally involved in
the symptomatic expression of the disorder. As a consequence, a diet devoid of such proteins has been hypothesized
to ameliorate the behavioral symptoms of children with ASD. The scope of the present review is to analyze the effects
of gluten-free and casein-free (GFCF) diets on children with autism. It has been shown that 8‒32% of parents of affected
children report the current use of a GFCF diet regimen in their children. The majority of identified dietary intervention
studies failed to meet basic methodological standards of interventional science. A comparison of studies conducted
with adequate scientific rigor did not show any clear-cut results. In addition to the inconsistent pattern of results,
findings of challenge studies largely failed to find behavioral effects after applying gluten/casein challenges to children
with ASD. Studies of potential side effects suggest that it is important to monitor both aspects of nutritional adequacy
and healthy physical development in children with ASD on a GFCF dietary regimen. In conclusion, evidence for the
effectiveness of the GFCF diet in the treatment of autism is sparse. Rigorous scientific evaluations found no convincing
evidence of therapeutic effects of the GFCF diet. Nevertheless, more sophisticated investigations should be conducted
in order to identify possible benefits and harms of such a dietary approach, particularly in subgroups of individuals with
ASD yet to be identified.