Treating autism spectrum disorder with gluten-free and casein-free diet: the underlying microbiota-gut-brain axis mechanisms

There is a rising interest in the use of dietary interventions to
ameliorate prevalent brain diseases, including Autism Spectrum
Disorder (ASD). Nowadays, the existence of communication between
gut and brain is well accepted and thus diet can influence
brain functioning. A well-known nutrition based intervention for ASD
is the gluten-free and casein-free diet. However, only some of the
patients experience a relief in symptoms and thus efficacy seems to
be limited to certain phenotypes. However, not much is known about
the mechanism of action through which this diet might work, or about
interpersonal differences that could lead to variation in response to
the diet. Current evidence for efficacy of the GFCF diet is poor. Large
scale, good quality randomized controlled trials are needed. Genetic
and environmentally induced interpersonal differences were found in
intestinal membrane permeability and blood brain barrier integrity as
well as in activity of peptidase enzymes. These differences probably
affect responsiveness to the diet. In addition, age and duration of the
dietary intervention play a role in the efficacy of the gluten-free and
casein-free diet. This is the reason why all these factors need to be
taken into account to give appropriate advice about whether or not to
follow this diet.