FAB RESEARCH COMMENT:
This review examines the evidence from animal models that some symptoms of schizophrenia and related conditions (including autism, ADHD) may reflect a sensitivity to opioid peptides derived from the normal digestion of either gluten or A1 beta-casein (the form of casein found in standard cows' milk, but not other mammal milks).
These opioid peptides (gliadomorphin, and beta-casomorphin-7, or BCM-7) activate the same opioid receptors as morphine. However, they would only be expected to produce behavioural effects if both the gut lining and the blood-brain barrier are unusually permeable.
So-called 'Opioid theories' of both autism and schizophrenia have led to the proposal that gluten-free and casein-free diets may help to alleviate symptoms. Case studies and clinical reports have provided some evidence that such diets might be of benefit in some individual cases, but further research is still needed.
Psychiatric diagnoses like schizophrenia and autism are purely descriptive, and conceal huge individual variability in both symptoms and probable causes. It therefore seems a priori unlikely that this kind of dietary intervention would help more than a subset of patients.
However, given the severity of these conditions and the relative safety of dietary approaches, clinicians would do well to explore the possibiliy that unusual reactivity to gluten and/or casein might contribute to symptoms of schizophrenia, autism or related conditions.
And see also FAB factsheet: