One of the first connections made between diet and mental illness or deficit was made by Curtis Dohan in the 1960s. Dr. Dothan found that the guts of schizophrenics were particularly permeable and digested wheat and dairy proteins inefficiently. He then reported that native people in the South Pacific who had low levels of wheat and dairy in their diets also had low levels of schizophrenia in the population.
In 1979 Dr. Jaak Panksepp reported observing a similar association between this type of diet and autism. This theory was expanded in 1991 when Dr. Kalle Reichelt observed that autistic children had peptides (which are the products of protein breakdown) in their urine which were not found in the urine of non-autistic children. These urinary peptides were suspected as having arisen from the incomplete breakdown of the proteins gluten and casein. Scientists suspected that these peptides can cross the blood-brain barrier of autistic individuals and may be toxic and have an opioid effect on the brain and has become known as the ‘Opioid Excess Theory.’ (This should not be confused with a gluten or casein allergy, because rather than acting as allergens these compounds actually act as toxins.)
Opioids are naturally occurring compounds released during times of stress and help us manage pain and discomfort. For example, distance runners may experience a ‘runner’s high’ during which pain is lessened and a feeling of euphoria can begin. This phenomenon is attributable to the release of opioids. These compounds are similar to opiates, which are substances that originate from the poppy plant and which are used in powerful painkilling drugs such as morphine and heroin. While opiates and opioids have different origins, the effects are similar.
The Opioid Excess theory states that the urinary peptides unique to autistic individuals may in fact act as excessive opioids, an effect that would mimic an opiate addiction. For instance, one of the symptoms of autism is self-injurious behavior, which may seem less painful when excess opioids are present.
Several years after Dr. Reichelt’s research, these opioids were identified as glidaorphin and casomorphine which are derived from gluten and casein proteins, respectively. This discovery led to the theory that eliminating gluten (in the form of wheat products) and casein (from milk products) in the diet may be able to reduce or eliminate the levels of circulating opioids, which spawned the belief that a gluten-free casein-free (GFCF) diet can lessen symptoms of autism.
While the research on the correlation between a GFCF diet and lessening the severity of autism symptoms has burgeoned recently, most of the evidence of such an association remains anecdotal and not backed by sound science. Currently, however, strides are being made by researchers in the field including Mr. Paul Shattock and colleagues at the Autism Research Unit at University of Sunderland. Visiting their website (http://centres.sunderland.ac.uk/autism/) is a good way to keep apprised of the newest areas of research with all aspects of autism, including those relating to the potential benefits of a GFCF diet.