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Gluten-Free Casein-Free Diet for Autism – Where’s the Science?

AMY GARDNER / May 24, 2018

Does the gluten-free casein-free (GFCF) diet improve autism symptoms? Many parents say yes. But what does the science say?

Important note: Autism presents as a highly complex disorder with many possible etiologies and current treatment approaches are directed at symptom management. Autism presents differently from one individual to the next and likewise, treatment must be customized.

80% of parents of children with autism report using some type of dietary intervention. 29% report using the gluten-free casein-free (GFCF) diet. When parents were asked about the effects of the diet, 10-29% reported significant improvement in autism spectrum core dimensions (language, social, behavior).
(Lang, KW et al 2015)

Some individuals with autism may not fully breakdown proteins in wheat (gluten and gliadin) and milk (casein) demonstrated by urinary peptide abnormalities commonly found (Reichert et al 1981; Israngkun et al 1986; Reichelt et al 1990; Knivsberg et al 1990, 1995, 1998, 1999; Rimland 1988, 2000; Lucarelli et al 1995; Shattock et al 1995; Adams & Conn et al 1997; Cade et al 1999; Whitely et al 1999). The observed abnormalities suggest the proteins are broken down and absorbed as peptides (3 amino acid units) instead of single amino acids. These peptides, caseinomorphine and gluteomorphine, as the names suggest, appear to have opioid-like effects in the body. They have been found in urine, serum and spinal fluid of autism patients. In rats, these opioids cross the blood-brain barrier, impacting the central nervous (CNS) and inhibit CNS maturation (Sun et al 1999).

The question is then raised – would removing these proteins from the diet enhance learning in those with autism?  A number of studies
indicate this could be the case. However, they have been criticized for methodological flaws. Studies are either very small (1-15 participants),
short in duration (4 days to 3 months), demonstrate null or mixed results or long (12 months or more) but fail to account for other possible explanations for improved symptoms.

One single-blind controlled study looking at children with both autism and urinary peptide abnormalities in 10 children ages 5-10 demonstrated significantly greater improvement in measurements of attention, communication, sensory/motor and cognitive factors in those following the GFCF diet for 12 months compared to the control group. (Knivsberg AM et al, 2002). The authors suggest improvement in attention contributed to improvement in other domains.
There is no indication as to how these children were recruited (i.e. were they in the same school system?) and other treatment interventions
that may have occurred during this time period were not controlled for. While there does appear to be some correlation between the GFCF diet and improvement in autism domains for those with urinary peptide abnormalities, more research is needed.

recent double-blind study demonstrated no improvements in autistic domains with GFCF diet. (Hyman et al 2015). This study included 14 kids age 3-5 years and did not limit it to those with confirmed urinary peptide abnormalities. The kids were split into 2 groups (experimental and control group). For the first 4-6 weeks, all kids were placed on GFCF diet. During the following 12 weeks, both groups continued on the GFCF diet. Weekly snack challenges were deliverd that contained gluten, casein, gluten and casein, or placebo. The foods looked the same. Parents and researchers did not know which food participants received.
Parents were asked to track autistic symptoms, bowel patterns, sleep and behavior. No differences were found between groups after exposure to either gluten or casein or both proteins together.   There are clear limitations in this study as well.  How strictly did the parents adhere
to the GFCF diet?  Could it be that a weekly exposure to gluten and/or casein doesn’t contribute to increased symptoms but that more
regular exposure would?

Gastrointestinal issues are very common in children with autism. Interestingly, the reported incidence of GI disorders in children with autism ranges from 9-90% in research studies. Talk about a wide range of variability!  Children on the spectrum can present very differently. As such, it’s essential to individualize our treatment approaches.
And equally important to continually evaluate and adjust treatment approaches.

The gut plays an important role in neurological health. Perhaps instead of, or along with a GFCF diet, we look at strategies to heal the gut, the
long-term goal serving to liberalize the diet as much as possible. And while a GFCF diet could be a helpful component for some children, it’s
most certainly not for everyone.

So, the answer my friends, is that the verdict’s still out. Preliminary research and anecdotal evidence suggest there could be benefit to the GFCF diet. And, thanks to the plethora of gluten-free options and milk alternatives, we can do it safely, providing adequate nutrition for growth. However, this is not a “one size fits all” solution and many factors must be considered not least of which is preserving a healthy feeding dynamic. If you would like to explore a GFCF diet for your child, please seek guidance from an experienced registered dietitian who understands the complexity of autism.