Gluten-free diet has no effect on autism, according to a new study

Parents of autistic children are constantly seeking new treatments. Autism spectrum disorder, or ASD, is a developmental disorder that causes problems in social interaction and communication, ranging from mild to severe. It's an extremely challenging condition for parents, and as of today there is no cure.

However, there are plenty of websites that offer treatments for autism, many of them unproven. One of the more common claims is that autistic children will benefit from a gluten-free, casein-free diet. There has been some weakly supportive evidence for this idea, such as this 2012 report from Penn State, but that study was based entirely on interviews with parents. Interviews are notoriously unreliable for scientific data collection.

Perhaps because so few effective treatments are available, many parents of autistic children have tried gluten-free diets, in the hope that perhaps they might work. (One can find entire books dedicated to this diet.)

The science behind the idea that gluten or casein causes (or worsens) autism has always been sketchy. The push for diet-based treatments has its origins in the anti-vaccine movement, beginning with the fraudulent 1998 study (eventually retracted) in The Lancet led by Andrew Wakefield, a former gastroenterologist who lost his medical license after his fraud was discovered. Wakefield claimed that autism was caused by a "leaky gut," which somehow allowed vaccine particles to make their way to the brain, which in turn caused autism. That chain of events was never supported by scientific evidence. Nonetheless, it morphed into the hypothesis that gluten (or casein) somehow leaks out of the intestines and causes some symptoms of autism. There's no evidence to support that either.

(Despite losing his medical license, Wakefield has become a leading voice in the anti-vaccine movement, making speeches and even movies to try to convince parents not to vaccinate their kids. Many journalists and scientists have written about him and the harm that he's done, but that's not my topic today.)

Another hypothesis, according to WebMD, is that autistic children have some kind of allergic reaction to gluten. There is no good evidence for this either.

Surprisingly, virtually no good studies have asked the question, do gluten-containing foods actually cause the symptoms of autism? Now we have a carefully-done study that provides an answer.

The new study, just published in the Journal of Autism and Developmental Disorders, is the first randomized, well-controlled study of gluten-free diets in children with autism. The scientists, all from the University of Warsaw, Poland, recruited 66 children, and assigned half of them at random to a gluten-free diet. The other half were given a normal diet, with at least one meal a day containing gluten, for 6 months. The children ranged from 3 to 5 years old. After 6 months, the scientists evaluated all children using multiple standardized measurements of autistic behavior.

The results were very clear: the study found no difference between the diets. None of the core symptoms of ASD were different between children in the two groups, and there were no differences in gastrointestinal symptoms either. As the study itself stated:

"There is no evidence either against or in favor of gluten avoidance for managing symptoms of ASD in children." 

This study should put to rest all of the claims that a gluten-free diet can somehow improve the symptoms of autism. It doesn't provide an easy answer for parents, and the medical community still needs to do much more work to find better treatments. But let's hope that parents get the message: don't feed your autistic child a restricted diet.