Currently, there is insufficient evidence to support instituting a gluten-free diet as a treatment for autism.
Perhaps the most commonly cited alternative therapy approach for autism is the gluten free/casein free diet. The idea was promoted largely based on the “leaky gut” and “opiod excess” idea of autism. The basic idea was that the intestines of autistics are for some reason “leaky” and incompletely digested proteins from gluten (grains) and casein (milk) enter the bloodstream and act much like an opiod (drug) causing (somehow) autism. Multiple research teams have looked for evidence of these “opiods” without success. But the idea that eliminating gluten and/or casein as an autism treatment.
Timothy Buie is perhaps one of the most respected gastroenterologists in the autism communities. He has recently written a literature review on the topic:The relationship of autism and gluten.
Here is the abstract: