There's no evidence that special diets are an effective treatment for autism, now called autism spectrum disorder.
Autism spectrum disorder is a complex brain disorder that has no known cure. For this reason, many frustrated parents turn to unproven alternative treatments — such as restrictive diets that eliminate gluten and casein — in an attempt to help their children.
Gluten is a protein found in many grains, and casein is a protein found in dairy products. However, there's little evidence that diet triggers autism spectrum disorder or that restricting gluten and casein improves symptoms. And for growing children, restrictive diets can lead to nutritional deficiencies.
If you're considering an alternative treatment for autism spectrum disorder, including diets, talk to your child's doctor. He or she can help you understand possible benefits and risks. Ask your doctor about resources that provide evidence-based information or offer support. If you decide to pursue a restrictive diet, work with a registered dietitian to create an appropriate meal plan for your child.