Can a Change in Diet Influence Autism Spectrum Disorder Symptoms?

A change in diet may help, but you’ll have to figure out which approach is best.

Posted Oct 28, 2020

The idea that a special diet will help a child with autism spectrum disorder (ASD) does have some scientific backing from small studies. It may take some experimentation and you’ll have to be especially careful to make sure your child is getting enough nutrients. 

The big picture: Research increasingly connects our gut microbiomes to mental health. Also, about half of people with ASD have gastrointestinal problems. GI symptoms are also common in the general population, but there’s evidence that the frequency of GI symptoms in people with ASD matches up with the severity of ASD symptoms. For example in an analysis of 960 children, those with frequent bouts of abdominal pain, diarrhea, constipation, or gaseousness scored worse on social withdrawal, repetitive behaviors, irritability, and hyperactivity as measured by a well-known test, the Aberrant Behaviors Checklist. Even if your child didn’t have ASD, it would be worth putting effort into seeing whether you can relieve digestive symptoms by cutting out certain foods.

Is your child hard to feed? As their parents know well, children with ASD can be especially picky eaters. In a 2013 meta-analysis of studies to that point, researchers found that children with ASD are five times more likely to have tantrums at meals, engage in eating rituals, and reject food. They’re more likely to be malnourished, with shortages of calcium and protein in particular. 

The two most popular special diets for children with ASD require major changes in the standard U.S. diet. While parents often report that restrictive diets help, the diets can make it harder to keep your child well-nourished.

Gluten-free, Casein-free Diet. Early research with rats found that too much casomorphin, a morphine-like peptide fragment of milk casein, induced social isolation and apathy. One theory was that ASD was triggered when those peptides, released from casein and also gluten, cross a damaged intestinal lining and reach the central nervous system, affecting brain function. Some researchers have identified morphine-like compounds in the urine of people with autism and other neuropsychiatric disorders. However, more specific testing does not support the idea that they are related to gluten or casein.

A handful of small studies have tested whether children with ASD do better without eating casein and gluten. For example, in a randomized trial in Iran with 80 children, 54 percent had GI issues and a gluten-free diet improved both the GI symptoms and behavioral problems. In a randomized, controlled yearlong study in Arizona, researchers compared 67 children and adults with ASD to 50 controls. The ASD volunteers took a special vitamin/mineral supplement, and then received essential fatty acids, Epsom salt baths, carnitine, and digestive enzymes before they went on a gluten-free, casein-free, soy-free diet. The researchers reported improvements in IQ and autism symptoms from the diet and other interventions.

Ketogenic diet. Low-carb Atkins-like diets produce ketones, a kind of fuel your liver produces when you’re low on glucose. Ketogenic diets have been helpful for epilepsy in children and have seemed promising enough to test on ASD volunteers. In one six-month study in Egypt, 45 children aged 3-8 were equally divided into three groups. One ate the ketogenic diet, and another a gluten-free, casein-free diet; the third were the controls. At the end of six months, both diet groups showed improvement on autism symptoms compared to the controls. But the ketogenic group did a bit better.

Should your child take supplements? Nutrients in food are easier to absorb than nutrients from vitamin and mineral supplements. If a child is on a special diet, has a poor appetite, and isn’t growing normally, you might speak to your pediatrician about nutritional supplements.

Overall, the evidence to date doesn’t suggest that every child with ASD should be on one diet or another. You might experiment with diet alongside other therapies. If nothing else, minimizing abdominal pain and other GI symptoms will make your child more comfortable.

A version of this story appears at Your Care Everywhere.