Autism Spectrum Disorder Diets


Autism Spectrum Disorder Diets

Many people with many different medical conditions have gastrointestinal symptoms. One condition that people may not associated with gastrointestinal (GI) symptoms is Autism Spectrum Disorder (ASD). ASD is a developmental disorder that encompasses a deficit in social interaction, communication, and repetitive stereotyped behavior, interest, and activities. Standard treatment is a broad-based strategy. New evidence shows that certain diets may help improve some of the GI symptoms found in ASD patients.

Autism Spectrum Disorder Overview

Autism, as stated above, is a neurodevelopmental disorder characterized by difficulties processing social interactions and communication. Scientists believe it is partly genetic in nature and partly caused by environmental factors. There are inflammatory and immune factors that are associated with individuals with autism but have not been named necessarily as the cause.

Every person with ASD is unique since it is a spectrum disorder. As a spectrum disorder, people can have varying severity of symptoms. They all have certain commonalities. However, hallmarks include impaired social interaction and repetitive stereotyped behavior or interest. Social impairment includes reduced eye contact, reduced language skills, difficulty communicating, and difficulty understanding and communicating emotions. Stereotyped,
repetitive behavior includes things like hand-wringing, clapping, and arms flapping. Stereotyped interests and activities could include an overly avid interest in a very specific subject, like certain modes of transportation.

ASD and GI Symptoms

GI symptoms are a common complaint in people with ASD. Symptoms include constipation or diarrhea, or difficulty eating certain foods. Researchers have found that people with autism have changes in both the gastrointestinal microbiome, the bacteria in their gut. They have also found that people with ASD have increased permeability compared to neurotypical people. Increased intestinal permeability means that these patients may have issues digesting carbohydrates and absorbing other nutrients. Gluten-free, casein-free diets, pre- and probiotics, and multivitamin supplementation have been tried in scientific studies.

ASD Experimental Diets

As stated above, there are a number of experimental diets that scientists have tried in order to improve GI symptoms. Some major diets include a Gluten-free diet, casein-free diet, and probiotics. Each one will be explored in detail below. With gluten and casein, scientists believe that the increased permeability of the intestines causes the proteins to be inadequately absorbed and metabolized, causing GI symptoms. Researchers also hypothesize that these proteins may cause some behavioral symptoms as well.

Gluten- and Casein-free Diets

Gluten is a protein found in wheat products. It acts as a glue that holds starches together. Some people, like those with Celiac Disease, cannot tolerate gluten due to changes in their intestinal lining. This results in malabsorption, which causes diarrhea, weight loss, fatigue, and often malnutrition. Casein is a protein found in wheat similar in structure to gluten. While it is not associated with a specific disease like Celiac Disease, researchers hypothesized that it might behave similarly to gluten in people with ASD because it has a similar molecularly structure.

Studies found that about 13% of children with ASD in 18 European countries were on a gluten-free or casein-free diet. Between 41 and 69% of parents reported that those children had positive effects from the diets. Another study in the UK found that of the children with ASD on gluten-free and casein-free diets, 20-29% stated that their children had significant improvement in core ASD domains. They also endorsed improvement in specific symptoms. For example, 54% had significant improvement in GI symptoms, 42% had significant improvement in concentration, 29% in communication, and 25% in social interaction.

Some scientists point to flaws in these studies. One major flaw is that these are surveys sent to parents. Surveys are notoriously vulnerable to methodology flaws because they rely on people’s memory and subjective feelings. Another major issue is that there is no control group in many studies. A control group serves as a comparison to the group being studied. Without this comparison, researchers cannot adequately compare whether or not the interventions just
affected people with ASD or would affect everyone similarly.


Patients with ASD have a microbiome that is different from neurotypical patients. Their symptoms are quite similar to those with Inflammatory Bowel Disease and Irritable Bowel Syndrome. Researchers hypothesized that because probiotics helped people with those conditions, they might also help people with ASD. Multiple probiotic studies in children with ASD found improvement in behavioral and GI symptoms. In one double-blinded cross-over study, the parents who were on probiotics refused to switch to become control subjects without probiotics but the probiotics helped their children so much.


ASD is a complicated disorder to manage. Many patients have had success using gluten-free diets, casein-free diets, and probiotics as one arm of their management strategy. While many critics argue that these studies are not the most scientifically sound due to the nature of the spectrum, still many find that these interventions are relatively cheap, easy, and effective. Contact the Stem Cell Transplant Institute to learn more about ASD today.

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