Healthy Diet and Autism: the Science and the Research

August 2, 2021

A great deal of research illustrates why gluten and dairy can cause and contribute to symptoms and the condition of an autism spectrum disorder, and how a gluten-free casein-free (GFCF) diet can help. The underlying factors apply to many other conditions including ADHD, anxiety, neurological conditions, autoimmune conditions, digestive disorders.

Articles by Julie Matthews, NC

Choosing to implement a gluten-free and dairy-free diet for you or your child with autism can be beneficial in many ways. Reports from parents after implementing a gluten-free and dairy-free diet include improvements in areas such as cognition, receptive and expressive language, development, skin conditions, as well as reduction in behaviors, improved sleep, decreased ear infections and digestive symptoms, and more.

If you have heard there is no science behind a gluten-free and dairy-free diet for autism, it’s just not true. Maybe you’ve wondered why you haven’t heard about an autism diet and the science if there’s something to it. Well, this article is for you. Thousands of anecdotal reports from parents plus the existing scientific data shows that following this diet can help children with autism.


1. Opiates from Gluten and Casein in Autism

Did you know that certain long-chain peptides are very similar in structure to natural opioid-binding peptides? Gluten and casein are two such proteins. In fact, gluteomorphin, also known as gliadorphin, is the name of the opiate peptide formed during the (partial) digestion of gluten and casomorphin is the opiate peptide of dairy. These peptides can enter the bloodstream for a few reasons. One of the first reasons is that the body needs adequate enzymes to break down these proteins and specifically an enzyme called DPP-IV. Children with autism have been shown to have lower DPP-IV activity.

Another way these peptides can get into the bloodstream has to do with something that is called “leaky gut.” Leaky gut is a condition where the intestines become permeable, allowing things from the gut into the bloodstream, and leaky gut is common in autism. When that happens, these peptides can bind to opiate receptors in the brain and create a whole range of issues such as high pain tolerance and even feeling foggy or disconnected. Opioids cause inflammation in the gut and brain. They also affect the brain directly, causing many symptoms including pain, irritability, anxiety, foggy thinking, and other symptoms common in autism, as well as addiction to gluten and dairy foods.

2. Zonulin and Its Role in Leaky Gut in Autism

Another advantage of implementing this diet is that gluten is known to trigger zonulin. Zonulin is a protein that modulates the permeability of the GI tract (gastrointestinal tract), and causes it to “unzip” or open, also known as “leaky gut.” Studies show zonulin has been linked to gut permeability in autism, as well as many chronic inflammatory disorders (including autoimmune, metabolic, digestive, cancer, and neuroinflammatory).

An increase in gut permeability can cause heightened reactions to other food components in the intestinal tract for children with autism. This can result in constipation, diarrhea, inflammation, food allergies/intolerances, or trouble concentrating. Since the gut and brain are connected, when the gut is unhealthy, the brain can’t function optimally. … Kids following a gluten-free diet have a much lower intestinal permeability than those who consume gluten.

3. Inflammation to Gluten and Dairy in Autism

IgG antibodies to foods create inflammation in the body and in the gastrointestinal tract. In autism, researchers found high titer IgG antibodies to gliadin (gluten) in 87% of individuals with autism (as well as 86% of of those with schizophrenia) and high IgG antibodies to casein in 90% of people with autism (and 93% of schizophrenic patients). In another study, elevated inflammatory markers (cytokines) to gluten were found in people with ASD (Autism Spectrum Disorder) who had GI symptoms.

Inflammation as a result of gluten and dairy can create issues in the gut and gastrointestinal symptoms such as diarrhea, constipation, gas, and pain. And in turn, this can cause systemic inflammation that affects the brain, as well as the negative effects caused by not breaking down our nutrients properly to get the nutrition our brain and body need.

4. Mast Cell Activation in Autism

Mast cell activation and high histamine levels are common in autism, and research suggests this activation leads to inflammation in the brain (and locally in the gut) and is a possible cause in the development of autism. Food allergies, as well as gluten and casein intolerance, can cause histamine release. High histamine in turn can contribute to gastrointestinal disorders and high acid levels in the stomach and GERD (gastroesophageal reflux disease). And conversely histamine can increase food allergies.Gastrointestinal disorders and high histamine in autism lead to increased symptoms and severity of ASD (autism spectrum disorder).

5. Increased risk of Celiac in ASD

Celiac disease is an autoimmune reaction to gluten, where the body attacks the lining of the digestive system, causing severe digestive symptoms, as well as additional health conditions. While much of what we see in autism is non-celiac gluten intolerance, there is also an increased risk of celiac disease in autism. Research shows that people with ASD are more likely to carry the HLA gene with the HLA-DRB1 *11-DQB1*07 structure, which increases the risks of celiac disease.

6. Gluten, Casein, and the Glutamate Connection

Glutamate is an excitatory neurotransmitter and some children (and adults) with autism are more sensitive, and their brains are more responsive to the effects of glutamate. That can result in more hyperactivity, irritability, restlessness, anxiety, migraines, seizures, and many more symptoms. Recent studies also show that elevated glutamate is often found in people with autism.

Gluten is 25% glutamate by weight, and casein is 20%. Hence, gluten and casein in a diet can increase glutamate levels. And in sensitive people or those with high levels of glutamate such as those with autism, these foods can exacerbate neurological symptoms, including irritability, stress, anxiety, and hyperactivity. Glutamate can also cause inflammation in the brain and gastrointestinal system. Limiting the intake of gluten and casein in a diet can help reduce symptoms related to autism.

7. Dairy and Cerebral Folate Deficiency

Some children with autism have a condition known as Cerebral Folate Deficiency. In this condition, folate is not able to be transported properly into the brain because of autoantibodies to the folate receptor, and there are not adequate levels of folate in the brain. This can lead to irritability and sleep problems, low muscle tone, slow head growth, loss of bodily movement, speech complications, and seizures.

One study showed that 75.3% of children with autism had folate receptor autoantibodies. Studies show that soluble folate-binding proteins in milk can cross react with folate receptors, increasing autoantibodies to folate receptors making this problem even worse for kids with autism by further decreasing folate to the brain. Conversely, studies show a dairy-free diet can reduce folate receptor autoimmunity in cerebral folate deficiency syndrome. A milk-free diet decreases folate receptor antibodies and autoimmunity.


Above I’ve shared the underlying factors that cause gluten and dairy to be a problem for people with autism. Below I share the growing scientific literature on the efficacy and benefits of a gluten-free and dairy-free diet.

91% of Children with Autism Improved Behavior, Speech, and/or GI on GFCFSF

Research suggests that ASD may be accompanied by inflammatory immune responses, and that this may predispose people with autism to be more sensitive to the protein in wheat, dairy, and soy. Sensitization to these dietary proteins then leads to inflammation of the digestive system and exacerbates negative behaviors.

This exciting study resulted in 91% of the children showing clinical improvement that was observed by therapists/teachers/parents following implementation of a casein-free, gluten-free, and/or soy-free (cf/gf/sf) diet. Improvements were seen in GI symptoms, speech, autistic behavior, less hyperactivity, better focusing, and improved night time sleep.

4.5x Developmental Age and 6.7 pts IQ from Diet and Nutrition Intervention in Autism

This is a study I am particularly proud of because I was a part of it. Our study showed a 4.5x increase in developmental age as well as a 6.7 pts increase in non-verbal IQ. The study involved individuals aged 3-58 years old implementing a dietary intervention of a healthy gluten-free, casein-free, and soy-free diet; along with a multivitamin/mineral formula, essential fatty acid supplement, digestive enzymes, and a couple of additional nutritional interventions studied over one year.

In addition to improvements in development and IQ, major areas of improvement where seen across the board in included a reduction in autism symptoms and GI symptoms, improvement in language, focus, anxiety, and more.

Reduced Autism Behaviors, Increased Social and Communication Skills with GFCF Diet

This report reviewed existing scientific literature and found consistently positive results with a GFCF diet for autism. The literature included papers where groups of children were studied, as well as individual case studies. Researchers found there was an overall reduction of autism behaviors, increased social skills, and communicative skills. They also noted that autism traits reappeared after the diet had been broken.

Development Was Significantly Better For the ASD Group On a GFCF Diet

The aim of this study was to evaluate the effect of a gluten and casein-free diet for children with autism and on urinary opioid peptides associated with gluten, gliadin, and casein. The study found that the children who were on a gluten-free and dairy-free diet had better development than the controls. Given the prevalence of impaired social interaction, communication, and imaginative skills in autism, this study shows how powerful dietary changes can be!

Significant Improvement in Autism and ADHD (Attention Deficit Hyperactivity Disorder) Symptoms in Children with ASD on the GFCF Diet

This study was a two-stage, 24-month, randomised, controlled trial with 72 Danish children (aged 4 years to 10 years 11 months) assigned to diet (A) or non-diet (B) groups. Autism Diagnostic Observation Schedule (ADOS) and the Gilliam Autism Rating Scale (GARS) were used to assess core autism behaviours, Vineland Adaptive Behaviour Scales (VABS) to ascertain developmental level, and Attention-Deficit Hyperactivity Disorder – IV scale (ADHD-IV) to determine inattention and hyperactivity. At 12 months, there was a significant improvement to the diet group scores on all autism, behavior, and ADHD scales measured. Because of the improvement in group A, group B was also assigned to the diet midway through the trial. The results suggest that dietary intervention may positively affect developmental outcomes for children diagnosed with ASD.

GFCF and Keto Diets Improve Autism Symptoms

One study compared the GFCF diet to the Ketogenic diet for autism. Both diet groups had significant improvement in autism symptoms. There were some differences – one diet showed better results in behavior, while the other diet group had better scores for cognitive awareness and sociability. In summary, the results of this study showed that they are both good diets to improve symptoms of autism, depending on the individual needs of the person. And this study highlights another example of how the GFCF diet can benefit individuals with autism.

Following a gluten-free and casein-free (GFCF) diet can help alleviate autism symptoms. Creating an autism diet plan in advance can help you implement a GFCF diet smoothly and successfully. Making these adjustments to your child’s diet can improve their symptoms of autism while also offering additional health benefits. The encouraging news is that dietary intervention for autism can be an effective way to make dramatic improvements in your child’s health, learning, and behavior.

Full Articles by Julie Matthews, NC and Scientific References for these Articles

Julie Matthews is a Certified Nutrition Consultant and Educator, nutrition expert, published researcher, and award-winning author. Her guidance is backed by twenty years of clinical experience and scientific research with complex neurological and physiological needs; particularly autism and related disorders.