Does food affect autism? Though still a controversial topic, one thing I can definitely say is, “Yes, food affects autism.” How do I know this? It's simple. (Post may contain affiliate links)


A healthy, balanced diet that is complete with all of the essential vitamins, minerals, fiber and good quality ingredients will make anyone feel better.

BUT Does Food Affect Autism?

Autism is traditionally viewed as a neurodevelopmental disorder. However, a large percentage of persons diagnosed also have digestive problems. Despite this, traditional treatments focus on controlling behavior through psychiatric and social therapies.  These therapies are important in the overall treatment plan. But what has been largely ignored by the medical field is the role of diet in treating autism (and ADHD).

Research shows that the role of digestive disorders in the development of autism needs to be taken more seriously. Common digestive issues are constipation, diarrhea, and intolerance to milk products (casein) and gluten. And as many as 50% of children put on a gluten-free/casein-free diet (GF/CF) improve. Not only that, but other therapies, including supplementation, are shown to improve behavioral problems.

What follows is a brief summary showing the relationship between symptoms and nutritional status.

Raising Adventurous Kids

Different Diet Considerations

Dysfunction of the digestive system is more common in children with autism than in children without autism. Part of these dysfunctions can be explained by a lack of the enzymes required to properly digest certain carbohydrates and proteins. This helps to explain why many children respond well to a GF/CF diet. Gluten is the protein in certain grains and casein is the protein in cow's milk products.

Click here for help with GF/CF diet (Free download).

Some children have problems digesting certain types of carbohydrates as well. This is one of the reasons why so many different diets have been proposed. For example, the ketogenic diet, which is extremely low in carbohydrates, and the specific carbohydrate diet (SCD), which limits certain carbohydrates. Also, a low oxalate diet is sometimes proposed.

The Ketogenic Diet

The main issue with putting your children on any of these diets is the potential for nutritional deficiencies. For example, the ketogenic diet (90% fat, low protein, low carbohydrate) is extremely low in fiber and high in saturated fat. So there is a risk of cardiovascular complications and constipation (which is often already a problem). The Ketogenic diet has been shown to be effective in about 25% of children, and is a good option to consider IF YOUR CHILD HAS PROBLEMS WITH SEIZURES. The Ketogenic diet has been used to treat epilepsy for decades, though it is not effective for everyone. However, it is a highly restrictive diet and should not be followed without the guidance of a physician and a dietitian.

Here is an example of what a ketogenic diet might look like.

Specific Carbohydrate Diet (SCD)

This diet recommends limiting carbohydrates to monosaccharides, which are one molecule sugars. The rationale behind this idea is that polysaccharides (“poly” means “many) are harder to digest and contribute to digestive problems.

The logic goes something like this: “When foods aren't digested properly, sometimes there is “intestinal overgrowth” which leads to disease-causing bacteria in the gut.”

This diet is extremely restrictive, and in my opinion, not a diet that should be followed long-term. It may however, help with short term healing of the inflamed gut during acute flare-ups. But except for testimonials, the research is sorely lacking.

An example of what a SCD diet might look like is here.

Low Oxalate Diet

This diet is based on the possibility that high oxalate levels in the blood contribute to the symptoms of Autism. So, on this diet, foods rich in oxalates are avoided. For example, spinach, beetroots, cocoa, black tea, figs, lemon zest, and a whole slew of other foods.

Here is what a low-oxalate diet looks like.

Nutritional Status of Child with Autism

The reason supplementation is usually helpful is because a large percentage of children are deficient due to inadequate intake and poor absorption of nutrients.

Omega-3 Fatty Acids

Omega-3 fatty acids are extremely important to the proper development of the nervous system in children. This starts in the womb and is why it is important that pregnant moms are getting enough omega-3s in their diet. Breastmilk contains the essential omega-3s which previously were lacking in formula. In approximately 1999, the FDA approved omega-3s to be added to formulas because there was so much evidence showing their benefits.

As children grow, omega-3s continue to be important. However, seafood is one of the top allergens. Plus people in the US usually don't consume enough fish to meet needs. Thus, supplementation is usually necessary to see a difference. And there is strong evidence that supplementing with omega-3 fatty acids in kids with autism, aged 5-17, results in improvements in speech and articulation, openness to social interaction, as well as improved mental health.

In contrast, a deficiency of omega-3s results in loss of concentration, hyperactivity, dyslexia, dyspraxia, and the symptoms of autism. In other words, sometimes a contributing cause to the development of ADHD, autism, and other developmental delays is an omega-3 deficiency.

Vitamin B6 and Magnesium

Vitamin B6 is vital in the synthesis of neurotransmitters. For example, serotonin, dopamine, norepinephrine and epinephrine. These are the neurotransmitters that are targeted when MDs prescribe medications to treat depression and sometimes ADHD. Persons with Autism Spectrum Disorder (ASD) are also affected.

Research involving blood levels of vitamin B6 shows interesting results. Whereas blood levels of B6 are often high in persons with autism, the enzymes necessary to make the vitamin active, and thus useful to the body, are often low. This means that even if the child is consuming enough vitamin B6 through diet, it is possible that the B6 is not available for his body to use.

Research supports that vitamin B6 and magnesium supplementation improves behavior in persons with autism. Speak to your doctor if you are concerned about your child's B6 or magnesium status.

But you can start by working to assure that adequate amounts of both of these important nutrients are in your family's diet. One big step is encouraging whole grains, nuts and seeds as much as possible. Also, magnesium is rich in all green vegetables.

Vitamin C

Vitamin C is an antioxidant and may have a protective effect. However, more research is needed in order to determine if vitamin supplementation is necessary. It is really not that hard to get enough vitamin C. One 8 ounce glass of Orange Juice, for example, has 120% of the US RDA of vitamin C. Broccoli, cauliflower, zucchini, tomatoes, pineapple and mango are all good sources as well. Click here for a list of foods high in vitamin C.

Vitamin A

If your child is deficient in vitamin A, supplementation may be helpful. However, vitamin A can be toxic in high doses. So I don't recommend supplementation  except as part of a multivitamin supplement. Most multivitamins contain vitamin A.

Vitamin D

Inadequate Vitamin D intake has been linked to increased risk for autism. This was discussed elsewhere. It has also been shown to have a “neuro-protective” effect, and may be important to proper action of neurotransmitters as well.

Vitamin B12 and Folic Acid

Deficiencies in the Cerebrospinal fluid (CSF) have been seen in patients with ASD. This appears to be related to autoantibodies that bind receptors necessary for folate use by the body. As a result, even though folate is high in the blood, it is not available to the body for use. Both B12 and folate are important for a healthy nervous system. So, it is important to make sure there is adequate intake of both vitamins. B12 is found in all animal products and fortified cereals and nondairy milks. Folate is rich in green vegetables and orange juice.


Children with autism and other sensory processing issues often limit food intake. Thus, iron deficiency is a common problem. However, due to the common digestive problems associated with autism (and ADHD), often the iron deficiency is related to poor absorption. The first step to preventing iron-deficiency is assuring your child is getting iron rich foods every day. You can increase the absorption by combining vitamin C rich foods with iron rich foods. See here for a list of food combinations that increase iron absorption.

Also, if you are concerned, have your child's iron levels tested. If they are low, your doctor may suggest a supplement.

Keep in mind that a multivitamin with iron will not usually contribute to constipation problems. However, high dosage iron supplements often do lead to constipation. Your doctor will help you weigh the benefits and the risks.

Zinc and Copper

The relationship between zinc and copper is confusing and complicated. Suffice it to say that both zinc and copper can be low in children with autism, but it is a fine line between too little and too much. Zinc affects copper status and vice versa. So, it's important to keep them in balance. This is where a Registered Dietitian who specializes in treating autism with supplements can greatly help.

Click here for a quick summary and sample menus for each of the three diets mentioned above. (Ketogenic, SCD, and Low Oxalate).

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