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Autism Diets: Fundamental for Health and Optimal Potential

Article provided by: Julie Matthews

The road to autism recovery begins with diet. That is, choosing foods to add and remove from the diet is the first step to improving the health and well-being of children with autism. Certain food substances (most notably, gluten and casein, the principal proteins in wheat and cow’s milk, respectively) are known to be problematic for many children with autismand other foods, rich in healing nutrients, may be beneficial. Attention to these factors can help balance biochemistry, effect systemic healing, and provide relief of autism symptoms.


Historically, autism was considered a “mysterious” brain disorder, implying that it began and ended in the brain. In recent years, a more appropriate “whole body disorder” perspective of autism has emerged, reflecting the fact that the brain is affected by the biochemistry of the body. Martha Herbert, MD, PhD, one of the first to describe autism in this way, refers to the brain as “downstream” from the body.

Common physical symptoms of children with autism include diarrhea, constipation, bloating and gastrointestinal (GI) pain, frequent infections, sleeping challenges, and inflammation/pain.[ii] The fact that there are physical as well as behavioral symptoms illustrates that autism is not solely a brain disorder. When we appropriately identify autism as a whole body disorder, we can comprehend how what happens inside the body and cells affects the brain—and how the food we feed a child affects the body and its biochemistry.

For many children with autism, factors such as nutrient deficiencies, imbalanced biochemistry, and digestive problems can play a significant role in causing or exacerbating symptoms. Altering food choices can affect physiological functioning and help improve symptoms—both physical and behavioral.


A healthy diet and good digestion are essential for good health. For many children, the physiological and behavioral symptoms of autism may stem from or be aggravated by impaired digestion and GI health. One research study concluded that “unrecognized gastrointestinal disorders...may contribute to the behavioral problems of the non-verbal autistic patients.”[iii]

Poor digestion can lead to a condition known as leaky gut (increased intestinal permeability), which can result in malabsorption of nutrients, inflammatory responses to foods that are not broken down, and overload of the detoxification system. Adequate nutritional status, essential to proper biochemical and brain functions, requires both the consumption of nutrient-dense foods and proper digestion to break down and absorb those foods.

Impaired digestion often stems from negative environmental factors (as well as genetic susceptibility), lack of beneficial bacteria, inflammation, and immune system response to certain foods; and studies have shown leaky gut,[iv] low levels of beneficial flora,[v] inflammation, and immune response to food[vi] [vii] in children with autism. Additionally, the response to certain foods, such as gluten and casein, can create an opiate or inflammatory reaction that can affect the brain.

Thus the gut is an essential component to understand and address in autism. The largest part of the immune system is found in the gut—and the immune system is often imbalanced in autism, causing an inability to fight viruses, yeast, and other pathogens properly, while contributing an overactive inflammatory and allergic response. Toxins originating in the gut, often from “bad” (pathogenic) bacteria and yeast, can affect the brain. Foods that are not digested properly can create inflammatory and immune system responses affecting the brain. Ninety percent of the brain chemical serotonin is found in the gut and has a profound effect on the gut/brain connection and regulating gut motility and pain sensitivity.

According to Hippocrates, “All disease begins in the gut,” and this certainly proves true with autism. In fact, the gut was coined “the second brain” by Michael Gershon, MD, who spent many years studying the gut-brain connection. Derrick MacFabe, MD, identified this gut-brain connection in autism, in his recent study on propionic acid, a fatty acid that originates in the gut; he found that, in rats, propionic acid caused behavioral and biochemical symptoms similar to those found in autism.[viii]


Below are more details on how imbalanced digestion and biochemistry can cause or exacerbate autism symptoms, along with practical ways to support digestion and biochemistry through diet and nutrition, and thus to help improve symptoms.

Yeast overgrowth: Yeast is a harmful organism that can affect energy level, clarity of thought, and intestinal health. It is often triggered by heavy antibiotic use—common in children with autism, who tend to have poor bacteria-fighting ability. Yeast overgrowth creates gut inflammation and decreases gut function. When there is yeast overgrowth in the GI tract, toxins enter the bloodstream and make their way to the brain, where they can cause symptoms including spaciness, foggy thinking, and drunken behavior.[ix] Supportive actions can include removing sugars and yeast-containing foods from the diet, reducing or removing refined starches, and adding probiotic-rich foods.

Poor methylation and sulfation: Methylation, transsulfuration, and sulfation are just one set of biochemical pathways that do not function optimally for many children with autism. These pathways lead to the production of glutathione and other substances used for detoxification, immune function, gut integrity, and antioxidant status. In addition, methylation is required for properly activating neurotransmitters, and when not working properly, neurotransmitters cannot function as needed, increasing the likelihood of anxiety, depression, ADHD, and sleeping issues.[x] These biochemical pathways can be supported by avoiding certain substances that are processed by them and can overburden them, and by supplying needed nutrients. For those with decreased methylation and sulfation, it can be helpful to remove phenolic foods and foods high in salicylates, amines, and glutamates. Also, improve methylation and sulfation through supplementation. These supplements typically include B12, B6, folate, and others.

Gut inflammation: Improving digestion, reducing inflammation, and healing the gut are important steps in overall health and healing. Commonly reported benefits include reduced diarrhea and constipation, improved behavior, greater language skills, and fewer skin rashes. Inflammation in the gut and brain can be caused by toxins, food sensitivities, or bad bacteria or yeast in the gut. This can cause pain, which affects behavior—for example, self-injurious behavior, such as leaning over furniture, eye poking, or head banging, can be a sign of pain.iii To address inflammation, remove foods that inflame the gut, such as gluten, casein, and soy; add foods that heal the gut and are anti-inflammatory, such as antioxidant-rich fruits and vegetables; add foods that supply beneficial bacteria (probiotics), such as non-dairy yogurt and raw sauerkraut; and add foods that support beneficial bacteria growth (prebiotics) such as raw dandelion greens, garlic and onions.

Poor detoxification: When children’s detoxification systems are not working optimally, as is common with autism,[xi] toxins from food and the environment—such as salicylates, artificial food ingredients, monosodium glutamate (MSG), mercury, and aluminum—can cross the blood-brain barrier and affect the brain, causing hyperactivity, aggression, irritability, and self-injurious behavior.[xii] Thus, it is important to avoid additional toxins and promote detoxification: avoid food additives; avoid toxins in the food supply and in meal preparation; serve organic foods; and add foods that support the liver such as sulfur-rich foods including cruciferous vegetables and eggs, beets, grass-fed liver, and probiotic-containing lacto-fermentations.

Nutrient deficiencies: When digestion is poor and the gut is too permeable, nutrients are not absorbed properly. This leads to nutrient deficiencies, which can negatively affect all cellular function, including brain function. Nutrient deficiencies are common among children with autism,[xiii][xiv][xv] and poor quality and limited diets exacerbate this problem. Specific nutrients are required for complex biochemical processes, and nutrients can only be digested and absorbed from food and supplementation when the GI tract is functioning well. In addition to providing a wide variety of nutrients through foods, supporting digestion is important, and supplementation including B6, magnesium and vitamin C has shown to be supportive.[xvi][xvii] Measures to address nutrient deficiencies can include increasing the quality and digestibility of food, sneaking in vegetables for children who are picky eaters, juicing vegetables, preparing homemade bone broths, and adding appropriate supplementation.

I hope that parents and practitioners can see the possibilities for positive influence and realize that diet can help autism. Diet is a powerful personal tool; it has few downsides and is accessible to everyone. With diet, parents have great control over choices that can have immediate positive impact in the health of their children.


The most successful parents (and children) in my private practice are those that take steps to carefully implement autism diets. They believe that recovery is possible and that, through calculated food choices, they can make a difference. While modern medical channels present few options, parents are following Hippocrates’ traditional advice and letting food be their medicine.
There are many autism diets to choose from, and deciding how to begin nutritional intervention can seem overwhelming. Ten years ago, it was a simpler choice—“do diet!” And, “do diet” meant do the gluten-free casein-free diet (GFCF). Eliminating gluten and casein was the primary focus of diet for autism for many years, and these interventions have proven to be very beneficial. Since then, additional advances in biomedical nutrition research and mom-centric anecdotal data have resulted in broader dietary strategies for autism.

Now, one has to decide which diet to apply. Because every child is different, a diet that helps one child may not be the best for another. Each child has unique biochemistry, immune functioning, genes, environment assaults, and eating preferences.

In my book, Nourishing Hope for Autism, I discuss thirteen different diets that are recommended for autism. While each diet has merit, some include advanced components that are best supported by an experienced practitioner and not necessarily required to get started. In this article, I will explain the top three diets for autism—these include the most immediately helpful dietary principles and practices, and there is much literature and community support to aid their successful implementation.


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