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Autism Spectrum Disorders: Current Research on the Role of Diet and Nutrition

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The incidence of Autism Spectrum Disorders (ASDs) in the United States continues to skyrocket, and is currently estimated to be 1 in 88 American children (and 1 in 54 boys). While the cause has still not been identified, current evidence points to a combination of genetic predisposition combined with environmental triggers.  Emerging data has identified the existence of medical conditions such as alterations in the gastrointestinal, immune, detoxification, and energy generating systems in children on the spectrum. In the recent issue of the supplement to the journal Pediatrics, called “Improving Health Care for Children and Youth With Autism and Other Neurodevelopmental Disorders”, the American Academy of Pediatrics has acknowledged “Many individuals with ASDs have symptoms of associated medical conditions, including seizures, sleep problems, metabolic conditions, and gastrointestinal disorders, which have significant health, developmental, social, and educational impacts.”  Whether these abnormalities are the cause or a consequence of autism remains to be determined, but in each case nutrition plays a critical role.

Autism has been called a gut disorder by some, and parents commonly report that their ASD children experience gastrointestinal (GI) problems at a greater rate than unaffected siblings.The most common presentations include chronic abdominal pain, constipation, and/or diarrhea and symptoms of gastro-esophageal reflux. These symptoms are often apparent from infancy, before the diagnosis of autism has ever been made, reinforcing the theory that underlying medical issues contribute to the development of autism.  Digestive disorders may well be underreported since nonverbal children are not easily able to communicate pain. Self- injurious behaviors such as head banging and the application of pressure on the abdomen are nonverbal cues that discomfort is present. Sleep disturbance has also been reported at a higher rate in autistic children with GI distress. Many pediatricians have considered the digestive component as simply a “part of autism” and have not treated the underlying gastrointestinal abnormalities. In 2010 the journal Pediatrics published a supplemental article entitled “Recommendations for Evaluation and Treatment of Common Gastrointestinal Problems in Children with ASDs”.  The position of the panel of gastroenterologists who authored the article was that children with ASDs should be evaluated for GI disorders as thoroughly as non-ASD children who present with the same symptoms. In addition, the panel stated that “Pediatricians and other primary care providers [should] be alert to potential nutritional problems in patients with ASDs. Evaluation by a nutritionist who is familiar with nutrition support for individuals with ASDs is recommended if caregivers raise concern about the patient’s diet or if the patient exhibits selectivity of intake or is on a restricted diet.” Parents and caregivers who believe their child is suffering from GI problems should also be firm in demanding a thorough evaluation for their child.   

Nutritional deficiencies have been identified in patients with ASD, and are likely a result of a combination of self-limited food choices, malabsorption, and restricted diets. The panel also recommended steps be taken to identify potential associations between food allergens and gastrointestinal problems and called for further research into the existence of intestinal permeability and the effectiveness of gluten and casein free diets. Parents report that a gluten and casein free diet (GFCF) positively affects children with ASD and recent research from Penn State University  reinforces their observations. There are multiple theories as to why a GFCF diet improves autistic symptoms and it is possible that more than one is correct. Children with ASD who present with gastrointestinal disorders may suffer from intestinal permeability (also called leaky gut) and imbalances in the balance of bacteria that are a normal part of the human intestinal tract. This can result in malabsorption of key nutrients, worsen food sensitivities and inflammation, and increase absorption of toxins through the intestinal wall. All of this increases the stress on children’s developing bodies and brains. Gluten and casein are common allergens which may influence or aggravate these conditions. In addition, the gluten and casein proteins have a molecular structure similar to morphine and are suspected of allowing opiate-like compounds to cross the blood-brain barrier.

Other dietary interventions such as low phenol diets, the Specific Carbohydrate Diet, low oxalate diets, and allergy avoidance diets have been utilized with children on the spectrum. While there is not enough good quality evidence to prove that these diets are helpful, a lack of data does not imply they are not effective, only that more research needs to be done.  As advised by the expert panel, however, when children on the spectrum present with gastrointestinal symptoms, appropriate nutritional intervention is warranted. Finally, epilepsy presents more commonly in children on the spectrum, and in these cases, a low-carbohydrate or MADE (Modified Atkins Diet for Epilepsy) diet may be appropriate.

Probiotics may help address the underlying gut imbalances in ASD since they are essential for normal digestive health. They have been used effectively for many gastrointestinal disorders, and a wide variety of health issues respond to probiotic therapy. They are also known to improve immune function, and alterations in immune balance are additional areas of dysfunction commonly seen in ASD children.

Omega-3 fatty acids are frequently used in the ASD population, and there is evidence that these essential fatty acids (EFAs) can improve symptoms. In one study EFAs showed an advantage over placebo for hyperactivity and stereotypy. While the method of action is not clear, it is theorized that the EFAs role in modulating the immune system and plasticity of brain cells is responsible for the benefits observed.

ASD children are under higher oxidative stress and have reduced levels of antioxidants. Producing the body’s potent antioxidant defenses requires vitamins B6 and B12, folate, and magnesium, among other nutrients. ASD children given folinic acid and B12 supplementation significantly improved their antioxidant status. Lab values of multiple antioxidant nutrients such as zinc, selenium, and Vitamins A and C are lower in ASD children as well. Gut and brain tissue are sensitive to the effects of oxidative stress, so it is essential to support antioxidant production with these critical nutrients.

Up to 80% of children with ASD may have mitochondrial dysfunction( an inefficiency of the energy producing engines of the cell) which could contribute to a number of symptoms including cognitive impairment, language deficits, chronic gastrointestinal problems, and increased oxidative stress. Children with ASD have been shown to have significantly reduced levels of a compound called carnitine, and supplementation significantly improved clinical measurements of autism.

Folic acid is critical during fetal development and needed for numerous biochemical reactions in the body. It requires both niacin and vitamin B12 for proper processing. A larger percentage of children with ASD also have a disorder called Cerebral Folate Deficiency, which reduces the active form of folate in the brain.  In one study, children treated with folinic acid supplementation showed significant improvements in verbal communication, receptive and expressive language, attention, and stereotypy.  Interestingly, human, cow and goat milk have receptors that may interfere with this process as well. This provides further support for the use of a dairy free diet in a subset of children with autism.

Chronic vitamin D deficiency is pervasive in the United States, in both adults and children. Evidence of a relationship between vitamin D and autism includes greater prevalence of autism in areas with greater rainfall and cloud cover, in children born in the spring, and in northern latitudes. Low Vitamin D levels in children with ASD, increased risk of autism in those with darker skin, and increased risk of autism in premature infants have also been observed.

Another antioxidant that has shown promise in Autism is called N-acetylcysteine (NAC). In a pilot trial from Stanford University, a specific formulation of NAC reduced irritability, and repetitive behaviors in children on the spectrum. A formula that comes in individually packaged doses appears to be best, since NAC is very unstable when exposed to light and oxygen. The reason that NAC is effective has not yet been determined, but researchers speculate that it could be a combination of its antioxidant potential as well as NAC’s role in calming overexcited neurotransmitters.

In summary, nutrition therapy for ASD can and should be targeted at the underlying nutritional and biochemical alterations that affect digestion, immune function, oxidative stress, mitochondrial dysfunction and folate metabolism. Foundational interventions to consider include: 1) a “clean” diet, free of the chemicals, pesticides, artificial additives, hormones and antibiotics which may tax poorly functioning detoxification pathways, 2) a diet low in refined and processed foods, low in sugar, and nutrient dense to reduce inflammation and provide antioxidant support, 3) adequate protein for production of glutathione precursors, 4) removal of inflammatory food allergens that may impair gut function, 5) a trial of a gluten and casein free diet, 6) support with high quality probiotics and essential fatty acids to reduce inflammation and optimize intestinal integrity, 7) vitamin D supplementation when clinically indicated, 8) mitochondrial support or folinic acid supplementation when warranted by evidence of mitochondrial dysfunction or CFD, 9) other specialized diets when indicated. It is important to remember that specialized diets are often deficient in one or more key nutrients, and may also result in reduced intake in a child. It is important to work with a qualified nutrition professional who has experience specifically in the area of autism, to insure that diet and nutritional interventions are implemented safely and effectively.



Vicki Kobliner MS RD, CD-N is a Registered Dietitian and owner of Holcare Nutrition (www.holcarenutrition.com). Vicki works with infants, children and adults with digestive disorders, food allergies, ADHD, autism and other chronic illness, and provides fertility and prenatal nutrition counseling. Vicki has extensive experience in using dietary modification, appropriate supplementation and functional lab testing to achieve optimal wellness. She can be reached at 203.834.9949 or vicki@holcarenutrition.com.