Diet and ASD

Summary: There has been insufficient research to suggest any diet specific to ASD, but plenty to know that everyone requires a balanced diet and sufficient exercise. Some off-the-shelf supplements may help. One excellent guide is the (unfortunately titled) book “Nutrition for Dummies” by Carol Ann Rinzler and you will find similar books at shelf-mark 613.2 in any local library.

1. A Lack of Research

Surprisingly little peer-reviewed research has been conducted on the impact of diet and nutrition on people with ASD. The majority of studies that have been conducted have been too small to detect statistically significant outcomes – we do not know if there is no benefit. Some anecdotal reports and laboratory experiments on animals and or cell cultures are incorrectly used to support a variety of unproven theories about diet in living people with ASD. At its worst, some dietary advice is exploitative and, in some cases, harmful.

2. Balanced Diet and Exercise

Most people eat too much, have an unbalanced diet and do not exercise enough. People with ASD probably have more restricted diets and exercise less than others. There is some evidence that people with ASD have a different metabolism and more gastro-intestinal problems.

There is a wealth of evidence that a healthy, balanced diet aids both physical and mental health. Eating five portions of fresh fruit and vegetables every day, reducing excess calories from fat and carbohydrates, and reducing known irritants (alcohol, caffeine and chocolate) are all beneficial. A healthy, balanced diet is a necessary starting point before using dietary supplements or investigating any personal or ASD-specific food sensitivity.

3. Exclusion Diets and Toxins

Some people with ASD feel better on exclusion diets and some parents report that their children’s behaviour improves on exclusion diets – diet is one of the most frequent interventions and is used by the majority of parents of children with ASD. If you already have a healthy, balanced healthy diet then a qualified gastroenterologist can assess your intolerance to specific foods, such as casein or gluten. “Feeling better” or “behaving better” are subjective judgements that should be treated with care, especially judgements by parents imposing an exclusionary diet on their children. An exclusion diet can be expensive and time-consuming, as well as increasing social isolation – there are not many GFCF-safe birthday cakes, children’s snacks or restaurant menus.

A number of organisations and alternative therapists promote testing for toxins and food intolerances using techniques that are not scientifically proven. There are advertisements for tests for heavy metals, environmental toxins, yeast and bacterial infections, nutritional deficiencies and food intolerance. The same organisations then sell therapeutic diet guides and supplements for people who “test positive” for these factors. Some of these interventions may be beneficial (although the evidence is anecdotal), most do no harm, and some are harmful. However, dietary interventions provide people with ASD with a level of personal control that can improve quality of life, irrespective of any nutritional benefit.

There is no doubt that some individuals have severe food intolerances (e.g. coeliacs) and people with ASD are affected just as much as (and possibly more than) anyone else. Food intolerance can be tested by a gastroenterologist and appropriate exclusions hugely improve the quality of life for people who are food-intolerant.

4. Food Supplements

Many people with ASD and their parents report positive benefits from food supplements, which can be expensive. Scientific evidence of the value of food supplementation is inconclusive (this applies in general, and not specifically to people with ASD) and it is widely recognized that no industry wants to fund research on vitamins and minerals because they will never generate the same profits as patented drugs.

Specific supplements that some people recommend in ASD are magnesium (liquid essence), omega-3 fatty acids, vitamin B (B-complex, B-6, B-12), copolymer Q-10, vitamins A, C & E (the antioxidants) and probiotics (including probiotic yoghurt).


1 Need for Research

Chapman et al (2003) Research into early intervention for children with autism and related disorders: methodological and design issues, Autism 7(2):217-225. “Many different interventions have been suggested as possible treatments for autism, some even claiming to result in ‘recovery’ from the condition. However, adequately controlled studies in this field are few, and randomized controlled trials, other than for pharmacological treatments, are virtually unknown.”

Coury DL et al (2012) Gastrointestinal Conditions in Children With Autism Spectrum Disorder: Developing a Research Agenda. Pediatrics 130:S160-S168. “The underlying nature of GI dysfunction in ASDs and its relationship to etiology and ASD symptoms are poorly understood, and systematic research in this area has been limited.”

Perrin JM et al (2012) Complementary and Alternative Medicine Use in a Large Pediatric Autism Sample. Pediatrics 130:S77-S82. “The review by Huffman et al also documents the need for substantially more study of the efficacy of CAM among children who have neurodevelopmental disabilities. The common CAM treatments (ie, special diets, vitamin and nutrient supplements) have the potential to affect conventional treatments recommended by practitioners operating in the medical home model, and primary care providers should inquire about and be aware of CAM use in their patients and families.”

2 Diet and Nutrition in ASD

Erickson CA et al (2005) Gastrointestinal Factors in Autistic Disorder: A Critical Review. Journal of Autism and Developmental Disorders 35(6):713-727. “a dearth of rigorous study was found to validate GI factors specific to children with autism.”, “Repetitive behaviors and insistence on sameness are core features of autism. These attributes can have a deleterious impact on the patient’s ability to feed effectively and receive adequate nutrition.”

Hyman SL et al (2012) Nutrient Intake From Food in Children With Autism. Pediatrics 130:S145-S153. “Children with ASD, like other children in America, consume less than the recommended amounts of certain nutrients from food. Primary care for all children should include nutritional surveillance and attention to BMI”

Kushak RI et al (2011) Intestinal disaccharidase activity in patients with autism: Effect of age, gender, and intestinal inflammation. Autism 15(3):285–294. “Lactase deficiency not associated with intestinal inflammation or injury is common in autistic children and may contribute to abdominal discomfort, pain and observed aberrant behavior. Most autistic children with lactose intolerance are not identified by clinical history.”

Molloy CA and Manning-Courtney P (2003) Prevalence of chronic gastrointestinal symptoms in children with autism and autistic spectrum disorders, Autism 7(2):165-171. “In a sample of 137 children, age 24–96 months, classified as having autism or ASD by the Autism Diagnostic Observation Schedule–Generic, 24 percent had a history of at least one chronic gastrointestinal symptom. The most common symptom was diarrhea, which occurred in 17 percent.”

Mouridsen et al (2002) Body mass index in male and female children with infantile autism, 6(2):197-205. “The BMI distribution of the male, but not female, children with infantile autism was significantly lower than that of the age-matched reference population.”

Nadon G et al (2011) Mealtime problems in children with Autism Spectrum Disorder and their typically developing siblings: A comparison study. Autism 15(1):98-113. “Children with ASD had significantly more mealtime problems than their sibling living in the same social environment.”

Smith RA et al (2009) Are there more bowel symptoms in children with autism compared to normal children and children with other developmental and neurological disorders? Autism 13(4):343-355. “There is considerable controversy as to whether there is an association between bowel disorders and autism. … This study confirms previously reported findings of an increase in bowel symptoms in children with autism. It would appear, however, that this is not specifically associated with autism as bowel symptoms were reported in similar frequency to a comparison group of children with other developmental and neurological disorders.”

Whiteley P et al (2000) Feeding patterns in autism, Autism 4(2):207-211. “Analysis of parental reports of the specific problems with feeding behaviour revealed problems in three specific areas of feeding: (a) specificity of variety; (b) type and texture sensitivity; (c) dietary load. … Eighty-three percent of parents reported a restricted repertoire of foods serving to make up the child’s core diet. In many cases, any infringement of this set dietary choice was met with food refusal, or in extreme cases behavioural (e.g. tantrums) and physiological reactions (e.g. retching and-or vomiting upon the sight or smell of new foods, or foods not in the child’s set dietary plan). … In conclusion, while recognizing the speculative nature of this, we suggest that some of the types of feeding problems commonly reported as persisting with children with autism may not be exclusively the result of the behavioural characteristics of autism.They may also be the result of certain abnormal biochemical processes involved in the digestion and absorption of specific foods.”

3 Exclusion Diets

Cochrane Database

Claire Millward, Michael Ferriter, Sarah J Calver and Graham G Connell-Jones (January 2009) Gluten- and casein-free diets for autistic spectrum disorder. “There is evidence of widespread use by parents of complementary and alternative therapies (CAM) including exclusion diets for their children with autism. Despite this, there is a lack of evidence to support the use of gluten and-or casein free diet as an effective intervention for persons with autism and also a lack of research on potential harms and disbenefits of such diets.” Cochrane CD003498


Harrington JW et al (2006) Parental beliefs about autism: Implications for the treating physician, Autism 10(5):452-462. “Sixty-nine percent of parents had tried at least one dietary restriction, 60 percent at least one dietary supplement, 63 percent at least one other CAM therapy, and 53 percent at least one medication.”

Elder JH et al (2006) The Gluten-Free, Casein-Free Diet In Autism: Results of A Preliminary Double Blind Clinical Trial, Journal of Autism and Developmental Disorders 36(3). “Group data indicated no statistically significant findings even though several parents reported improvement in their children”

Reichelt KL and Skjeldal O (2006) IgA antibodies in Rett syndrome, Autism 10(2):189-197. “Our data indicate that as a group the girls with Rett syndrome show higher IgA antibody levels in serum against gluten, gliadin and casein proteins compared to controls.”

Sun Z et al (1999) β-casomorphin induces Fos-like immunoreactivity in discrete brain regions relevant to schizophrenia and autism, Autism 3(1):67-83. “Peripheral administration of human β-CM7 at different doses to rats induced moderate to strong Fos-like immunoreactivity in discrete brain regions … shown to be functionally abnormal in autism. … It is concluded that human β-CM7 can cross the blood–brain barrier, activate opioid receptors and affect brain regions similar to those affected by schizophrenia and autism.”

Sun Z and Cade JR (1999) A peptide found in schizophrenia and autism causes behavioral changes in rats, 3(1):85-95. “About 65 seconds after treatment with different doses of β-CM7, rats became restless and ran violently, with teeth chattering and with rapid respiration. Seven minutes later, the rats became inactive with less walking, distancing themselves from the other rat in the same cage, and sitting in, or putting their head against, the corner of the cage. The sound response was reduced and social interaction was absent. One hour later, the rats showed hyperdefensiveness. … The results suggest that β-CM7 may play a role in behavioral disorders such as autism and schizophrenia.”

Vojdani A (2009) Detection of IgE, IgG, IgA and IgM antibodies against raw and processed food antigens, Nutrition and Metabolism 6:22. “We developed an enzyme-linked immunosorbent assay for the measurement of IgE, IgG, IgA and IgM antibodies against raw and processed food antigens. Sera with low or high reactivity to modified food antigens were subjected to myelin basic protein, oxidized low density lipoprotein, and advanced glycation end products (AGE) such as AGE-human serum albumin and AGE-hemoglobin. … Delayed food sensitivity is associated with a multitude of disorders, such as multiple sclerosis, autism and rheumatoid arthritis, and affects an estimated 40% of the population.”

Whiteley et al (1999) A gluten-free diet as an intervention for autism and associated spectrum disorders: preliminary findings, Autism 3(1):45-65. “Results suggested that participants on a gluten-free diet showed an improvement on a number of behavioural measures. However there was no significant decrease in specific urinary compounds excreted when compared with controls and a gluten challenge group.”

Williams KR (2006) The Son-Rise Program® intervention for autism: Prerequisites for evaluation. Autism 10(1):86-102. “The most common type of concurrent intervention was a special diet, with a quarter of all children being given gluten-free and-or casein-free food (n = 12).”

4 Food Supplements

Cochrane Database

Chad Nye and Alejandro Brice (January 2009) Combined vitamin B6-magnesium treatment in autism spectrum disorder. “Studies investigating the effect of vitamin B6 in improving the behaviour of children with autism spectrum disorder have been reported for over three decades. The purpose of this review was to summarize those studies and analyse the effectiveness of vitamin B6 as an intervention. Only three studies met the inclusion criteria of this review and of these only one study reported adequate data for analysis. Results were inconclusive and sample sizes were small. Therefore the use of vitamin B6 for improving the behaviour of individuals with autism cannot currently be supported. Further research using larger, well-designed trials is needed.” Cochrane CD003497

Stephen James, Paul Montgomery and Katrina Williams (December 2011) Omega-3 fatty acids supplementation for autism spectrum disorders (ASD). “It has been suggested that difficulties associated with ASD may be explained in part by lack of omega-3 fatty acids, and that supplementation of these essential fatty acids may lead to improvement of symptoms. The purpose of this review was to assess the evidence for the effectiveness of omega-3 supplementation for core features of ASD and associated symptoms. We found only two small randomised controlled trials that evaluated omega-3 fatty acids for ASD. There is insufficient evidence that omega-3 fatty acids supplementation is an effective treatment for ASD. However, high quality large randomised controlled trials are needed before definite recommendations about this treatment can be made.” Cochrane CD007992

José-Ramón Rueda, Javier Ballesteros, Virginia Guillen, Maria-Isabel Tejada and Ivan Solà (May 2011) Folic acid for fragile X syndrome. “The results of the few published studies did not find significant differences in the effects of folic acid or placebo on psychological or learning capabilities, behaviour or social performance, as measured by standardised tools. There is therefore no evidence to support the recommendation of supplementing dietary intake with folic acid medication for people with fragile X syndrome. However, due to the number and quality of the studies, it is not possible to conclude with any certainty that folic acid does not help.” Cochrane CD008476


Adams et al (2011) Nutritional and metabolic status of children with autism vs. neurotypical children, and the association with autism severity, Nutrition and Metabolism 8:34 “The autism group had many statistically significant differences in their nutritional and metabolic status, including biomarkers indicative of vitamin insufficiency, increased oxidative stress, reduced capacity for energy transport, sulfation and detoxification.”

Main et al (2012) The potential role of the antioxidant and detoxification properties of glutathione in autism spectrum disorders: a systematic review and meta-analysis, Nutrition and Metabolism 9:35. “There is a need for large, well designed studies that link metabolites, co-factors and genes of the g-glutamyl cycle and trans-sulphuration pathway with objective behavioural outcomes to be conducted in children with autism spectrum disorders.”

Page T (2000) Metabolic Approaches to the Treatment of Autism Spectrum Disorders, Journal of Autism and Developmental Disorders 30(5).

Perrin JM and Coury DL (2012) Editors’ Note and Prologue. Pediatrics 130:S57-S58. “When the metabolic consequences of an enzyme defect are well defined (e.g., phenylketonuria, 5′-nucleotidase superactivity), treatment with diet, drugs, or nutritional supplements may bring about a dramatic reduction in autistic symptoms.”

Reynolds A et al (2012) Iron Status in Children With Autism Spectrum Disorder. Pediatrics 130:S154-S159. “Children with autism spectrum disorders (ASDs) often have food selectivity and restricted diets, putting them at risk for nutritional deficiencies. Previous studies have demonstrated a high prevalence of iron deficiency (ID) in children with ASDs … Although the determination of iron status is complex, these data do not support previous reports that children with ASD are at greater risk for ID than the general population; however, 8% percent of the sample did demonstrate low serum ferritin (SF) despite less than 2% of the sample demonstrating iron intake below the estimated average requirement. The prevalence of low SF may be an underestimate …”

Şenel HT (2010) Parents’ Views and Experiences About Complementary and Alternative Medicine Treatments for Their Children with Autistic Spectrum Disorder, Journal of Autism and Developmental Disorder 40:494-503. “At this study, ‘Vitamins and minerals’, with ‘Special Diet’, were highest utilized CAM treatments for the parents of children with ASD in Turkey with finding highly beneficial, which is similar to the results of many studies in the US and other countries (for example; Wong and Smith (2006), and Hanson et al. (2007)). It can be said that the results showed us that parents’ ratings in this study were also optimistic, similar to some of the other studies.”

Wong HHL and Smith RG (2006) Patterns of Complementary and Alternative Medical Therapy Use in Children Diagnosed with Autism Spectrum Disorders, Journal of Autism and Developmental Disorder 36:901–909. “Seventy percent of therapies used in the ASD group were biologically based therapies comprised of special diets or supplements, and parents felt that 75% of the therapies used were beneficial.”

Aitken K (2009) Response to Book Review: Dietary Interventions in Autism Spectrum Disorders: Why They Work When They do, Why They Don’t When They Don’t. J Autism Dev Disord 39:1626–1627. “There is little material easily available to families wishing to explore dietary issues—they typically receive either a ‘hard sell’ or a blanket dismissal. Absence of adequate evidence and evidence of lack of effect are separable issues. As is made clear, many of the diets discussed do not have an adequate evidence-base. Many families adopt dietary approaches in any event, so it is important that potential pitfalls are highlighted rather than dismissing the limited evidence out of hand. Families will often try diets because they access positive reports over the Internet.”

Fitzgerald M (2009) Book Review – Kenneth Aitken: Dietary Interventions in Autism Spectrum Disorders: Why They Work When They do, Why They Don’t When They Don’t. Journal of Autism and Developmental Disorders 39:819–820. “These few random controlled trails cannot be ignored and I take them seriously. In addition some of my clinical experience over the past 35 years in having seen over 1,800 patients with autism spectrum disorders supports it. Nevertheless I still describe this diet to parents as experimental. There is also some scientific evidence for the exclusion of colourings and additives in attention deficit hyperactivity disorder and some benefit for the use of Omega-3 oils in autism spectrum disorder.”

Fitzgerald M et al (1999) Investigation of possible links between autism and coeliac disease. Autism 3(2):193-195. “Because of the very low response rate, no definite conclusions can be drawn. Nevertheless the area warrants more research because some parents reported behavioural improvement in autistic children when a gluten exclusion diet is commenced. Knivsberg et al. (1995) recorded decreased peptide levels and improvements in social communication and communication skills on a gluten-free diet in children with autism.”

Knivsberg, A. M., Reichelt, K. L., Hoien, T., & Nodland, M. (2002). A randomised controlled study of dietary intervention in autistic syndromes. Nutritional Neuroscience, 5(4), 251–261.