Speakers at AutismOne promote all sorts of diets to “cure” autism without any evidence to back it up. They have collections of testimonials , which do not collectively make evidence. While anecdotes may lead to hypotheses for further study, they are not, on their own, evidence. Put somewhat cheekily: the plural of anecdote is not data.

The entire claim that dietary inventions can “cure” autism  completely depends on the idea that autism is curable, which, as we have discussed on this site, contradicts what we know about the genetics and neuroscience of autism.

It is not impossible that dietary changes would improve some specific outcomes (especially given that many dietary interventions lead to an overall increase in fruit and vegetable consumption, which we know is good for overall health and possibly also mental health). However, the claims made by speakers at AutismOne go far beyond any reasonable claim based on the evidence (without disclosing when they meander into speculation). There are also some diets promoted that are actually dangerous and may result in nutritional deficiencies or malnourishment.

Gastrointestinal issues are a fairly common complaint amongst autistic individuals and deserve to be addressed appropriately and with the same level of care as would be addressed in neurotypical children. Research is ongoing for how to address these issues. In particular because of these issues, it is even possible that restrictive diets may actually be detrimental to autistic children.


Here, we provide a few relevant studies collected by the American Academy of Pediatrics about treating GI issues in autism. Note that none of them talk about using these dietary interventions to “cure” or “reverse” autism. The real studies are testing hypotheses about reducing GI systems, ensuring adequate nutrition and possibly improving some specific issues, not about magical claims of “cures” and “restoration”.

Incidence of Gastrointestinal Symptoms in Children With Autism: A Population-Based Study (behind a pay wall so quoting heavily here).

  • “Recently, interest has focused on the potential association between autism and gastrointestinal pathology…Many families, searching for any biomedical intervention that may help their children with autism, have embraced this hypothesis. As a result, restrictive diets and other nutritional or gastrointestinal therapies, such as the gluten-free, casein-free diet; intravenous secretin; prescription of antifungal medications to treat purported fungal overgrowth in the gut; and dietary supplementation with vitamins, minerals, or omega-3 fatty acids have become widely popular interventions for children with autism, despite a lack of evidence regarding their safety or efficacy. Despite this widespread popular acceptance of a link between autism and gastrointestinal disease, epidemiologic studies investigating the relationship between autism and gastrointestinal symptoms are limited. Population-based studies are required to determine whether the incidence of gastrointestinal symptoms in children with autism is truly increased compared with the general population. Thus, the goal of this study was to compare the incidence of gastrointestinal symptoms between children with autism and age- and gender-matched control subjects using a population-based cohort.”
  • Results: “No significant associations were found between autism case status and overall incidence of gastrointestinal symptoms or any other gastrointestinal symptom category.”
  • Conclusions: “Although there may exist subgroups of children with gastrointestinal disorders that contribute to their autistic behaviors, in this population-based study of children with research-identified autism, we found that the overall incidence of gastrointestinal symptoms did not differ between children with autism and control subjects. Children with autism did have an increased incidence of feeding issues/ food selectivity and constipation, problems that may result from behavioral characteristics of children with autism rather than from primary organic gastrointestinal pathology. We did not find that children with autism were more likely to manifest gastrointestinal disorders; specifically, there was no apparent increased risk for inflammatory or malabsorptive disorders. Many children with autism are treated with restrictive diets, vitamin, mineral, and other dietary supplements, as well as various medications aimed at putative gastrointestinal disorders. The findings from our study suggest that such treatments should not be provided indiscriminately to children with autism unless there is explicit evidence indicating the presence of a gastrointestinal disorder in a specific case.”

This meta-analysis from 2014 reaches a different conclusion, Gastrointestinal Symptoms in Autism Spectrum Disorder: A Meta-analysis, highlighting just how difficult these issues are to tease apart and how important well-designed studies are (full text available).

CONCLUSIONS: Results indicate greater prevalence of GI symptoms among children with ASD compared with control children. Identified studies involved high methodological variability and lack of comprehensive data prohibited analysis of GI pathophysiologies (eg, gastroesophageal reflux) typically associated with organic etiologies, limiting conclusions about the underpinnings of the observed association. Future research must address critical questions about the causes and long-term impact of GI symptoms in ASD. Such analyses will require more systematic research and clinical activities, including improved diagnostic screening, standardized assessment, and exploration of potential moderators (eg, dietary restrictions).

Nutrient Intake From Food in Children With Autism (full text available)

Evaluation, Diagnosis, and Treatment of Gastrointestinal Disorders in Individuals With ASDs: A Consensus Report (full text available)



Expert panel sets nutrition guidelines to manage GI symptoms in autism

Nutrition for Children with Autism Spectrum Disorder

Autism Spectrum Disorders (ASD) and Diet


  • See GMO/Glyphosate post for info on why there is no evidence for a link between GMOs or glyphosate and autism
  • There is little risk to a non-GMO diet besides paying more for a non-GMO product that has little to no potential benefit. But for some families, an increased cost of food represents a significant financial burden.
  • There is a possible benefit derived from just increasing fruit and vegetable intake. However, this depends on what the diet was before the intervention and is a separate issue from whether the new diet is derived from genetically engineered food or not.


This is a diet that excludes gluten and diary. These are not easy diets to follow. Elimination of gluten excludes all food containing wheat, oats, barley or rye, all flours, bread, pasta, pastries, and other baked goods made with these grains. The elimination of casein excludes all dairy products: milk, yogurt, cheese, butter, cream, ice cream, etc.

Despite anecdotal evidence for a benefit and some positive findings in unblinded studies, subsequent blinded studies have not supported the idea that the GCFC diet is beneficial for children with ASDs.

Results of a preliminary double-blind clinical trial in 2006 found no statistically significant changes and established that double-blind clinical trials for this dietary intervention are possible.

The gold standard of systematic reviews, the Cochrane Reviews, published this review back in 2008: Gluten- and casein-free diets for autistic spectrum disorder.

A 2010 systematic review of earlier data (paywall) concluded that:

… evidence in support of Opioid-Excess Theory and the resulting treatment of ASD with the GFCF diet is limited and weak. Adverse consequences potentially associated with GFCF diets (e.g., stigmatization, diversion of treatment resources, reduced bone cortical thickness) further the argument against the diet’s therapeutic use. Controversy and conflicting research findings concerning the Opioid-Excess Theory renders other explanations for observed benefits plausible (e.g., biological motivating operations influence behavior). Should a child with ASD experience acute behavioral changes, seemingly associated with changes in diet, practitioners should consider testing the child for allergies and food intolerances, and subsequently eliminate identified allergens and irritants from their environment. Should future research support the therapeutic use of GFCF diets, over and above benefits derived from allergen and irritant avoidance, it would seem reasonable to undertake a controlled trial to determine if a GFCF diet had any additional therapeutic benefit for individual children with ASD.

A 2013 literature review found no available evidence to support a gluten free diet in ASDs. The only double-blind study showed no benefit of this diet.

A systematic review of the GCFC diet from 2014 recommends adoption of a GCFC only in cases where specific allergies to gluten and casein are confirmed. There is not sufficient evidence to warrant putting all children with autism on this diet.

A 2016 study: The Gluten-Free/Casein-Free Diet: A Double-Blind Challenge Trial in Children with Autism. Early results from the same group were discussed here.


The Specific Carbohydrate Diet (SCD) was invented in the early 1900s for celiac disease and expanded into the Gut and Psychology Syndrome (GAPS) diet by Dr. Natasha Campell-McBride in 2004. The idea is that certain foods lead to a “disorganized” gut flora, leading to a range of issues from learning disabilities, psychiatric and psychological disorders, immune system problems and digestive problems. Proponents claim that following this diet removes “the toxic fog from the brain”. This diet combines pseudoscience relating to diet, the microbiome, toxins and heavy metals. This diet is not based on any evidence or research; the reasoning behind it runs counter to basic knowledge of how biology works and proponents make unrealistic and implausible claims about its potential benefits.

This discussion on Science Based Medicine sums the situation up succinctly.

The GAPS diet reflects serious gaps in Dr. Campbell-McBride’s reasoning and in her understanding of science. There is no published evidence to support it. The early introductory stages may not provide adequate nutrition; the full diet is probably healthy but is onerous. It seems very unlikely that it could accomplish all that is claimed. Without testing, there is no way to know whether it benefits or harms patients.

The faulty reasoning behind the diet is discussed here.

A recent and very in-depth discussion of the GAPS diet can be found here at The Angry Chef. A brief excerpt to drive home just how dangerous this diet could be for children:

Just so you have no doubt how serious this is, Zoe Connor, a Dietitian who specializes in working with autistic children who has come across GAPS a number of times, is on the record saying

‘If a child followed GAPS to the letter they could be seriously harmed or even die.’

Imagine the potential for damage here, both physical and psychological. Imagine a frightened and hungry child being deliberately malnourished by its well meaning but terribly informed parents. Imagine a mother and father who are desperate, scared and conflicted. They believe that they are following the advice of a medically trained professional. They are being sold a terrible lie.


A 2017 systematic review found that there is little to no evidence to support the use of nutritional supplements or dietary therapies for improving symptoms of ASD. Tara Haelle has covered this study in Forbes, summarizing the findings in her article:

Assessing the benefits of gluten-free, casein-free diets was difficult because the studies differed so much in how the trial was designed and what outcomes the researchers were looking at. Although parents reported improvements with challenging behaviors and with communication with their children while using a gluten/casein-free diet in a few studies, the data told another story. Or, rather, the data told no story at all.

The trials basically did not yield enough evidence to draw any conclusions about the benefits of eliminating these proteins from children’s diets. Similarly, no changes occurred in autistic children’s behavior or in their gastrointestinal symptoms when they consumed a food containing gluten or casein after being on one of these diets.

Investigations into the use of supplements did not turn up much more.

The only real good news in this systematic review is that harms from these interventions seemed few and far between, though even that cannot be said with certainty.

She concludes:

Further, if parents are forgoing evidence-based therapies that address their child’s specific needs or support they can access locally, then the harm becomes greater. Worse, if they turn to many of the ideas promoted in the dark corners of the internet for autism, they may be trying something that’s not simply harmful but downright cruel, perhaps potentially fatal.

The authors noted that their findings matched up with what previous research reviews have found in assessing the evidence base, but they also acknowledged that many families continue to use supplement or nutritional approaches. Sometimes these diets line up with the parents’ personal views, or they want to feel they are doing something that has fewer perceived side effects.

“These findings continue to highlight the need for shared decision-making among provider and families,” the authors write, “including understanding of family motivations for using specific therapies and discussion of balancing potential benefits with potential risks and resource and time cost to families.”

A 2009 overview of dietary issues in ADHD from the Harvard Mental Health Letter concludes:

A diet or dietary supplement that eases the symptoms of ADHD would be a boon for anyone living with this disruptive disorder. So far, though, the evidence provides only limited support for restrictive diets, avoiding preservatives or artificial food colorings, consuming more omega-3 fats, or taking specific vitamins or minerals.

For now, the consensus on a sensible approach to nutrition for children with ADHD is the same recommended for all children: eat a diet that emphasizes fruits and vegetables, whole grains, healthful unsaturated fats, and good sources of protein; go easy on unhealthy saturated and trans fats, rapidly digested carbohydrates, and fast food; and balance healthy eating with plenty of physical activity.

A healthful diet may reduce symptoms of ADHD by reducing exposure to artificial colors and additives and improving intake of omega-3 fats and micronutrients. But it certainly will improve overall health and nutrition, and set the stage for a lifetime of good health.

In 2011, the FDA Food Advisory Committee met to discuss the issues of food colorings and other additives in ADHD. All documents from this meeting are archived here on the FDA website. The neurotoxicology analysis concluded that artificial food colors are not neurotoxic in children, but that there may be a predisposition for food intolerance or hypersensitivity in certain children (with or without ADHD).

The committee concluded that elimination diets are not recommended to universally treat hyperactivity, about half of the committee favored adding information about these additives to labels, and they recommended further study.