By: Ekaterina Dimitrova, dietetic-student volunteer studying at McMaster University, reviewed by the JM Nutrition Team
Before we outline specific nutritional interventions and strategies to help manage ASD in children, we are compelled to define what autism or autism spectrum disorder (ASD) is.
Let’s take a look, shall we?
What is Autism?
ASD stands for Autism Spectrum Disorder. It is a neurodevelopmental disability that affects about 2% of youth aged 1 to 17 in Canada. Most Canadians with autism are diagnosed in early childhood, before the age of 5.
Although the cause of autism remains unknown, many scientists attribute it to a number of factors.
These include: genetic predispositions, epigenetic factors, neurological factors, metabolic factors, psychological factors, mitochondrial dysfunction, environmental factors, cellular stress or combinations of these.
These factors are believed to impact neuronal pathway dysfunction, neurotransmitter imbalances, neurodevelopment and neural connectivity.
Undoubtedly, autism can manifest itself in many different ways amongst individuals.
How does Autism or ASD manifest itself?
For example, while some may have a high conversational aptitude, others may be non-verbal.
Common symptoms involve repetitive behaviours and nonverbal communication. Other symptoms may include delayed language development, distinct reactions to sensory input (e.g. light, colours, textures, smells, etc), difficulty with fine motor skills or intense reactions to minor changes in routines or surroundings.
Signs and symptoms vary greatly. This makes individualized approaches to treatment important for successful clinical outcomes. We cannot underscore this enough.
Dietary Impact of ASD and Feeding Behaviours
Children with ASD experience higher rates of feeding problems and dysfunctional behaviours during mealtime compared to children without autism.
Common behaviours include:
- Refusal to eat
- Food selectivity/Limited food variety
- Reluctance to try new foods
- Ritualistic patterns and behaviours
About 30 to 84% of children with ASD have issues with food intake. Unfortunately, this can lead to poor nutritional and health outcomes, including gastrointestinal disorders and nutritional deficiencies.
Depending on the foods they eat and avoid, children with ASD may be at risk of lacking nutrients. These include iron, calcium, zinc, iodine, selenium, and vitamins A and B12.
Additionally, studies show that children with ASD have altered gut microbiota compared to neurotypical counterparts.
Problems with food intake and eating behaviours can be attributed to cognitive and motor impairments commonly observed in children with autism. These can manifest as intellectual disabilities leading to self-feeding limitations. They can also lead to problems with chewing and swallowing.
Sensory dysfunction is also highly prevalent, affecting about 74% of people with ASD. Hypo- or hyper-sensitivity to stimuli related to the food or feeding (e.g. colour, temperature, texture or presentation of the food) can lead to atypical feeding behaviours and food selectivity.
How to manage food selectivity in autism or ASD
Food selectivity affects 21 to 76% of people with ASD. This is mainly attributed to sensory dysfunction. What’s more, food selectivity can impact weight, nutrient intake, gastrointestinal issues and metabolic issues.
Furthermore, gastrointestinal issues are directly linked to restricted diets (in quality and quantity). Consequently, this impacts nutrient intake and intestinal health.
Behavioural interventions are the most common and effective for improving picky eating in children with autism. These interventions can incorporate a variety of factors and strategies including:
- Structured routines
- Parent education
- Different contexts (e.g. school, home, etc)
- Reinforcement strategies
Studies
Studies have shown that interventions with high parental involvement are significantly more effective compared to those without.
Taste Education, an intervention conducted by scientists at the University of Iceland, performed well in reducing food selectivity among autistic youth in Iceland. Taste Education was a multi-step program that incorporated nutritionists, psychologists, parent education and cooking workshops with children.
The program ran for several months. Kitchen sessions were led by nutritionists and psychologists as children were accompanied by their caregivers. These sessions involved parent-child games, interactive activities, sensory evaluation and food preparation skills.
Parents were instructed to help children only when necessary and provide encouragement. Parents were also encouraged to taste food and describe the taste with positive or neutral language.
Children were encouraged, but not pressured, to taste new foods. They were also encouraged to avoid using words like “yuck” or “disgusting” and instead describe the taste experience (e.g. “ ‘I don’t like this because it’s too soft’ or ‘The taste is too bitter’ ”, Thorsteinsdottir, 2021).
All recipes were designed to be “easy-to-follow” (Thorsteinsdottir, 2021). They also included numbered instructions, clear fonts and images.
In the end, these strategies helped reduce food selectivity with results maintained 6 months after the program.
Overall, evidence indicates that behavioural approaches involving direct parent involvement are the most effective at improving picky eating in children with ASD.
Nutritional Interventions to Improve ASD Symptomology
In addition to strategies regarding improving dietary behaviours and habits, nutritional interventions can also be utilized to help alleviate ASD or autism symptomology.
Gluten-Free Casein-Free Diet (GFCF)
Gluten-free casein-free diet may be an effective nutritional intervention or strategy to manage ASD.
Gluten and casein are types of proteins found in rye, wheat and barley and milk, respectively.
It is hypothesized that these proteins stimulate the production of antibodies that are believed to exacerbate symptoms of ASD.
Another hypothesis is that these proteins are metabolized into short-chain peptides in the intestine, resembling those involved with behavioural problems (gluteomorphins and casomorphins).
Since people with ASD tend to have higher rates of intestinal inflammation, their intestines are more permeable to these short-chain peptides, allowing them to enter the bloodstream.
Due to these hypotheses, some scientists believe that eliminating gluten and casein from the diet can help alleviate some symptoms of autism. In a casein-free diet, dairy products are completely restricted. Products containing lactose are also restricted. Gluten-containing grains are restricted in gluten-free diets.
Related: dietitians for gluten-free diet support
Case studies
For example, a study was conducted where a group of children with ASD were put on a GFCF diet (with supplementation) for 12 months and assessed.
Results revealed significant improvements in nonverbal IQ, ASD symptoms and nutritional status. However, results vary. Some report improvement. Others, on the other hand, observe no results along with potential risk for negative gastrointestinal symptoms.
Another study, conducted on rats, observed that diets high in gluten and casein exacerbated ASD symptoms.
Overall, there is some evidence that supports potential benefits for a GFCF diet. However, more extensive research needs to be conducted in order to confirm this effect. Therefore, the GFCF diet is not currently an evidence-based treatment for core symptoms of autism.
Ketogenic Diet
The ketogenic diet may also be an effective ASD nutritional intervention or strategy.
The ketogenic diet is a high-fat low-carb diet that aims to maintain the body in a state of ketosis. Ketosis happens when the body is deprived of carbohydrates, the body’s main source of energy. Instead, it meets its energy demands by transforming fats into ketone bodies.
In recent years, the keto diet has been used to help treat some neurological disorders. An example of this would be epilepsy.
The ketogenic diet has been shown to improve the gut microbiome by increasing colonies of beneficial bacteria and improving absorption of fatty acids. Although, many side effects of the diet also exist, including fatigue, headaches, vitamin and mineral deficiencies, and gastrointestinal complaints, such as constipation.
Studies
Many small-scale studies have been conducted to determine the association between the keto diet and ASD. Some rat studies observed that the keto diet helped improve mitochondrial function in rats with ASD mutations. Human studies have shown mixed results.
One study conducted in 2018 recruited kids ages 2-17 diagnosed with ASD. The group was put on the keto diet and assessed after 3 months. Out of the 15 participants, 6 showed substantial improvement, 2 showed moderate improvement and 7 showed minimal or no improvement. The ADOS-2 (Autism Diagnostic Observation Schedule, Second Edition) assessment revealed improvements in core autism features. The CARS-2 (Childhood Autism Rating Scale, Second Edition) revealed significant improvements in imitation, body use, fear and nervousness.
Similar studies have also demonstrated improvements in social deficits, repetitive behaviours, memory impairments and inflammatory markers.
Although there is some evidence that shows potential benefits of a keto diet, higher quality research needs to be conducted to determine the validity of the association.
Related: Pros and cons of keto diet
Vitamin D
Vitamin D intake may also be a beneficial nutritional intervention or strategy or ASD.
A meta-analysis comparing 24 studies revealed that children and teens with ASD had significantly lower vitamin D levels than their neurotypical counterparts.
There have also been consistent findings associating low vitamin D with higher risk for ASD.
Additionally, research has demonstrated that reduced vitamin D during neonatal development and early infancy increases risk of developing ASD by 54%.
However, the biological mechanism behind these associations remains unclarified. It’s important to consider that vitamin D and ASD do not always have a cause and effect relationship.
Vitamin D is important for neurodevelopment, neurotransmission and immune functions.
Some studies have observed alleviation of autism symptoms associated with vitamin D supplementation. This nutritional intervention is one of the most promising. However, further research is required with larger sample sizes and longer observation periods in order to make a generalized conclusion.
Conclusion
Other nutritional interventions and strategies for ASD have also been proposed. However, they have limited research to back up claims. At least at the time of writing.
In addition, it’s important to note that these nutritional interventions may not be suitable for everyone.
There can be risks associated with putting children with ASD on a diet. This is especially true on restrictive diets such as the ketogenic and GFCF diets. This is particularly true for children that already face significant struggles with feeding behaviours or food selectivity.
There is no nutritional intervention that can definitively help manage or improve ASD. There may be some scientific evidence showing benefits in certain individuals. That said, however, the research in this field is limited in quantity and quality.
Nevertheless, dietitians who work with ASD can help manage dietary challenges often encountered by children with ASD.
Without a doubt, nutritional interventions and strategies for ASD should be individualized. This is especially true since ASD can present itself vastly differently amongst patients. Nutritional strategies must take into account the needs, accessibility and symptoms of the patient.
Consult a registered dietitian or nutritionist that specializes in ASD. Doing so could help you discover individualized strategies to help your child.
Should you feel you require personalized sessions for guidance around pediatric nutrition support, ASD strategies and nutritional interventions, or other related matters, book a free consultation or contact us for an appointment.
References
1. About Autism Spectrum Disorder. (2026, April 13). Retrieved from U.S. Centers for Disease Control and Prevention website: https://www.cdc.gov/autism/about/index.html
2. Autism: Signs and characteristics. (2025, February 12). Retrieved from Government of Canada website: https://www.canada.ca/en/public-health/services/diseases/autism-spectrum-disorder-asd/signs-characteristics.html
3. Autism spectrum disorder: Highlights from the 2019 Canadian health survey on children and youth. (2022, February). Retrieved from Government of Canada website: https://www.canada.ca/en/public-health/services/publications/diseases-conditions/autism-spectrum-disorder-canadian-health-survey-children-youth-2019.html
4. Esposito, M., Mirizzi, P., Fadda, R., Pirollo, C., Ricciardi, O., Mazza, M., & Valenti, M. (2023). Food selectivity in children with autism: Guidelines for assessment and clinical interventions. International Journal of Environmental Research and Public Health, 20(6), 5092. https://doi.org/10.3390/ijerph20065092
5. Lee, R. W. Y., Corley, M. J., Pang, A., Arakaki, G., Abbott, L., Nishimoto, M., … Wong, M. (2018). A modified ketogenic gluten-free diet with MCT improves behavior in children with autism spectrum disorder. Physiology & Behavior, 188, 205–211. https://doi.org/10.1016/j.physbeh.2018.02.006
6. Ozler, E., & Sanlier, N. (2025). Nutritional approaches in autism spectrum disorder: A scoping review. Current Nutrition Reports, 14(1), 61. https://doi.org/10.1007/s13668-025-00655-y
7. Schopf, C., Assmann, M., Wolke, N., Frenser, M., Marquardt, T., & Fischer, T. (2026). Adverse events and tolerability of ketogenic diets – a systematic literature analysis. BMC Nutrition, 12(1), 44. https://doi.org/10.1186/s40795-026-01277-5
8. Siracusano, M., Arturi, L., Riccioni, A., Medoro, A., Savino, R., Scapagnini, G., … Mazzone, L. (2025). Feeding difficulties, eating disorders and therapeutic approaches in autism spectrum disorder: An overview. Pharmacological Research, 222, 108040. https://doi.org/10.1016/j.phrs.2025.108040
9. Song, L., Luo, X., Jiang, Q., Chen, Z., Zhou, L., Wang, D., & Chen, A. (2020). Vitamin d supplementation is beneficial for children with autism spectrum disorder: A meta-analysis. Clinical Psychopharmacology and Neuroscience, 18(2), 203–213. https://doi.org/10.9758/cpn.2020.18.2.203
10. Thorsteinsdottir, S., Njardvik, U., Bjarnason, R., Haraldsson, H., & Olafsdottir, A. S. (2021). Taste education – A food-based intervention in a school setting, focusing on children with and without neurodevelopmental disorders and their families. A randomized controlled trial. Appetite, 167, 105623. https://doi.org/10.1016/j.appet.2021.105623
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