Fact or Fiction – Special Diets

Gastrointestinal (GI) issues are frequently reported in autistic people.  As a result, it has been suggested that special diets may help alleviate GI discomfort and improve autism symptoms generally.  Here, we describe the dietary challenges associated with autism, what different specialized diets entail, and what scientific literature says about each diet.

Diet and Nutritional Challenges for Autistic People

  • Nutritional Deficiencies: Nutritional deficiencies are very common in autistic kids.  This can be because autistic children may have preferences for specific foods and reject other foods, leaving them with a limited diet. These unbalanced diets can lead to various kinds of holes in your child’s nutrition.


  • Gastrointestinal (GI) Symptoms: GI issues are common among autistic children.  Common symptoms include: stomach pain, bloating, constipation, diarrhea, nausea, and vomiting.


  • Food Sensitivities: In some cases, the GI issues mentioned above may be the result of food sensitivity, which is common in autistic people.  Some of the more common food sensitivities are casein and gluten.


Gluten-Free Casein-Free Diet (GFCF)

  • What is Casein? Casein is a protein found in milks, eggs, yogurts, cheeses and other dairy products. Some individuals may be sensitive to this protein, causing GI issues. If casein is what is irritating an individual’s stomach, then a casein-free diet may relieve some of the symptoms.


  • What is Gluten? Gluten is a wheat protein found in many breads. Crackers, baked goods, and cereals also contain gluten since many of these foods contain wheat products. Celiac disease, an autoimmune reaction to gluten, is common among those with autism.


  • Why are Gluten-Free Casein-Free Diets Popular? Gluten and casein sensitivities are common among those with autism. Some parents have claimed this diet has helped relieve some of their child’s GI symptoms. Parents have also claimed that the GFCF diet helped improve their child’s ability to concentrate and alleviated repetitive behaviors.


  • What do the Experts Say about the GFCF Diet? While a few parents have claimed improvements to their child’s behavior and GI symptoms, multiple studies have shown that the GFCF diet has no impact on improving GI symptoms nor behavioral issues. Experts do not recommend starting this diet unless your child has a casein or gluten sensitivity. There is a possible risk of nutrient deficiency due to the restrictive nature of this diet. Always speak to your doctor or a nutritionist before changing your child’s diet.



  • This website that explains what gluten and casein are, provides a list of foods that contain gluten or casein, explains the difficulty in maintaining this diet, outlines the nutritional deficits that can come from following this diet, and how to get started with this diet.


Sugar Free Diet:

  • Why do people try Sugar Free Diets? Many children with autism also have hyperactivity disorders (such as ADHD). Some people believe that this excessive energy can be linked to the amount of sugar their children eat. Some parents have claimed that a sugar-free diet has helped their child’s hyperactivity and behavioral issues.


  • What do the Experts Say about Sugar Free Diets? There is very little research to back up claims that a sugar-free diet helps those with autism. In fact, the link between hyperactivity disorders and sugar intake is still being investigated. Some research shows that the consumption of high-sugar foods had no effect on hyperactivity in children. Other research suggests a link between insulin release and autism. Much more research needs to be done before the scientific community can reach a conclusion about the effect of a sugar-free diet on autistic or hyperactive children. Always speak with your physician before changing your child’s diet.


Ketogenic Diet (KD):

  • What is a ketogenic diet? A ketogenic diet consists of a high fat, low carbohydrate diet. By consuming a high amount of fat and a low amount of carbohydrates, the body uses the fats to create a substance called “ketone bodies,” which the brain uses for energy.  You may have heard of this kind of diet before. In recent years, it has become a popular diet for weight loss but has also shown to have potential for helping those who have autism and/or epilepsy.


  • Why do some parents try a ketogenic diet for autistic children?  Autistic people sometimes also have epilepsy (recurrent seizures).  Alongside other preventative measures and/or medications, a ketogenic diet has shown to help prevent seizures in some.  In addition, some studies have shown that a ketogenic diet helped improve their child’s behavioral symptoms.  Because of these two things, some parents try the ketogenic diet in hopes of preventing seizures in their child and improving the behavioral symptoms associated with autism.


  • What do the experts say about a ketogenic diet? Studies have shown a ketogenic diet to be beneficial in helping prevent seizures when used alongside other treatments like anti-seizure medications. Some studies have also reported that a ketogenic diet improved behavioral symptoms in autistic children. Scientists believe this diet helps autistic people by decreasing inflammation, balancing out certain neurotransmitters in the brain, and regulating bacteria in the gut. Overall, the ketogenic diet shows promise as a therapy for autism.


  • Are there any risks to starting a ketogenic diet?  While a ketogenic diet as a therapy for autism does sound promising, some side effects of this diet have been noted.  Always speak with your doctor or nutritionist before changing your child’s diet.
    • Common side effects in children: GI issues such as constipation and vomiting, lack of energy, complaints of hunger
    • Risk of nutritional deficiencies: Many autistic children only eat a limited number of foods. Because of the restrictive nature of this diet, they may be even more limited in the foods that they eat, leading to nutritional deficits.
    • Long-term use of this diet in older individuals may lead to: High cholesterol, hyperuricemia (high amounts of uric acid in the blood), and kidney stones


  • What are probiotics? People in favor of probiotics advocate for ingesting small amounts of live “good” bacteria and/or yeast to promote good health. In particular, probiotics are thought to restore or improve the microbiota (bacteria) of the gut. Though probiotics are generally thought to be safe, it is important to consult with your primary care provider prior to starting probiotic to ensure that they could be of benefit in treating GI symptoms.


  • Why do some autistic people use probiotics?  Compared to their peers, autistic children and adults tend to have more GI symptoms such as abdominal pain, constipation, and diarrhea.  One concern regarding the health of autistic children is the tendency to only eat a few foods (selective eating), sometimes preferring processed foods to fruits, vegetables, and whole grains.  Using probiotics has been shown to help, prevent, and relieve GI symptoms experienced by those with autism.  In addition, recent studies have recognized a “microbiota-gut-brain axis” as a key modulator of neuropsychiatric health, meaning that maintaining a healthy gut microbiota could improve general health, depression, anxiety, and stress.  Probiotics have beneficial effects regardless of an autism diagnosis and could be helpful in relieving some of the GI symptoms present.  Encouraging a balanced, healthy diet is also helpful in preventing GI distress.