Autism spectrum disorder, or ASD, is a neurodevelopmental disorder that leads to challenges with social interactions and communication, as well as repetitive behaviors. While these are the three core symptoms that lead to the diagnosis of ASD in children, there is also a very strong association between autism and gut symptoms (especially diarrhea, constipation, and acid reflux, or heartburn).
More and better research studies are still needed to tease out the impact of diet on autism, and what gut symptoms are related to the disease itself versus the dietary patterns and preferences of people with ASD. However, there has already been some fascinating research on ASD and the gut microbiota, as well as the potential impact of dietary changes on neurological symptoms.
Autism and the Microbiome
Altered levels of gut bacteria have been strongly associated with ASD. The average healthy child’s microbiome becomes fairly diverse as they eat an increasing variety of solid foods. However, kids with autism tend to have a much less diverse diet, which seems to lead to a sub-optimal gut microbiome.
Though actual gut microbiome composition varies widely, some bacterial families, like Clostridium (known for C. difficile, a common gut infection, but actually a common and generally harmless bacterial family in the gut), Firmicutes, and Proteobacteria tend to be increased in kids with ASD. The types of bacteria of which these kids have an abundance seem to produce too much of a type of short-chain fatty acid called propionic acid, and they have less of the beneficial bacteria that produce butyrate, a short-chain fatty acid with lots of positive effects on mental health and inflammation.
There are a few case reports of treatments with antibiotics have sometimes helped to reduce anxiety and improve some behavioral measures in kids with autism, which is another fascinating sign that the gut microbiome is involved in their neurological symptoms. However, treatment with antibiotics is (and should only be) short-term – and even short-term use can have negative consequences – so this seems unlikely to become a universal solution.
But probiotics and prebiotics – essentially live bacteria and their food – have a strong potential as a much safer treatment with far fewer side effects or risks.
Prebiotics and Probiotics
For example, a study combining an autism exclusion diet with the prebiotic supplement GOS, a type of prebiotic fiber found in dairy products, beans, and root vegetables, found significant improvements in abdominal pain and bowel habits with the exclusion diet, and additional improvements in anti-social behavior with 6 weeks of supplementation with GOS.
Other studies have looked at a variety of probiotics, including single, highly specialized strains such as L. Plantarum WCSF1, or broad-spectrum probiotic supplements containing multiple different strains (mostly in the Bifidobacterium and Lactobacillus families).
While a person with ASD may see benefits from a standard probiotic, strains and combinations of strains specifically studied for the particular condition you’re looking to treat are much more likely to be effective. Some significant improvements in both gut health and behavioral symptoms were seen with the probiotic blend delPRO in one study (though the study did not have a control group with which to compare the experimental group’s results) and with a blend of L. acidophilus, L. rhamnosus, and B. longum in a different study.
Restrictive and Elimination Diets
Lots of different restrictive diets have been proposed for people with autism, and in some cases they may be very helpful. Artificial colors have been linked to behavior disturbances in kids, and there are also concerns about contamination with toxins and heavy metals (though the FDA does require that all artificial colors be tested for lead, mercury, and arsenic).
Gluten-free and casein-free diets are commonly tried. While there are theories about how and why they work, there isn’t enough evidence to say whether they’re generally useful for people with ASD. Proponents feel that the studies that have been done on the GF-CF diet are too short-term to show much impact.
Some people with ASD may have other issues with gluten- and casein-containing foods, such as lactose intolerance, Celiac disease, or non-Celiac wheat sensitivity contributing to their GI symptoms. Others may have IBS, and may see improvements from a low-FODMAP diet (always followed by a re-introduction phase).
However, the more complex the diet, and the more difficult it is for the whole family to follow, the less likely it is to be feasible. Plus, for those with texture issues or those who have more difficulty eating enough variety as it is, it can be difficult to plan a diet that will give enough nutrition to meet their needs. It’s always a good idea to seek the guidance of your pediatrician, neurologist, or dietitian to discuss the pros and cons of restrictive and elimination-style diets, and how to plan them in a way that makes them nutritionally adequate and feasible for the whole family.
Adding to the Diet Instead of Taking Away?
For people with ASD, the diet is often already quite restricted based on personal preferences and aversions. Difficulties with food based on texture, color, and taste are common. Kids may also recognize that certain foods cause tummy pain, and refuse to eat these foods, even if they can’t verbalize this.
It’s important not to make mealtime a fight. Try to stay calm and don’t allow a power struggle to arise over certain foods. We all deserve the right to choose what foods to eat and what foods not to eat, and a person with autism is no exception. However, it may be helpful to try new foods in combination (such as finely chopped mushrooms sautéed and added to spaghetti sauce) or in different forms to make the texture easier to tolerate (such as peeled and crushed tomatoes in a salsa).
As much as possible, involve your child in the food preparation, and try to make it fun. Get your hands dirty together and allow your kids to acclimate to new foods outside of mealtimes to help decrease anxiety during mealtimes.
Very often, it’s more about what we add to the diet than what we take away. Eating more fruits, vegetables, beans and legumes, and whole grains can increase intake of those healthy, gut-nourishing prebiotic fibers that can then feed the gut microbiome, promote more butyrate production, and improve bowel health and GI symptoms.
Eating fermented foods when possible, such as yogurt with live and active cultures, can introduce probiotic “travelers” which can have a positive impact on the gut microbiome, as well.
Eating a greater variety of foods makes it more likely that the diet will have enough protein, vitamins, minerals, essential fats, and polyphenols to promote a healthy brain, gut, skin, immune system, etc.
And besides all that, focusing on food as the hero rather than the enemy can help to foster a healthier relationship with food, less fear of food, and possibly even less reactivity to it. We are all heavily influenced by our expectations, and people with autism are no exception to this, either.
The subject of neurological and developmental disorders and diet is a hotly debated topic, and one that is quite difficult to study. It’s also essential that it be individualized to the needs of the person with autism and their community or family.
If you’re interested in developing a supportive relationship with a dietitian who can assist with making some of these difficult decisions in a non-judgmental environment, and with helping make some of these recommendations more feasible for your family, please reach out to me or schedule an appointment.
I provide virtual nutrition care services to caregivers and parents living with people with autism, as well as directly to adults with ASD, throughout Colorado, California, Michigan, Arizona, Alaska, and Virginia.
Erica Golden, RDN, LD, IFNCP
Mental Health, Eating Disorders, and Gut Health Functional Dietitian Nutritionist
Erica Golden, RDN