The Gut-Brain Connection in Autism
In recent years, scientists have uncovered a powerful connection between the gut and the brain—known as the gut-brain axis—that plays a key role in physical, emotional, and mental health. For children with autism, this connection may help explain common challenges like digestive issues, mood swings, and even sensory sensitivities. Understanding how the gut and brain communicate opens up new possibilities for supporting children on the spectrum, starting with simple, effective strategies to nourish the gut and improve overall well-being.
What is the Gut-Brain Axis?
The gut-brain axis is an information superhighway between the nervous system of the gut, which is called the enteric nervous system, and the nervous system of the brain and spinal cord, called the central nervous system. The gut-brain axis is where messages are constantly being sent back and forth communicating important information between the brain and the gut.
The enteric nervous system communicates using the vagus nerve (along with MILLIONS of other nerve cells), gut bacteria, and hormones, and enables messages to be sent back and forth between the gut and brain. The gut-brain axis sends messages about hunger and satiety, emotions, and potential pathogens.
This complex communication system helps to explain why we often experience GI symptoms when we’re anxious or stressed, and on the flip side, experience brain inflammation, anxiety, and trouble focusing when our gut is imbalanced.
The Gut Microbiome
The human gut is home to trillions of microbes, so it's no wonder they can play such a big role in our overall health. Bacteria in our intestines (known as our gut microbiome) have SO many important functions that influence our brain. There are several neurotransmitters that are produced by gut bacteria - including serotonin, dopamine, and GABA.
Gut bacteria also produce short-chain fatty acids that affect brain health, and they can cause dysregulation when they are not present. Our gut also releases hormones and peptides like ghrelin, cholecystokinin, and gastric inhibitory peptide that tell the brain when we are hungry or full, which helps regulate our appetite.
When our gut microbiome isn’t balanced and healthy, we can experience digestive issues, skin problems, autoimmune disease, and struggles with mental health, mood, and brain function. Even more reason to make sure we have good gut health!
How the Gut-Brain Connection Relates to Autism
Emerging research continues to highlight the powerful link between gut health and brain function—an area of growing interest in understanding Autism Spectrum Disorder (ASD). The gut-brain connection offers insight into how digestive issues and imbalances in gut bacteria may contribute to the behavioral and emotional differences seen in many autistic children.
Let’s look at some areas where we’ve seen connections between the Gut-Brain Axis and Autism:
The Gut Microbiome: Children with autism often experience gastrointestinal (GI) symptoms such as bloating, gas, diarrhea, and constipation. [1] Studies have linked disruptions in the gut microbiome, caused by factors like C-section delivery, antibiotic use, and low fiber intake, to an increased risk of ASD. [1] In one study, researchers found higher levels of harmful bacteria in the guts of autistic children, and when those bacteria were reduced through treatment, notable improvements in mood and behavior were observed. [2]
Gut health and mood: Growing evidence shows that gut health plays a key role in mood and overall mental well-being. Inflammation in the gut has been linked to emotional dysregulation and challenges with sensory processing. [3] Because the gut and brain communicate through the gut-brain axis, disruptions in the gut can directly affect brain function. Promising research suggests that improving gut health- through probiotics or anti-inflammatory approaches- can lead to better mood and emotional regulation. [3]
Signs the Gut-Brain Axis May be Imbalanced
Signs of poor gut health show up in ways we might not expect, especially in children with autism. From digestion to mood, sleep, and even skin conditions, the gut-brain connection can impact various areas of health and behavior. Below are some common symptoms that may point to an imbalanced gut and signal the need for extra support.
Digestive symptoms - Many children with autism struggle with GI symptoms like gas, bloating, diarrhea, constipation, and tummy aches, and these are all signs the gut may need some extra support and attention.
Food cravings or aversions - Sometimes children with autism crave certain flavors, textures, or even colors of food. On the flip side, children with autism also may have strong aversions to certain flavors and textures as well. If your child is eating a very limited diet, and meal time feels like a struggle, your child may benefit from support from a dietitian. You can learn more about food aversions in this podcast.
Mood swings, anxiety, irritability - The gut-brain axis has an influence on mood and emotional health, so if your child is especially struggling with mood and emotions, this could be a sign that something is off.
Sleep difficulties - In the same way the gut-brain axis can affect mood, it can also affect sleep. While poor sleep can impact our gut health, an imbalanced gut-brain axis can also negatively impact our sleep.
A study done by UC Davis Health found preschoolers with ASD were almost 3 times as likely to have gastrointestinal symptoms than their non-ASD peers. Of those autistic children with GI symptoms, they experienced more significantly more sleep disturbances and behavioral issues than those without GI issues. [6] Focusing on gut health can greatly improve our ability to fall asleep and stay asleep, since the gut microbiome plays an important role in regulating our sleep-wake cycles. [4]
Trouble focusing or concentrating - If your child is having a hard time staying focused, especially when reading or doing school work, it may be worth checking out their gut health. Since the gut and brain are so closely connected, improving gut health can help ensure proper brain function, which can improve focus and overall cognitive function. [5]
Eczema/skin symptoms - Eczema can affect up to 20% of children, and many develop symptoms before the age of 5. In a study done on infants in Hong Kong, they found that infants with eczema had much higher amounts of Bifidobacterium in their gut compared to infants without eczema, suggesting the gut microbiome plays a role in the development of eczema in children. [7]
Supporting the Gut for Better Brain Health
Supporting gut health starts with the basics: balanced nutrition, hydration, and, when needed, targeted supplementation. This section explores practical steps you can take to build a gut-friendly diet and when it might be helpful to consider supplements.
Balanced, whole-food nutrition:
Include foods high in fiber that help feed healthy bacteria in the gut. Try adding in foods like fruits and vegetables, nuts and seeds, whole grains, and beans and lentils to boost your child’s fiber intake.
Try to offer a variety of high fiber foods each day. Different foods contain different types of fiber, so the more varied your child’s diet, the better for the microbiome.
Studies have linked ultraprocessed foods to changes in the gut microbiome, leaky gut, and intestinal inflammation, so trying to minimize processed foods is an important step in improving gut health. [8]
Probiotic and prebiotic-rich foods:
Probiotic-rich foods promote healthy bacterial growth in the gut, so including foods like yogurt, kefir, and fermented veggies like sauerkraut and kimchi can boost gut health.
Prebiotic-rich foods feed healthy bacteria in the gut, so adding in foods packed with a variety of prebiotics like apples, asparagus, bananas, oats, garlic, and whole wheat help keep those gut microbes happy and thriving.
Hydration:
Water is essential for healthy digestion, aiding the gut in breaking down food and absorbing nutrients. It also supports the gut microbiome by keeping the lining of the gut healthy.
Water also impacts our brain function. Since the brain is about 75% water, it requires proper hydration to function well. Dehydration can lead to impaired cognitive function and changes in mood and behavior, so staying hydrated is a must for brain health!
Supplements for supporting gut health and treating dysbiosis
It can be common for kids with autism to eat a limited diet and struggle to add in new foods, so if you feel like your child isn’t able to get enough fiber or nutrients with their current diet, it may be wise to incorporate supplements. Here are a few you could try:
Probiotics - Look for a probiotic supplement with a variety of bacteria. You can find my favorite options here.
Prebiotics - Prebiotic fibers are a great addition to probiotics, and many probiotic supplements have prebiotics added. Just check out the ingredient label to see if your probiotic has added prebiotics!
There are other gut health supplements, like digestive enzymes and herbs to treat dysbiosis, but it is best to work with a Registered Dietitian who can order a stool test (or other testing) to help determine which supplements would be most beneficial.
Realistic Tips for Parents
If all this is feeling a little overwhelming, and you’re not sure where to begin, here are a few tips to help you get started:
Start with one meal or snack a day to include gut-friendly foods. Maybe you could try oats or yogurt for breakfast, or work in an extra fruit or veggie at lunch. Once you’ve mastered that, you can add in another small change.
Watch for patterns between food, digestion, and behavior. Consider a simple food-mood-poop journal where you track your child’s food, behavior/mood, and bowel movements. Sometimes that can give you insight into what to focus on first. It can also be a great tool to make connections between what they are eating and how it is affecting their brain and gut.
Think about what change would be easiest to make, and start there. Maybe overhauling your child’s diet sounds daunting, but you could add in some probiotic foods, or work on increasing their water intake. Any step in the right direction is a win, no matter how small!
When to Seek Help
You may be wondering when to reach out to a Registered Dietitian or healthcare provider if your child is experiencing GI issues. Trust your gut (no pun intended!) - if your child has symptoms that are chronic, or affecting their quality of life, it's best to work with a professional to come up with a plan that can help your child feel their best.
A dietitian or GI specialist can help by doing specific testing - like stool testing, food sensitivity testing, and other labwork - that can help narrow down where the problem is and allow you to focus on the strategies that will get your child relief the fastest.
If you're feeling unsure about where to start, remember that small steps make a big difference, and partnering with a qualified professional can provide the guidance you need to support your child’s gut and brain health with confidence. One place you can find support is through the Nourishing Autism Collective, a community of autism moms who are guided by a Registered Dietitian with information, tips, and insight to help you on your autism journey.
👋 Need help with your child’s nutrition and Selective eating?
Join the Nourishing Autism Collective for expert guidance, a supportive community, and sensory-friendly strategies that actually work.
MEET BRITTYN, THE AUTISM DIETITIAN
Brittyn Coleman is a Registered Dietitian and autism specialist. She helps parents of kids on the spectrum expand their number of accepted foods and maximize their nutrition to help them feel their best & thrive!
You can find her on Instagram at @autismdietitian or on Facebook!
References:
[1] Taniya MA, Chung HJ, Al Mamun A, Alam S, Aziz MA, Emon NU, Islam MM, Hong SS, Podder BR, Ara Mimi A, Aktar Suchi S, Xiao J. Role of Gut Microbiome in Autism Spectrum Disorder and Its Therapeutic Regulation. Front Cell Infect Microbiol. 2022 Jul 22;12:915701. doi: 10.3389/fcimb.2022.915701. PMID: 35937689; PMCID: PMC9355470.
[2] Kang D., Adams J., Gregory A., Borody T., Chittick L., Fasano A., et al. (2017). Microbiota Transfer Therapy Alters Gut Ecosystem and Improves Gastrointestinal and Autism Symptoms: An Open-Label Study. Microbiome 5 (1), e00413–20. doi: 10.1186/s40168-016-0225-7
[3] Doney E, Cadoret A, Dion-Albert L, Lebel M, Menard C. Inflammation-driven brain and gut barrier dysfunction in stress and mood disorders. Eur J Neurosci. 2022 May;55(9-10):2851-2894. doi: 10.1111/ejn.15239. Epub 2021 May 17. PMID: 33876886; PMCID: PMC9290537.
[4] Paromita Sen, Alicia Molinero-Perez, Kenneth J. O’Riordan, Cian P. McCafferty, Ken D. O’Halloran, John F. Cryan. Microbiota and sleep: awakening the gut feeling, Trends in Molecular Medicine, Volume 27, Issue 10, 2021, Pages 935-945, ISSN 1471-4914, https://doi.org/10.1016/j.molmed.2021.07.004.
[5] Fekete M, Lehoczki A, Major D, Fazekas-Pongor V, Csípő T, Tarantini S, Csizmadia Z, Varga JT. Exploring the Influence of Gut-Brain Axis Modulation on Cognitive Health: A Comprehensive Review of Prebiotics, Probiotics, and Symbiotics. Nutrients. 2024 Mar 10;16(6):789. doi: 10.3390/nu16060789. PMID: 38542700; PMCID: PMC10975805.
[6] Restrepo, B., Angkustsiri, K., Taylor, S.L., Rogers, S.J., Cabral, J., Heath, B., Hechtman, A., Solomon, M., Ashwood, P., Amaral, D.G. and Nordahl, C.W. (2020), Developmental–behavioral profiles in children with autism spectrum disorder and co-occurring gastrointestinal symptoms. Autism Research, 13: 1778-1789. https://doi.org/10.1002/aur.2354
[7] Chan CWH, Yuet Wa Chan J, Leung TF, Choi KC, Tsui SKW, Wong CL, Chow KM. Altered Gut Microbiome and Environmental Factors Associated with Development of Eczema in Hong Kong Infants: A 4-Month Pilot Study. Int J Environ Res Public Health. 2020 Oct 20;17(20):7634. doi: 10.3390/ijerph17207634. PMID: 33092052; PMCID: PMC7589899.
[8] Whelan K, Bancil AS, Lindsay JO, Chassaing B. Ultra-processed foods and food additives in gut health and disease. Nat Rev Gastroenterol Hepatol. 2024 Jun;21(6):406-427. doi: 10.1038/s41575-024-00893-5. Epub 2024 Feb 22. PMID: 38388570.
Updated August 2025
