Gut health and the Gut-Brain Connection have become hot topics over the past 5 years, and for a good reason! Researchers have noted that imbalances in the gut microbiome have been associated with neurodegenerative diseases like Parkinson’s and Alzheimer’s disease, Irritable Bowel Syndrome, and a variety of central nervous system disorders, including anxiety, depression, and even autism[1-4].
Autism Spectrum Disorder (ASD) is a developmental disorder typically diagnosed in the first two years of life, though it can be diagnosed at any age. It is characterized by difficulties in social interaction, communication, and repetitive patterns of behavior and interests. Two lesser known health concerns with autism include chronic gastrointestinal (GI) issues and selective eating, which both can largely affect a child’s nutritional status. Research estimates that autistic children are nearly 8 times more likely to have at least one GI symptom, with constipation being the most common. One research study revealed that 65% of children and adults on the spectrum experienced constipation, 48% experienced stomach aches or stomach pain, 23% experienced nausea, and 30% experienced diarrhea.
Interestingly, GI issues can be directly linked to increased problem behaviors such as self-injurious behaviors, restricted stereotyped behaviors, aggressive behaviors, sleep problems and attention issues[6,8]. Addressing the gut can be foundational in addressing underlying nutrition issues for autism.
A majority of autistic children are selective eaters due to sensory processing difficulties and sensory overwhelm. Since eating is one of the most sensory-rich experiences we have as humans, this makes sense! This commonly causes the individual’s diet to be limited to foods that comfort their sensory needs, including foods like chicken nuggets, french fries, chips, crackers, and often other processed “beige and crunchy” foods. The commonality of these foods is that they often contain very little fiber (a nutrient crucial for gut health), and decreased levels of vitamins and minerals. While eating these foods every now and then wouldn’t make a drastic impact on the gut microbiome or nutrition status, eating them consistently and repetitively can cause an imbalance of the gut bacteria (a term called dysbiosis), increase risk of nutrient deficiencies, and increase the likelihood of gastrointestinal issues like constipation, diarrhea, bloating, and abdominal discomfort.
Some autistic children are non-speaking, making it difficult to communicate when they are experiencing discomfort or pain. Their way of communicating that they are experiencing pain may manifest as self-injurious behaviors like headbanging or hitting, or pushing their stomachs up against furniture to ease the pain. These imbalances may affect their moods and increase tantrums. In addition, having an imbalance of gut bacteria can contribute to neurological symptoms like brain fog, anxiety, fatigue, and an uptick in food sensitivities, all commonly seen in autistic children. This phenomenon of the gut affecting the brain (and vice versa) is more commonly known as the “Gut Brain Connection”.
Working with a dietitian who is familiar with autism can help parents expand their child’s diet and build a positive relationship with food, rather than causing traumatic experiences by forcing a child to eat or removing all of their safe foods in an attempt to get them to eat something new. Expanding the diet to whole, high-fiber foods can help promote gut health, improve nutrient levels, and help the child feel better and thrive. There are a limited number of dietitians who specialize in this area, but thankfully the field is growing. If you are a parent of a child on the spectrum and are looking to get started with nutrition for autism, joining a resource like the Autism Nutrition Library can help point you in the right direction and connect to a community of other parents looking to help their kids feel their best and reach their full potential.
 Casella G, Pozzi R, Cigognetti M, Bachetti F, Torti G, Cadei M, Villanacci V, Baldini V, Bassotti G. Mood disorders and non-celiac gluten sensitivity. Minerva Gastroenterol Dietol. 2017 Mar;63(1):32-37. doi: 10.23736/S1121-421X.16.02325-4. Epub 2016 Sep 20. PMID: 27647538.
 Quigley EMM. Microbiota-Brain-Gut Axis and Neurodegenerative Diseases. Curr Neurol Neurosci Rep. 2017 Oct 17;17(12):94. doi: 10.1007/s11910-017-0802-6. PMID: 29039142.
 Mayer EA, Tillisch K, Gupta A. Gut/brain axis and the microbiota. J Clin Invest. 2015 Mar 2;125(3):926-38. doi: 10.1172/JCI76304. Epub 2015 Feb 17. PMID: 25689247; PMCID: PMC4362231.
 Kowalski K, Mulak A. Brain-Gut-Microbiota Axis in Alzheimer's Disease. J Neurogastroenterol Motil. 2019 Jan 31;25(1):48-60. doi: 10.5056/jnm18087. PMID: 30646475; PMCID: PMC6326209.
 Autism Spectrum Disorder. National Institute of Mental Health Website. Accessed 2021 Nov 29. https://www.nimh.nih.gov/health/topics/autism-spectrum-disorders-asd
 Chaidez V, Hansen RL, Hertz-Picciotto I. Gastrointestinal problems in children with autism, developmental delays or typical development. J Autism Dev Disord. 2014;44(5):1117-1127. doi:10.1007/s10803-013-1973-x
 Ferguson BJ, Dovgan K, Takahashi N, Beversdorf DQ. The Relationship Among Gastrointestinal Symptoms, Problem Behaviors, and Internalizing Symptoms in Children and Adolescents With Autism Spectrum Disorder. Front Psychiatry. 2019;10:194. Published 2019 Apr 9. doi:10.3389/fpsyt.2019.00194
 Restrepo B, Angkustsiri K, Taylor SL, et al. Developmental-behavioral profiles in children with autism spectrum disorder and co-occurring gastrointestinal symptoms. Autism Res. https://doi.org/10.1002/aur.2354