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Gut & Brain

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image004The Link Between Autism and the Gut

According to the CDC, children with autism are nearly 3.5 times more likely to suffer from chronic diarrhea or constipation than their peers. Mass General, a leading hospital in Massachusetts, found that nearly fifty percent of those diagnosed with an ASD will also have gastrointestinal issues, such as diarrhea, constipation, abdominal pain and reflux.

Clinical practices will need to consider the potential of gastrointestinal and health problems in the child’s ASD management as the child may be acting out due to any of the following types of pain: gastrointestinal, dental, migraines, earaches. Common behavior treatments may be deemed ineffective in the event one of the above pains is the cause of the behavior.

Gut and Brain Connection

The gut and brain are connected because the gut can speak to the brain using the body’s immune system, nervous system, or various hormones. In fact, some gut microbiomes release neurotransmitters and communicate through the vagus nerve, informing the brain of what is happening in the gut. Overall, the gut microbiome greatly impacts the body’s immune response and can determine our mental and physical well-being.

While this interaction is known, scientists are still determining exactly why those on the autism spectrum suffer from gastrointestinal disorders. The following are several of the common ideas scientists have pursued in hopes to discover the answer to this question, and which will be discussed throughout this chapter: mom’s stress, baby’s gut, and brain development; gut bacteria and propionic acid; solutions for leaky gut syndrome.

Stress, Gut, and Brain Development

When under mental or physical stress, our body will release inflammatory cytokines, a signaling molecule that helps the message flow from cell to cell in order for the immune system to respond to any areas of trauma, inflammation or infection. As such, cytokines will bring a certain part of our immune system into high alert and cause the body to react to stress as if it were an infection, and to treat chronic stress as a chronic infection. It has long been known that stress during a mother’s pregnancy can cause adverse reactions and even lead to some birth defects, including the child exhibiting symptoms of autism. According to the Pennsylvania Medical School, the baby’s gut microbiomes are populated by the vaginal microbiomes of the mother as the baby is passing through the birth canal. Researchers at Arizona State University continued this study and discovered that participants with autism had fewer bacteria types when born, causing a gut which is more susceptible to disease-causing pathogens. If a mother has been exceptionally stressed during pregnancy, the gut microbiomes passed to her offspring will be directly affected, and may cause gastrointestinal disorders and LT consequences in brain development in the future.

Gut Bacteria and Propionic Acid

Certain antibiotic-resistant bacteria, including Clostridia and other species, can flourish when other bacteria in the gut are killed during antibiotic therapy. These bacteria create propionic acid as a waste product. Dr. MacFabe presented a theory at Neuroscience 2013 (which was conducted with pregnant rats) that hints at a connection between increased propionic in the diet and offspring being born with autism-like symptoms.  The study further identifies that the abnormalities caused by over production of antibiotic-resistant bacteria can weaken the function of mitochondria (known as the cell’s powerhouse), which supplies energy to the cells. Richard Frye from the University of Arkansas also notes that autism, particularly severe autism, may be directly connected to mitochondrial defects.

Doctors and scientists have also been researching ideal methods to affect the gut microbiome and the immune system for reducing gastrointestinal disorders for those with autism. A change in diet will have the most immediate effect on gut microbe composition, hopefully achieving a fine balance of immune regulation. Furthermore, some preliminary research suggests that probiotics can improve gut composition as long as you take them.

Autism and Leaky Gut Syndrome

Intestinal permeability, also known as ‘leaky gut’, refers to the fact that some people have larger than normal spaces between cells of the gut wall. Since these spaces exist in the gut wall, bacteria, toxins, and undigested food can pass through the small intestine and find their way into the bloodstream. Any larger substance which enters the body is recognized as a foreign object by the immune system, which may lead to a food allergy or sensitivity. When the larger substances enter the body, the immune system recognizes it as a foreign object, which leads to an immune reaction such as a food allergy or sensitivity. If the foods which caused the reaction before are eaten again, antibodies will trigger chronic inflammatory responses, which lower IgA levels. Adequate levels of IgA protect the intestinal tract from clostridia and yeast, indicating that when these levels decrease, additional microbe proliferation (more foreign objects) may be allowed in to the intestinal tract. So, when digestion is impaired, absorption of nutrients is effected, and the leaky gut syndrome is also known to cause vitamin and mineral deficiencies.

“Leaky gut syndrome” is said to have symptoms including bloating, gas, cramps, food sensitivities, and aches and pains. Harvard University recognized that different intestinal permeability was found in 43% of patients with autism, but none of the control subjects.


image005As Dr. Axe outlines on his website, there are four main causes of Leaky Gut Syndrome: poor diet, chronic stress, toxin overload, and/or bacteria imbalance. Diet is the most common culprit of Leaky Gut Syndrome as a poor diet can lead to further damage of the digestive tract, especially when consuming large amounts of foods that are known to damage the intestinal lining, such as unsprouted grains, conventional dairy, GMO’s, and sugar. Each of these foods is difficult for the intestines to digest, which will damage your intestinal lining causing leaky gut.

Chronic stress is also known to weaken a person’s all aspects of immunity, which reduces the immune system’s ability to fight off antigens, leading to inflammation and leaky gut. Reducing overall stress should be a high priority for those with autism, which means ensuring a proper diet and exercise, and getting enough sleep.

Additionally, toxins from antibiotics and medications may lead to Leaky Gut Syndrome as they build up in a person’s system. Pesticides, tap water, aspirin, and other NSAIDS are also known to worsen and possibly cause leaky gut. Granted, for those with autism, they may receive antibiotics more often as their immune system may not be able to fight off infections as easily. Whenever possible, be sure to use antibiotics when absolutely necessary.

Lastly, dysbiosis refers to the imbalance of bacteria in the gut, which is another cause of Leaky Gut Syndrome. Dysbiosis can be triggered by overuse of antibiotics and inappropriate diet, a healthy diet for both the mother during pregnancy and for the child after born is vital to prevent the presence of dysbiosis.

Common Gut Healing Foods

The following five foods are known to help heal Leaky Gut Syndrome:

  • Bone Broth – contain collagen and amino acids proline and glycine which heal damaged cells
  • Raw Cultured Dairy – consumption of pastured kefir, yogurt, or other raw dairy contains natural probiotics that promote healthy gut function
  • Fermented Vegetables – foods such as sauerkraut, kimchi, and kvass are high in organic acids that help create the proper pH balance within the gut
  • Coconut Products – Coconuts contain fats that are easier to digest than other fats
  • Sprouted Seeds – chia, flaxseeds, and hemp seeds help support beneficial bacteria growth


Several connections have been made between the gut and the brain, all of which point to a change in diet or a need for additional nutrients to help alleviate the common symptoms of a leaky gut. In order to determine what foods should be eliminated from a child with autism’s diet, parents must look for any potential food intolerances or allergies while supporting the child in eating a healthy diet and maintaining a healthy lifestyle.


Emily Deans M.D. (2014). “The Gut-Brain Connection, Mental Illness, and Disease”.

Jody Goddard. (2015). “Autism & GI Problems”.

Autism Speaks. (2013). “Spotlight on the Gut Bacteria-Brain Connection in Autism”.

Fassano, M.D. (2015) “Gastrointestinal Symptoms”.

Dr. Josh Axe. (2015). “4 Steps to Heal Leaky Gut and Autoimmune Disease”.

Dr. Timothy Buie and Dr. Harland Winter. (2010). “Is There a Link between Autism