Autism Dietitian


Autism Dietitian Blog

The Gut-Brain Connection in Autism

The gut is often referred to by researchers as the “second brain” because its health and balance of yeast and bacteria can heavily affect cognition, mood, anxiety, and behavior.

What is the Gut-Brain Axis?

Over 2,500 years ago, Hippocrates made the claim that “all disease begins in the gut”. Little did we know, he was right! Recent research shows us that there is a major connection between the gut and the brain, and many scientists and researchers now call the gut the “second brain”. The Gut-Brain Axis (GBA) is the bidirectional link between the central nervous system (CNS) and the enteric nervous system (ENS) of the body [1]. This means that the gut talks to the brain and vice versa, triggering hormones and other bodily signals. For example, a stressful situation could cause gastrointestinal symptoms, or inversely, gastrointestinal symptoms could lead to poor mood, stress, and other neurological symptoms. Two examples would be either anxiety or nerves before a marathon causing gastrointestinal activity (aka the “runs” before the race) or feeling brain fog and hyperactivity after eating a sugary or starchy meal.

In the image below, you can see the relationship between the brain and the gut (involving gut bacteria/microbes and our gut connectome which includes our gut immunity, hormones, and neurons).

Martin CR, Osadchiy V, Kalani A, Mayer EA. The Brain-Gut-Microbiome Axis. Cell Mol Gastroenterol Hepatol. 2018;6(2):133-148.

Martin CR, Osadchiy V, Kalani A, Mayer EA. The Brain-Gut-Microbiome Axis. Cell Mol Gastroenterol Hepatol. 2018;6(2):133-148.


What is the Microbiome?


The term “microbiome” describes the combined environment in your gut that houses trillions and trillions of bacteria, fungi, protozoa, and viruses. Our microbiome environment has been said to be as important as the human genome and as unique as the fingerprint. Everybody’s microbiome is different and has different ratios of bacteria and other organisms. Many of the bacteria or yeast housed in our GI tract are vitally beneficial and help us digest our food, support our immune system, and keep our intestinal cells healthy. It’s important to note that some strains can be extremely detrimental.

Opportunistic bacteria (also known as dysbiotic or overgrown bacteria) make up the harmful bacteria that can be often found in our GI tract. These include (but are not limited to) species like Staphylococcus spp., Streptococcus spp., Pseudomonas spp., Citrobacter spp., and Klebsiella spp. There are also certain strains of bacteria that can be individually detrimental like Enterococcus faecium, Pseudomonas aeroginosa, Staphylococcus aureus, Pevotella copri, and certain strains of Bacillus. It’s important that we can know what kind of bacteria are in the gut so that we can fully understand gut health, which eventually plays into neurological health.

How Does Diet Affect the Microbiome?

Your diet directly feeds the bacteria living in your gut. Beneficial bacteria survive on fibrous foods (think: fruits, vegetables, grains, etc.), while opportunistic bacteria feeds on sugar, simple carbohydrates and starches, meats, and dairy. Many of the children I see with autism and sensory processing disorder have limited themselves to fewer than 10 foods, most of them being carbohydrates, sugars, and dairy. Can you imagine the impact of their diet on their gut, and then the brain? This is why it’s so important to expand the diet when it is limited, as well as address any underlying gut issues.

Alternatively, the way our food is produced can also have an impact on our gut. Non-organic food is sprayed with pesticides to help kill bugs on our food, but this also kills the “bugs” in your gut. It’s important to buy organic and non-GMO produce to promote a healthy gut biome. Antibiotics also have a major impact on your gut bacteria, and it’s not just the bacteria you are orally taking when you’re sick. You must factor in the antibiotics that have been given to the livestock that you are consuming, as those antibiotics will be passed down to you. When purchasing meat, eggs, and fish it’s important that you buy from farms that do not use antibiotics or feed their livestock non-organic grains and soy.

What Are The Symptoms of Dysbiosis and How Can It Be Treated?

Dysbiosis is the imbalance, displacement, and overgrown opportunistic bacteria. Symptoms of dysbiosis include:

  • Bloating & gas

  • Chronic constipation and/or diarrhea

  • Fatigue (commonly from malabsorption of nutrients)

  • Brain fog/difficulty paying attention

  • Impaired digestion of carbohydrates, protein, and/or fats

  • Goofy/silly behavior or laughing at inappropriate times

  • Sugar cravings

  • Food sensitivity

  • …and many others!

Many traditional physicians choose to treat bacteria overgrowth/dysbiosis with antibiotics, but the truth is, this often creates a vicious cycle. The antibiotics kill off both good and bad bacteria, and it’s often the bad bacteria that end up replenishing the gut.

The CDC recommends only using antibiotics when 100% necessary. They say that appropriate times to use antibiotics would be “when treating serious infections, such as pneumonia, and life-threatening conditions including sepsis. Effective antibiotics are also needed for people who are at high risk for developing infections. Some of those at high risk for infections include patients undergoing surgery, patients with end-stage kidney disease, or patients receiving cancer therapy (chemotherapy).”

We can treat dysbiosis by using both diet and nutrition supplements, and most commonly we will do them both at the same time. In my practice, I develop individualized supplement regimens and diets that support the child’s gut makeup and severity of dysbiosis or overgrowth.

Many herbs can be naturally anti-bacterial and anti-fungal. Some of these herbs include:

  • Oregano

  • Thyme

  • Cumin

  • Berberine

  • Black walnut

  • Garlic

  • Grapefruit seed extract

  • Caprylic acid

  • Undecylenic acid

  • You can also use products that have a mix of herbs:

  • These supplements should be used with the guidance of a healthcare professional. I give my personal clients very specific dosages and guidance when taking these supplements.

How Can I Test for Dysbiosis?

The best diagnostic test on the market is the GI-MAP DNA Stool Analysis. I use this diagnostic test with nearly all of my clients to obtain a baseline of gut health and to set the groundwork for our individualized protocol. GI-MAP not only tests for beneficial and overgrown bacteria but also tests for:

  • Fungi/yeast

  • Viruses

  • Parasites + Worms

  • Intestinal health markers

  • Antibiotic resistance genes

  • + Other Pathogens

The stool sample is very non-invasive and relatively easy to collect. My clients will collect the stool sample at home, send it off in the prepaid kit, and we will review results together about 2 weeks after they are received by the lab.


Could Dysbiosis or Yeast Overgrowth Cause Neurological Symptoms?


Certain bacteria and yeasts can release toxins and toxic gasses that can cause damage and inflammation in the GI-tract that can relay to the rest of the body and the brain. Whenever there are longstanding toxins in the GI-tract, it often damages the lining and the integrity of the gut. This can cause the gut to become weak and even can create small perforations, or “holes”. If this happens, these toxins, toxic gasses, and food particles can travel outside of the GI system and can even bypass the blood-brain barrier, causing a direct impact on the brain. This dysfunction in the GI system is called Leaky Gut Syndrome.

The GI-MAP panel tests for a marker called Zonulin, which is secreted whenever the cells in the GI tract separate. This gives us a good idea of how serious the situation is, and how intense we have to be about treatment.

I Suspect My Child Has Dysbiosis or Yeast… What Next?

The best thing you can do for your child is to get them tested and started on the right treatment as soon as possible. It’s important that you are able to see lab results before you start testing for a suspected imbalance or overgrowth. I would love to guide you and your family in this journey to discover the root cause of your child’s GI issues and imbalances. Feel free to schedule a FREE 30-Minute Consult with me to get started! Let’s uncover the best possible version of your child and set them up to feel their very best.