February 14, 2024

Could the Gut Microbiome be the way out of a “Brain” problem?

The gut microbiota, or the bacteria in the gut, have many effects on the body, including the brain. There is a bidirectional connection between the gut and brain called the gut-brain-axis. Could modulation of the gut microbiota be the way out of some our most common psychiatric disorders?

The gut microbiome, or the bacteria in the gut, have many effects on the body, including the brain. There is a bidirectional connection between the gut and brain called the gut brain axis. Could modulation of the gut microbiota be the way out of some our most common psychiatric disorders?

Psychiatric disorders like autism and attention deficit disorders (ADD) are on the rise. A study done in the Journal of Pediatrics reported that there has been a 500% increase in the prevalence of autism from the year 2000 to the year 2016 making it one of the most common neuro-developmental disorders among US children4. Why such a dramatic increase?

Some of the increase may be due to increased knowledge and acknowledgment of the existence of the condition, but curious minds must ask the burning question … what is causing the disorder in the first place?

Reducing inflammation in the gut and re-balancing the bacterial microbiota has been shown to be an effective treatment for many common psychiatric disorders we see today such as: anxiety, depression, schizophrenia, autism, and ADD.

How are the gut and the brain connected?

Medicine has traditionally taught us to see a cardiologist for a heart problem, a nephrologist for a kidney problem, a pulmonologist for a lung problem, a neurologist for brain problem, and gastroenterologist for common GI complaints….so on and so forth. But isn’t the body really one system working together? Let’s look at how it all is connected…

There is a bidirectional connection between the gut and brain called the gut-brain-axis, and these connections are formed through immunological, neuronal, and neuroendocrine pathways5.

Said more simply….the gut is the master regulator of everything that happens in the body through immune modulation, neurotransmitter production, nutrient digestion and absorption, cell to cell signaling, vitamin synthesis, metabolism, biotransformation, and detoxification plus more!

Psychiatric disorders are commonly treated with medications to alter the amount of neurotransmitters available to the body and the brain. But wait! Those neurotransmitters are synthesized right inside our GI tract…does that mean an imbalance in the GI tract is altering production, absorption and distribution of these neurotransmitters leading to symptoms and disease onset???

The abnormal composition of human microbiota may lead to several illnesses like immune system issues, infections, and neuropsychiatric disorders8.

What causes disruptions to the gut microbiota?

Our standard American diet, environment and lifestyle are the top things that have changed over the years. As a population we like instant gratification with everything – food, entertainment, materials, health etc. And we can get whatever we want when we want it. Think about door dash, amazon next day deliveries, and youtube access.

This has brought about a lack of nutrients in our foods as we tend to eat out and get take out more, our exposures to brain altering EMF’s have dramatically increased with our homes being literally “wired,” and our fast paced lifestyles and the need to have everything now has also put some strain on our adrenal function and connections with things like nature, keeping us in a constant state of demand and fight or flight.

All of these things have the power to alter the homeostasis in the body opening us up to more infections and toxins.

The top concerns in my practice are: Toxins, infections and the gut.

What about the vagus nerve?

We can’t talk about the gut-brain axis without talking about the vagus nerve. The vagus nerve is one of the most important and direct pathways connecting the brain to the gut. The vagus nerve represents the main component of the parasympathetic nervous system, which oversees a vast array of crucial bodily functions, including control of mood, immune response, digestion, and heart rate.

It establishes one of the main connections between the brain and the gastrointestinal tract and sends information about the state of the inner organs to the brain. Animal studies have provided evidence that microbiota communication with the brain involves the vagus nerve and this interaction can lead to mediating effects on the brain and subsequently, behavior1.

An inflamed gut = distress/distorted signally to the brain.

Gut dysbiosis and neurotransmitter production:

Serotonin, dopamine, GABA, glutamate and even melatonin are produced in our GI tract. Proper digestion and absorption of protein is crucial to adequate neurotransmitter production because our neurotransmitters are derived from our amino acids. Our primary source of proteins and the amino acids they contain is through animal meats.

For instance, serotonin is derived from tryptophan an amino acid commonly found in Turkey and blamed for the sleepiness after Thanksgiving dinner. Serotonin plays a crucial role in regulating mood, body temperature, pain perception, food intake and appetite, circadian rhythm, sexuality, memory, and stress response.

Since 90% of serotonin synthesis occurs peripherally in the distal GI tract, it is of no surprise that forthcoming research is linking tryptophan metabolism, and serotonin host levels to the gut microbiota6. A reduction is serotonin is implicated in many psychiatric disorders like anxiety and depression.

Dopamine is derived from the amino acid tyrosine. Dopamine is essential for excitement, mobility, mood, and the execution of activities that involve fast decisions and learning through reward5. The gut microbiota has been shown to either protect dopamine synthesis or contribute to its depletion through inflammatory endotoxin release5.

Dopamine depletion is implicated in the development of parkinson’s disease and clinically is elevated in PANS/PANDAS kids creating that excitatory state. Read more about PANS/PANDAS here.

GABA is an inhibitory neurotransmitter and helps us calm down in times of stress and regulates our stress response as well as reducing anxiety and menopausal syndrome symptoms, boosting immunity, treating depression and insomnia, regulating blood pressure, fighting obesity, improving the visual cortex performance5. GABA is derived from glutamine, ornithine, arginine, and putrescine, and numerous human gut bacteria have been found to contain homologous biosynthesis enzymes7.

In an inflamed body, there is reduced conversion of glutamine to GABA and more conversion to glutamate, which is an excitatory neurotransmitter. An imbalanced gut microbiota that has more pro-inflammatory bacteria present, pathogens, and/or toxins leads to increased glutamate production. Animal studies indicate that the gut microbiota can alter the ratios of hippocampal GABA/glutamate levels, which are critical for synaptic plasticity, learning, and memory mechanisms2.

Gut microbiota and psychiatric disorders:

I hope you are getting the picture now that the microbiota composition has A LOT to do with brain function AND balancing the microbiota is an effective way to treat varying psychiatric conditions. The gut microbes are involved in the development of psychiatric conditions through varying mechanisms:

  • *causing or exacerbating neuroinflammation due to gut dysbiosis
  • *microbial translocation to the systemic circulation
  • *enhanced release of cytokines
  • *dybiosis/inflammation leading to reduced vagal nerve input leading to a lack of “rest and digest”
  • *increase stress sensitivity through constant adrenal activation
  • *immune activation / confusion
  • *super antigen formation
  • *molecular mimickry
  • *immune complex formation
  • *bystander activation

Pro-inflammatory bacteria have been found to block the pathways in the gut that lead to neurotransmitter production and/or promote certain neurotransmitters that are excitatory like glutamate, as discussed earlier. All processes that activate an immune response lead to increased systemic inflammation and disruption of other “biomes” (skin, sinus, genitourinary), break down barriers (blood brain barrier, gut mucosal lining, skin) and chronically activates the adrenals putting the individual in constant “fight or flight.” If the inflammation is not reduced this leads to breakdown of our tissues and organ dysfunction.

How to improve your gut health

Eat a diverse diet full of color and phytonutrient, healthy fats, and adequate protein. Cut out the junk – processed, packaged, and refined foods. Incorporate foods containing live probiotics that support the microbiome like yogurt, kimchi, and sauerkraut. Keep out known food triggers. However, diet really needs to be individualized….there is no one-size fits all diet plan. Read more about Food For Health here.

If you struggle with symptoms or a chronic condition that you can’t seem to figure out, go to your doctor. If your doctor does not talk to you about your diet and lifestyle, find a doctor that will. 99% of chronic disease and symptoms have a diet and lifestyle component and an individualized lifestyle plan can really change your health trajectory.

If you or someone you know is struggling with a chronic disease or symptoms schedule a FREE CONSULT to learn more about how we can help 🙂


  1. Breit S, Kupferberg A, Rogler G, Hasler G. Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders. Front Psychiatry. 2018 Mar 13;9:44. doi: 10.3389/fpsyt.2018.00044. PMID: 29593576; PMCID: PMC5859128.

2. Chang CH, Lin CH, Lane HY. D-glutamate and gut microbiota in Alzheimer’s disease. Int J Mol Sci. 2020;21:1–17.

3. Gao K, Mu CL, Farzi A, et al. Tryptophan metabolism: a link between the gut microbiota and brain. Adv Nutr. 2020;11:709–23.

4. J Shenouda, E Barrett, A Davidow, K Sidwell, C Lescott, W Halperin, V. Silenzio, W Zahorodny (2023). Prevalence and Disparities in the Detection of Autism Without Intellectual Disability. Pediatrics 151 (2): e2022056594. https://doi.org/10.1542/peds.2022-056594

5. Mhanna, Amjad MDa,b; Martini, Nafiza MDb,c,*; Hmaydoosh, Ghefar MDa,b; Hamwi, George MDa,b; Jarjanazi, Mulham MDd; Zaifah, Ghaith MDa,b; Kazzazo, Reem MDa,b; Haji Mohamad, Aya MDe,b; Alshehabi, Zuheir PhDf. The correlation between gut microbiota and both neurotransmitters and mental disorders: A narrative review. Medicine 103(5):p e37114, February 02, 2024. | DOI: 10.1097/MD.0000000000037114Stopińska K, Radziwoń-Zaleska M, Domitrz I. The microbiota-gut-brain axis as a key to neuropsychiatric disorders: a mini review. J Clin Med. 2021;10:4640.

6. Roth W, Zadeh K, Vekariya R, et al. Tryptophan metabolism and gut-brain homeostasis. Int J Mol Sci. 2021;22:2973–23.

7. Quillin SJ, Tran P, Prindle A. Potential roles for gamma-aminobutyric acid signaling in bacterial communities. Bioelectricity. 2021;3:120–5.

8. Stopińska K, Radziwoń-Zaleska M, Domitrz I. The microbiota-gut-brain axis as a key to neuropsychiatric disorders: a mini review. J Clin Med. 2021;10:4640.

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