Serotonin-The Misunderstood Chemical

Scott Braver
5 min readAug 22, 2020
Photo by Nathan Dumlao on Unsplash


Sooooo, this is kind of a tricky, technical topic that often gets misinterpreted or misconstrued in a way that can confuse the general populous and the exquisite relationship between neurotransmitters and gut health.

For the longest time, scientists had no idea that serotonin was so prevalent in our GI tract. In fact, we theorized that was strictly limited to the brain as a neurotransmitter, inversely related to dopamine.

Fairly recently, there have been big strides in the understanding of the intestinal microbiome (normal bacteria) and the relationship to neurology. This new term is called microbial endocrinology.

What that essentially means is that scientists are now able to study the ability of microorganisms and their ability to produce and respond to neurochemicals that originate within the organisms themselves or within their host (AKA- you).

It has been shown that stress (engagement of the sympathetic nervous system- ‘fight or flight’) can act through the nervous system and can effectively influence the microbiota through hormonal changes in the pituitary gland.

Interestingly, this means the gut microbiota and our neurochemicals work in a bidirectional pathway. Without getting too technical with the vocabulary, this means that the host (you) and microbiota can influence each other in response to stress, immunologic pathways, and neurochemically.

Pretty crazy, right?!


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Now that we have a little history and how the bacteria in our gut can work proportionately well with our neurotransmitters (serotonin and dopamine) let’s look more specifically at how serotonin can impact our overall health.

Roughly 95% of serotonin in the body is located in the stomach, whereas only 5% is located in the brain.

95%!! Can you believe that??

I certainly didn’t when I read that statistic from the US National Library of Medicine’s National Institute of Health!

Serotonin can actually affect the peristaltic movement in our intestines and actually plays a role in IBS disorders or people with chronic constipation.

Exactly how does serotonin affect our gut when it is classified as a neurotransmitter? Well, after serotonin is released in the cells lining our gut, it flows to and binds to receptors on nerve endings in the intestinal wall.

Having good intestinal lumen health is directly related to how long serotonin remains in the gut wall once it is released.

Let’s try and recap and understand why serotonin is an important neurotransmitter if it is predominantly found in the gut. Plus, how can it affect our immunologic responses?

To keep things really superficial, serotonin is a hormone that helps stabilize our mood, provides feelings of well being and happiness. In contrast, dopamine helps control motor movements and emotional responses to pleasure, attention, mood, and motivation.

We just learned that there is a bidirectional response to the gut microbiome and serotonin.


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Let me ask, what would happen if our gut microbiome is affected by our dietary choices?

Can you see the cause and effect there? Does a light bulb go off in your head yet?

It should! The food we put in our body has a DIRECT correlation to our gut bacteria and that gut bacteria affects the hormonal interrelationship that then communicates with the rest of our body to execute core functions like gastric motility, pain perception, happiness, and immunologic responses.

We have to look at the body as a WHOLE system and not compartmentalize it like many physicians are trained to.

I clearly illustrated the downregulation of what occurs when we make poor dietary choices and it starts at the cellular level and works its way up to the whole body.

Our gut microbiome is certainly unique to us and it greatly influences our quality of life. If we constantly feed our ‘garden’ calcified water and never put manure down, we are doing a big disservice to our garden.

Think of our gut microbiome as a thriving garden with a potpourri of varying spices, herbs, fruits, and vegetables. We all know that we need to feed, water, and care for our garden in order for it to become fruitful, right?

The same goes for our gut microbiome. We need to feed it foods that allow a healthy environment for it to grow, diversify, and thrive within our body. Once our garden dies, our immune responses are heightened, pain receptors can become irritated, we experience bloating, diarrhea, and malabsorption of nutrients.

From there, our intestine walls become weaker and that nice little protective coating that we have in place breaks down.

Once it breaks, we have cracks in our amour. Good and bad bacteria can then escape our GI tract and travel throughout our body because of our vast and expanding lymphatic and vascular system.

Now we have bad bacteria that are infiltrating our vital organs and producing significant symptoms that we tend to cope with as ‘normal’.

Like I stated in previous articles, it is NOT normal to have fecal material in your brain. However, that is EXACTLY what happens when we have cracks in our armor and allow food particles, GI contents, and bacteria to leave our gut and travel without restriction through our body.


Photo by Thomas Park on Unsplash

The fatigue that we experience from our body's immune system working on overdrive for years trying to fight off these unknown invaders until finally, they simply give up and can’t tolerate trying to get back to homeostasis.

As a result, the chronic disease begins to flourish. Fibromyalgia, arthritis, asthma, Alzheimer's disease, GERD, chronic diarrhea, inability to concentrate, poor eyesight, high blood pressure, heart failure, diabetes.

The list literally goes on and on.

Can we agree that the right food is HIGHLY important in preventing these chronic disease processes that nobody wants?

It is about taking accountability for your health. Understanding your body and asking the right questions.

Our body works harmoniously to keep us functioning properly. Why do we want to create silos and not treat the UNDERLYING condition? Poor nutritional habits lead to malnutrition, malabsorption, inflammation, chronic disease, and eventual early death.

Next time you eat that oreo or pizza because you feel you deserve it from all the stress you have been going through, think about the downstream effects it has on your body and how you are quite literally shortening your life for 5 seconds worth of pleasure.

Be strong. Be brave.