How Does the Gut-Brain Connection Work?

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As often as we talk about “gut instincts” and “gut feelings,” we shouldn’t be surprised to learn there is a substantial connection between our gut and cognitive and emotional health. 

This connection is called the gut-brain axis. It is a complex system that oversees communication between the gut and the brain to benefit your overall health.

Your gut affects your brain via hormone and neurotransmitter production, impacting mood and behavior. Let’s walk through the brain-gut connection.

The Bridge Between Your Central and Enteric Nervous Systems

Chances are you already know about your first brain. Comprised of around 100 billion neurons and even more glial cells, this is the head of your central nervous system (CNS). The spinal cord is the other half of your CNS.

Your second brain is in the enteric nervous system (ENS). This system is known as the “brain in the gut” due to its 200-600 million neurons. (For reference, the number of nerve cells in the ENS equals the number of nerve cells in the spinal cord.)

The network of neurons in the ENS extends from the esophagus to the rectum and controls the gastrointestinal tract or GI tract. It can do this independently of the CNS, sensing stimuli and responding accordingly, all on its own.

When the ENS and CNS need to communicate, they do so mainly through the vagus nerve. This single nerve starts in the brain stem, extends through the neck and thorax, and ends in the abdomen, making it the body’s longest cranial nerve.

Although the ENS can operate independently of the CNS and vice versa, these two systems typically communicate bi-directionally along the vagus nerve. That means sensory information can be sent from the brain to the gut, and also from the gut back to the brain.

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The Role of Your Microbiome

Your gut is full of trillions of live bacteria and other living organisms, collectively known as the gut microbiome. One important role these gut microbiota play is helping produce neurotransmitters that influence mood and cognitive function. Neurotransmitters are chemical messengers that the nervous system uses to communicate between neurons. 

For example, a significant portion of the body’s serotonin, a key neurotransmitter involved in regulating mood, appetite, and sleep, is produced in the gut. 

Other neurotransmitters produced in the gut include gamma-aminobutyric acid (GABA), dopamine, and norepinephrine, all of which play roles in mood and cognitive functions.

Your gut microbes also produce microbial metabolites and other byproducts like short-chain fatty acids (SCFAs) that play a role in the function of your metabolism and immune system.

Here are some other ways healthy gut microbes help us:

Effects of an Imbalanced Gut Microbiome

The gut microbiome is a diverse ecosystem of microorganisms that thrives in a delicate balance. When that ecosystem becomes imbalanced, you can end up with microbial dysbiosis. Dysbiosis is linked to a wide range of health conditions, including:

Gut microbiome health has also been linked to brain function and mental health. Conversely, mental well-being factors, such as psychological stress, can have negative repercussions on gastrointestinal microbiota.

Visit the PrimeHealth store for medical grade, third-party tested, evidence-based probiotics. We highly recommend: 

How to Maintain a Healthy Gut

Fortunately, there are plenty of natural ways to help maintain a healthy gut and even heal an unhealthy gut. Whether you want to prevent gastrointestinal issues or reverse them, here are a few steps you can take to get started:

Neurotransmitter Production in the Gut

Neurotransmitters are chemicals that help regulate numerous bodily functions. Imbalances in neurotransmitter levels have been associated with neurological disorders like depression. 

You’re probably already familiar with some neurotransmitters, like serotonin and dopamine. Serotonin is largely associated with mood and happiness. But did you know that serotonin, dopamine, and several other neurotransmitters are produced in your gut?

Here are some of the major neurotransmitters produced in the gut:

Hormone Production in the Gut

Our bodies regulate hormones through our endocrine systems. Hormones impact our growth, sexual function, and mood, as well as help us regulate appetite. Having certain bacteria in our gut microbiota can impact hormone release in the gut.

Some of the hormones influenced by our gut bacteria include:

How Mental Health Can Alter Digestion

Mental health disorders and digestive issues often go hand-in-hand. Those dealing with irritable bowel syndrome (IBS), for instance, are significantly more likely to experience symptoms of depression or anxiety.

It may seem obvious that dealing with gastrointestinal disorders might lead to stress. However, the relationship goes both ways through what is called bi-directional communication. Poor mental health can also cause gut dysbiosis and a host of related problems. 

Here are some of the digestive symptoms that stress can cause:

  • Gas
  • Bloating
  • Abdominal pain
  • Constipation
  • Diarrhea

Initially, the body’s stress response is adaptive. The release of cortisol and adrenaline helps us address threats and trauma. This response, however, is intended to be short-term. 

While normally helpful, the stress response becomes unhealthy when stress is frequent or consistent over extended periods (chronic stress).

Chronic stress is a major cause of both mental and physical problems. It is linked to anxiety and depression and disrupts homeostasis, leading to a variety of gastrointestinal disorders

In fact, the effects of prolonged stress in the body are connected to 80% of health disorders, including physical, neurological, and psychological.

That’s not all. The neurological pathways activated in response to physical pain overlap heavily with the pathways activated in response to social or emotional pain. This suggests that physical and psychological stress may produce similar physiological responses. 

Perhaps this is a factor in the two-way street between stress and digestive issues. Fortunately, it also means that there may be more treatment options for any one condition than traditionally thought. 

Can Behavioral Treatment Help With GI Disorders?

Behavioral treatments such as cognitive behavioral therapy (CBT) are generally associated with mental health. However, recent research shows that CBT can help reduce symptoms of IBS. In fact, implications for behavioral treatment of gastrointestinal disorders have led to an entirely new field of medicine called behavioral gastroenterology.

Behavioral gastroenterology explores psychological and lifestyle factors that may impact digestive health. Treatment options may include CBT, hypnotherapy, and meditation, as well as dietary and other lifestyle changes.  

Dietary modification plays a major role in treating GI disorders. With dysbiosis so heavily linked to illnesses, following a dysbiosis diet may significantly improve gastrointestinal health. This may include removing foods that contribute to dysbiosis and adding gut-healing foods, probiotics, and prebiotics.


How do I fix my gut-brain connection?

Fix your gut-brain connection by adopting a diet rich in probiotics and prebiotics, engaging in regular physical activity, practicing stress-reduction techniques like meditation, and considering vagus nerve stimulation exercises.

What are the symptoms of an unhealthy gut?

Symptoms of an unhealthy gut include digestive issues like bloating, gas, diarrhea, or constipation, as well as mood swings, fatigue, and difficulty sleeping.

Is the gut-brain connection involved in autism?

Yes, research suggests that the gut-brain connection plays a role in autism, with studies showing altered gut microbiomes in individuals with autism, which may affect behavior and cognitive functions.

What are the worst foods for gut health?

The worst foods for gut health typically include processed and high-sugar foods, artificial sweeteners, and foods high in saturated fats, which can promote inflammation and dysbiosis.

What is the gut microbiome?

The gut microbiome refers to the trillions of microorganisms, including bacteria, viruses, fungi, and other microbes, living in the digestive tract, which play crucial roles in digestion, immune function, and overall health.

What role does the vagus nerve play in the gut-brain connection?

The vagus nerve facilitates communication between the brain and the gut, transmitting signals in both directions and playing a key role in regulating digestive processes, mood, and immune responses.

How can you strengthen the gut-brain connection?

Strengthen the gut-brain connection by consuming a balanced diet rich in fiber, fermented foods, and omega-3 fatty acids, staying hydrated, getting enough sleep, exercising regularly, and managing stress effectively.

We’re Here to Help

Our team of providers at PrimeHealth specializes in the gut-brain connection for whole-body wellness. We love educating our patients and developing individual treatment plans to cure health conditions at the root, rather than just treating the symptoms.

Schedule your free consultation today to learn if we can help you, too.


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