How Trauma and Stress Affect Gut Health

Did you know that trauma and gut health are connected? This may come as no surprise since your gut is connected to almost every system in your body. In fact, gut health is related to your immune system, metabolism, hormones, thyroid, adrenals, skin, and even your brain and mental health. 

This is why the gut is often the root cause of so many chronic conditions like autoimmune diseases, skin disorders, estrogen dominance, hypothyroidism, and even mental health issues(1). 

Gut dysbiosis and gut inflammation have been linked to several mental illness. These include anxiety and depression, but also autism spectrum disorder and neurodegenerative disorders like Alzheimers and dementia.

The Gut-Brain Axis: How the Gut Microbiota Can Bidirectionally Communicate With the Brain (2)

One of the ways the gut and the brain communicate is through the vagus nerve. 

The vagus nerve is a bundle of nerves leading from the gut through the heart and to the brain. In short, the vagus nerve IS the mind-body connection. 

In fact, the word “vagus” means “wanderer” in Latin. This accurately represents how the nerve wanders all over the body and reaches various organs.  

If you picture the information moving in the body as a network, about 80% of it moves up from the body to the brain. And, only about 20% of the traffic moves from the brain to the body. That is a lot of traffic, and the vagus nerve handles the majority of it!

The main function of the vagus nerve is to power the body’s parasympathetic nervous system.

The parasympathetic nervous system is part of the autonomic service system known as the “rest and digest” system. It works in the body to: 

  • Decrease heart rate and respiration 
  • Decrease stress hormones 
  • Trigger the release of oxytocin and serotonin
  • Decrease blood pressure (3)  

Specifically in the gut, it works to:

  • Increase blood flow to the digestive system 
  • Release neurotransmitters, such as acetylcholine, that regulate muscle contractions (therefore increasing mobility in the gut)
  • Increase gastric secretions of pancreatic enzymes and bile 
  • Decrease inflammation 
  • Strengthen the gut barrier function 

This all happens through the CNS communication via the vagus nerve. And, all of these functions are important for supporting optional digestion and mood. 

How Are Trauma and Gut Health Connected?

When we are in a state of stress, our body’s sympathetic nervous system is activated. This prepares the body to either fight, flee, or in some cases, freeze. When we are in a sympathetic response, the vagus nerve is inhibited, so the body can work to: 

  • Increase heart rate and respiration
  • Increase blood pressure 
  • Decrease blood to the digestive tract and reproductive organs 
  • Increase blood to muscles, lungs, and other areas essential for moving away from the perceived danger 
  • Release stress hormones, like cortisol, and neurotransmitters, like epinephrine (adrenaline), to make us stronger and faster 
  • Release glucose rapidly for quicky burning and energy

Basically, your digestive system completely shuts down in response to stress and trauma. Inflammation is increased and stress hormones like cortisol are released.

This is why the vagus nerve is such a crucial part of healing. It helps the body stay more in a parasympathetic or “rest and digest” state. But what you really need to pay special attention to is the “tone” of your vagus nerve.

Vagal tone is an internal biological process that represents the activity of the vagus nerve. 

Increasing your vagal tone activates the parasympathetic nervous system. Having higher vagal tone means that your body can relax faster after stress.

Researchers have discovered that there is a positive feedback loop between high vagal tone, positive emotions, and good physical health. In other words, the more you increase your vagal tone, the more your physical and mental health will improve, and vice versa (5).

“It’s almost like yin and yang. The vagal response reduces stress. It reduces our heart rate and blood pressure. It changes the function of certain parts of the brain, stimulates digestion, all those things that happen when we are relaxed.”  — Dr. Mladen Golubic, MD, Medical Director of the Cleveland Clinic

How to Strengthen Your Vagal Tone 

1. Cold water therapy:

Researchers have found that exposing yourself to cold on a regular basis can lower your sympathetic “fight or flight” response and increase parasympathetic activity through the vagus nerve (6).

For a long time, I did cold showers until I recently purchased a cold-plunge. This took my cold water therapy to the next level.  If you follow me on Instagram, you have likely seen some of my stories and posts of me doing an ice bath. 

Essentially, cold stimulation triggers peripheral vasoconstriction, making your body work harder to keep warmer by shifting the blood volume towards the core. The resulting increase in central pressure activates the baro-reflex. This is responsible for reducing sympathetic nervous activity while shifting the autonomic heart rate towards parasympathetic dominance. You can trigger this response by:

  1. Cold showers
  2. Cold-plunge/ ice baths 
  3. Splashing cold water on your face

2. Diaphragmatic Breathing:

Most people take about 10 to 14 breaths each minute. Taking about 6 breaths over the course of a minute is a great way to relieve stress. You should breathe in deeply from your diaphragm. When you do this, your stomach should expand outward. Your exhale should be long and slow. 

Diaphragmatic breathing has been shown to reduce anxiety and increase the parasympathetic system by activating the vagus nerve (7, 8).

3. Meditation and Chanting:

My first introduction to meditation was through Dr. Joe Dispenza and his book “Breaking the Habit of Being Yourself.”  Dr. Joe says, “the word meditation means to become familiar with.” As you become familiar with the thoughts, feelings, and behaviors of the old self, you begin to rewire and condition the brain to a new self. 

It’s through meditation that we can enter the subconscious (you can think of the subconscious as the brain’s operating system) to change our unwanted programs. By dropping into the operating system of the brain, we can alter habits, behaviors, and remove emotional scars. 

There are multiple studies showing that meditation has the power to reduce sympathetic response, increase vagal tone, and promote feelings of wellbeing. (9, 10, 11) 

“OM” changing, often done during some meditation practices, has also been shown to stimulate the vagus nerve. (12) 

You can get my personal meditation playlist here and The Oneness Om song you can listen and follow along with here

4. Probiotics:

Your gut bacteria play a HUGE role in your brain function through the production of serotonin and stimulation of the vagus nerve (13).

A 2011 study performed by Farncombe Family Digestive Health Research Institute demonstrated that the probiotic Bifidobacterium longum (practitioner code Z47 to order) normalized “anxiety-like behavior and hippocampal brain derived neurotrophic factor (BDNF) in mice with infectious colitis” by decreasing stress hormones and activating the vagus nerve (14).

Another study found that animals given the probiotic Lactobacillus Rhamnosus induced positive changes to GABA receptors in the brain, the main CNS inhibitory neurotransmitter. They also found a reduction in stress hormones, leading to reduced depression and anxiety. 

The researchers also concluded that these beneficial changes between the gut and the brain were facilitated by the vagus nerve. When the vagus nerve was removed in other mice, the addition of Lactobacillus Rhamnosus to their digestive systems failed to reduce anxiety, stress, and improve mood (55). 

Both Lactobacillus Rhamnosus and Bifidobacterium Longum are included in the Ther-Biotic Complete supplement. You can use my practitioner code Z47 to create an account and order. 

If you are curious as to what probiotics your gut-microbiome may be deficient in, this is part of the testing we offer with our Functional Wellness Coaching

5. Choline

In order for the vagus nerve to successfully transmit messages, it relies on its main neurotransmitter, acetylcholine (ACh). ACh can also reduce inflammatory cytokines and improve memory and focus.

Choline is an amino acid that is a precursor to ACh and is necessary to generate it. Animal studies have shown that choline ameliorates cardiovascular damage by improving vagal activity. But, it is also involved in muscle control, memory, and mediation of emotion and behavior in the brain (16). 

Essentially, it is crucial for proper CNS functioning and promoting vagal tone. 

Here are the top 10 food sources highest in choline that I recommend including in your diet: 

  1. Whole eggs
  2. Organ meat 
  3. Caviar 
  4. Fish 
  5. Shiitake mushrooms 
  6. Grass-fed beef
  7. Pastured chicken and turkey 
  8. Cruciferous vegetables, like cauliflower, broccoli, and Brussels sprouts 
  9. Almonds
  10. Red potatoes 

You can also take a Phosphatidylcholine supplement with advanced liposomal delivery for increased absorption and utilization (Quicksilver Scientific discount rachel20)

6. Omega-3 fatty acids

Omega-3 fatty acids are essential fats that your body cannot produce on its own and are one of the few fats that can cross through the blood-brain-barrier. Studies have shown that omega-3 fatty acids increase vagal tone and vagal activity (17). 

Omega-3 fatty acids are highly concentrated in fish. Furthermore, high fish consumption has been shown to be associated with “enhanced vagal activity and parasympathetic predominance” (18). 

Here are the top 10 food sources highest in Omega-3 fatty acids that I recommend including in your diet: 

  1. Mackerel 
  2. Salmon 
  3. Cod liver oil 
  4. Herring 
  5. Sardines 
  6. Anchovies 
  7. Caviar
  8. Flaxseed
  9. Chia seeds
  10. Walnuts

You can also take an Omega-3 EPA-DHA supplement daily, like this one here

7. Zinc

Zinc is a mineral that is essential for the gut-brain connection via stimulation of the vagus nerve. It also has the ability to modify the tight junctions of the intestinal lining, helping to limit intestinal permeability (aka leaky gut). (19, 20) 

Most people aren’t getting enough zinc, which can greatly affect their mental health. 

Here are the top 5 food sources highest in zinc that I recommend including in your diet: 

  1. Animal protein
  2. Shellfish 
  3. Seeds
  4. Nuts
  5. Eggs

8. Social Connection and Laughing

Research shows that human connection and positive emotions positively influence vagal tone (24). 

Love and connection is a human need for survival. This explains why children who suffer from abandonment or inconsistent attachment from their mothers have shown to shape negative health outcomes later in life through alterations to the body’s stress response (22, 23).

The good news is that it has also been shown that these changes aren’t permanent. “Our brain continues to be plastic throughout our lives. Maladaptive circuitry can certainly be molded by later enrichment, interventions, and treatments” (25).

9. Exercise

Fitness has been shown to have many positive benefits for not just physical health but also mental health and mood through stimulation of the vagus nerve (26). 

Many experts have recommended exercise as the number one approach for optimal brain health. Checkout this podcast I recorded on this topic here with Louisa Nicola, the CEO of Nueroathletics. 

This is my exercise routine:

  1. Lift heavy weights 4x per week 
  2. Daily stretching and yoga for 15 minutes
  3. 60-minute walks outside on the days I am not lifting weights

How Cortisol Affects Gut Health

Leaky Gut

Over time, chronically high cortisol causes low grade inflammation and also makes you catabolic. The body begins to break down muscle tissue and the gut lining, leading to intestinal permeability. Now, bacteria, food and toxins can enter the bloodstream and cause a systemic immune and inflammatory response.

Studies have also shown that a leaky gut contributes to a leaky brain, where we get a breach in the blood brain barrier. Toxins can also pass through, leading to symptoms like brain fog, anxiety, or depression.

Bacteria overgrowth

Bacteria overgrowth, or SIBO, is also a common symptom of having your sympathetic state chronically activated. Your digestive system shuts down, your body suppresses the production of digestive enzymes and bile, and motility comes to a halt. 

This creates a perfect terrain for bacteria to over grow in the small intestine. Not to mention, the number one vice people turn to when they’re stressed is food and alcohol. These can further contribute to bacterial overgrowth and a leaky gut. 

How Trauma Affects Gut Health

The way in which we relate to ourselves today (the way we think, feel, and view ourselves) was established from our earliest relationship: our parents. 

We talked about how essential love and connection is for survival earlier. When there is a lack of nurturing through emotionally unavailable parents, inconsistent love, and even insensitive and dismissive parents, it creates an imprint or memory on our nervous system at a very early age. 

When we have a history of trauma that has not been addressed, the body often lives in what I call a “hyper-aroused” state. This is where the body can get “stuck” in this sympathetic (fight/flight) state, leading to poor vagal tone. 

The body is subconsciously always on high alert looking for perceived threats and danger. 

This automatic response happens due to a couple of changes that take place in the nervous system and brain: 

The Vagus Nerve

When we are “triggered”, meaning something happens in the present that brings the CNS back to the memory of the first perceived threat, the body responds by activating the sympathetic nervous system. 

The vagus nerve is involved in this process of retaining memories. In a study published in the Journal of Translational Medicine, scientists found rats’ ability to retain spatial and fear-based memories (created to protect them from previous negative outcomes) was strengthened with the electrical stimulation of their vagus nerve (4). 

The Connections Between the Prefrontal Cortex and Amygdala

In a recent paper, researchers found that female rats, in particular, developed abnormal connections between amygdala and the prefrontal cortex part of the brain in response to neglect (23) 

The amygdala may be best known as the part of the brain that drives the so-called “fight or flight” response. In contrast, the prefrontal cortex is best known as the part of the brain that is involved in decision making, impulses, and self-control. 

“When you see something that might be a threat (say, a tiger), your amygdala fires off signals to several areas of the brain, including the prefrontal cortex, indicating that you should be frightened. The prefrontal cortex responds by integrating information from other areas of the brain, like context clues (The tiger can’t reach us.) or prior memories (This is a zoo. We’ve been to a zoo before.), and signals the amygdala to, essentially, calm down)” (25). 

This leads to maladaptive behaviors, where you start to see increasing anxiety-like behaviors even in the absence of something that could be anxiety-provoking. 

The disruption of both the vagus nerve and the connection between the amygdala and prefrontal cortex part of the brain are just two of the ways that trauma affects the body’s stress response later in life. 

Functional Medicine For Gut Health and Healing

The information in this article is why I believe in holistic healing and why the whole person must heal for the gut to function optimally. But also, the whole person must heal for optimal health and well-being.

Healing is possible when we can fully address the root cause(s) and create an effective treatment plan. This combines proper nutrition, exercise, therapy, and functional medicine lab testing to look at the different body systems where there could also be other hidden imbalances with things like the gut microbiome, hormones, thyroid, blood sugar, inflammation, toxins, and micronutrients





























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