Your Guide to the Vagus Nerve
With recent news on long Covid, the vagus nerve is about to finally get the respect it deserves.
New research is showing that longer-term issues may be due to damage or dysfunction at this critical hub.
Our original interest in the vagus nerved stemmed from the uncanny ability of the gut to control function in the brain.
The gut operates like a thermostat for inflammation and the brain picks up on this.
The microbiome (gut bacteria makeup) actually drives a great deal of function in our brain but this begs the question…how?
Hello Vagus Nerve!
Then there's the connection with acetylcholine, the secret star for mental health.
So let's get introduced to these areas:
- The vagus nerve - hub between our two brains
- Vagus nerve as main site of acetylcholine production
- The vagus nerve cardiovascular conduit
- Ways to support the vagus nerve
Let's get started!
The vagus nerve - hub between our two brains
Outside of our brain, most neurons in the body…are in the gut!
It's termed the enteric nervous system as a result.
So why all this "brain power" in our gut?
First, it manages the complex gut process without any input from our central nervous system:
The enteric nervous system is the largest and most complex unit of the peripheral nervous system, with ~600 million neurons releasing a multitude of neurotransmitters to facilitate the motor, sensory, absorptive, and secretory functions of the gastrointestinal tract.
That isn't to say we lack communication between the two brains.
You can think of the brain as sensing the outer world and the gut as sensing the internal world.
Our interest is how issues in the gut can manifest in the brain.
How does a gut bacteria like akkermensia trigger positive mental health benefits?
Why are gut inflammatory states so tied to mental health issues?
Scientists can literally transfer fecal bacteria and drive mental health improvements:
All studies found a decrease in depressive and anxiety-like symptoms and behaviors resulting from the transplantation of healthy microbiota.
And vice versa (make mental health worse if transferred from people with issues).
This is fascinating! We did a deep dive on probiotics and anxiety or neuroinflammation for the two poles but what about in the middle?
The vagus nerve is a major signaller of inflammation both ways!
Treatments that target the vagus nerve increase the vagal tone and inhibit cytokine production. Both are important mechanism of resiliency
Cytokines are the little assassins of inflammation.
The next statement in that study is interesting…
Both are important mechanism of resiliency
We have a big guide on tools for resilence.
So, what's the connection between the vagus nerve and mental health?
The stimulation of vagal afferent fibers in the gut influences monoaminergic brain systems in the brain stem that play crucial roles in major psychiatric conditions, such as mood and anxiety disorders
Okay..let's break that down because it's too important.
When you stimulate the vagus nerve, it leads to the production of key neurotransmitters like serotonin and GABA in the brain!
Serotonin is our master mood and stress manager as well as the governor of all human behavior (target of SSRIs till they build tolerance).
GABA is our brain's "brake" pedal and key to anxiety, insomnia, pain, and a range of issues.
So, we have inflammation (cytokines) and neurotransmitters under the control of the vagus nerve.
That's just the surface level…let's go deeper.
Loosely speaking, the vagus nerve is our connection to our own inner world.
Interoception is the technical term.
"Gut sense" is the more common version.
The vagus nerve is the main pathway for conveying information about the internal condition of the body to the brain.
Why would evolution wire this two-way communication?
If something is "wrong" in the body, we get a sense of anxiety or panic. This is a way of the body to communicate to our brain on its state. Anxiety is a logical response!
This is especially true with infection or pathogens in the gut. Nausea. Quickened heartbeat. Anxiety.
All vagus nerve!
We usually attribute feelings of love or even fear to our heart but the heart is just a muscle. Right below the breastplate, the lower end is the vagus nerve and that's what you're really feeling.
Let's introduce the primary operator in the vagus nerve which is just as fascinating.
Vagus nerve as the main site of acetylcholine production
You're going to want to get to know acetylcholine.
The original discovery of the vagus nerve noted that when stimulated, it releases acetylcholine.
We did a deep dive on acetylcholine here but a few quick takes.
First, it's a primary player in the parasympathetic nervous system. This is the rest and digest side.
The opposing force to our fight or flight system (which runs on adrenaline).
Acetylcholine is best described as "Calm and Focused".
It is THE player for ADHD (despite all the amphetamines handed out) and critical for dementia and just about every mental health issue out there.
Nicotine mimics acetylcholine at the same receptor and voila, millions of daily users.
One note…early trauma or infection can downregulate acetylcholine later in life by damaging the vagus nerve.
See our review on early trauma here.
Our focus here is on the stress response. Remember the "resilience" part from above?
A low vagal tone means the vagus nerve isn't functioning as it should. This may lead to a heightened stress response which becomes chronic, possibly resulting in depression, anxiety, gut issues and inflammation
This makes sense…remember the opposing force to acetylcholine is adrenaline and we all know how that feels.
It's literally enmeshed with stress response!
Low vagal tone just means reduced baseline levels of acetylcholine.
What can damage the vagus nerve?
The usual suspects:
- Infection (especially viral)
- Chronic gut inflammation
- Certain diseases where states are imbalanced for prolonged periods of time (diabetes)
We'll look at ways to support the vagus nerve below.
Let's first take a detour.
The vagus nerve cardiovascular conduit
The vagus nerve has "feelers" out to all the organs but one is very close by (and close to heart)??
Its name literally come from the root word "wanderer".
This is where all the hub bub is around covid (especially long covid).
New research to be presented at this year’s European Congress of Clinical Microbiology and Infectious Diseases (ECCMID 2022, Lisbon, 23-26 April) suggests that many of the symptoms connected to post-COVID syndrome (PCC, also known as long COVID) could be linked to the effect of the virus on the vagus nerve
There were some specific clues to vagus nerve involvement such as weakened voices (vagus controls the larynx), gut issues, and brain fog (see brain fog).
This brings us to the heart!
One clear symptom with long covid is tachycardia…a racing heart.
Look at the result of slowing vagus function there:
These branches stimulate a reduction in the resting heart rate. They are constantly active, producing a rhythm of 60 – 80 beats per minute. If the vagus nerve was lesioned, the resting heart rate would be around 100 beats per minute.
In fact, just look at the beta-blockers effect:
beta-Blocker therapy increased cardiac vagal activity, as shown by measures of high-frequency heart rate variability and reflex studies.
So…where does the damage start?
Best to look to the gut! After all, this is where viruses, bacteria, and other pathogens gain entrance and establish an inflammatory foothold.
The mouth, nose, and other entry points also figure (hence the tie between gum disease and heart disease).
The fact that can you can drop heart rate by just stimulating the vagus nerve is fascinating. Let's go there now.
So…how can we support a powerful network hub which drives how we feel inside?
Ways to support the vagus nerve
By stimulating the vagus nerve, recent studies have shown pretty remarkable results from conditions spanning from depression to arthritis.
Supporting the vagus is where things get interesting. Even bizarre.
First, calm the storm. This means addressing gut issues specifically and inflammation more generally.
In that corner:
We have massive reviews via the links above on all of these but the things they have in common:
- Calm gut inflammatory states
- Stress response buffers
- Protects gut barrier
We can't improve vagus nerve tone if it's constantly under assault and the immune system is front and center since the vagus nerve is a primary inflammation "news" hub.
What about direct support of this pathway directly?
- CDP choline
- CBD isolate
Choline is our dietary choline (eat your eggs) and it's impressive for supporting this system.
Acetylcholine deficiency is really a big driver of dementia hence the increased risk from the "anti" class of meds (anti-acids, anti-histamines, etc).
Choline is a great way to support while you calm the storms above.
CBD isolate is able to stimulate the vagus nerve via the TRPV channel.
We found CBD exhibited direct excitatory effects on vagal afferent neurons that required TRPA1, were augmented by TRPV1,
This makes sense since many of the effects from CBD mirror what we described above for acetylcholine (calm, anti-epileptic, etc).
Okay…now, let's get to the broader ways to support vagal tone.
The vagus nerve is right behind the lower, chest plate. As a result, any action on that area will stimulate it. Also, the throat since it connects there robustly (controls swallowing, talking, etc).
- Deep breathing
- Tapping (and vibration) on the lower chest plate
No wonder those all feel good. Remember, calm and focused.
It gets more interesting though.
- Cold exposure
- Deep breathing (especially expand your stomach on intake and long... LONG out-breath)
One note…research shows that the breathing out duration is key to parasympathetic nervous system activation. That's the vagus nerve!
Hence the 4-6-8 (4 breath in; 6 hold; 8 breath out).
Okay…it all intuitively makes sense. Now to the bizarre.
Other tricks to stimulate the vagus nerve seem strange at first:
- Saying "Thank you"
- Giving compliments
- Showing appreciation
We've known for a while from research that a mindset of gratitude can not only positively benefit mental health but ALSO…physical health.
We may know why now.
But why did evolution hardwire this into us? Especially for an internal sensor?
Perhaps it's to drive the "tribe" support mechanism so we work together. After all, we are social animals and we would fare pretty badly on our own out there in the savannah.
Maybe acetylcholine signs the social contract!
We'll leave this to future studies but a sense of gratitude and kindness seems to be baked into the cake for our internal health.
The net-net is this…
A higher vagal tone index is linked to physical and psychological well-being. Conversely, a low vagal tone index is associated with inflammation, depression, negative moods, loneliness, heart attacks, and stroke.
So…physical and psychological well-being. If you're into that.
Be well! Thank you!! (I can feel the acetylcholine coursing now)
Always work with a doctor or naturopath with any supplement!
The information provided here is not intended to treat an illness or substitute for professional medical advice, diagnosis, or treatment from a qualified healthcare provider.