Did you know that there is a literal connection between your brain and your gut? Believe it or not, there’s a special line of communication that the brain and the gut use to message each: it’s called the Vagus Nerve, and it plays an important role in managing stress. Today’s post is going to be all about this special nerve, and what you can do to keep in working order. Let’s get right into it!

Getting to the Know the Vagus Nerve

The Vagus Nerve starts from the brainstem and reaches all the way down to the intestines. While this is its main connection, the Vagus Nerve also branches out towards other areas like the throat, esophagus, lungs, heart, and diaphragm. A nickname for the Vagus Nerve is the “Wandering Nerve” because of how it “wanders” down from the head to the gut. It acts sort of like the captain of our nervous system, helping the organs and areas it reaches to communicate with one another and perform their essential functions. But the main system the Vagus Nerve is closely a part of is our Parasympathetic Nervous System,which is responsible for regulating our body’s ability to “rest and digest”. (For more information on the Parasympathetic Nervous System, as well as the Sympathetic Nervous System, read my post here.) [1]

A Closer Look at the Vagus Nerve

Think of the Vagus Nerve as a highway between the brain and the gut. The messengers that cross between the two are neurotransmitters. There are two in particular that play important roles in digestion: GABA, which blocks our brain’s response to stress and regulates gut activity, and acetylcholine, which activates the digestive process turns off the body’s response to stress by slowing down heart rate and increasing blood flow towards the gut. Next to GABA and acetylcholine, the Vagus Nerve and both the gut and brain also use serotonin, dopamine, and norepinephrine).

Putting it all together, the Vagus Nerve is a wandering nerve that extends from the brain down into the intestines, along with other organs, enabling them to communicate with each other. Its major function, however, is its ability to inform the body on how to respond to stress, playing an active role in its transition between “fight or flight” during stress to “rest and digest” outside of that. [2] [3]

Other Functions

Aside from managing the body’s stress response, the Vagus Nerve also benefits both our health and digestion in a number of ways, including:

• Motility: Motility is the movement of material in and out of our digestive tract- aka, bowel movements. (Low motility is a sign of constipation, and fast motility is a sign of diarrhea.) The Vagus Nerve regulates motility by sending signals from the brain to the stomach and bowels; if we’re under stress, it acts as a phone line of communication, telling our gut that going to the bathroom is not as important as the stress or perceived danger at hand. On the flipside, our stomach can also tell our brain that stress is taking place, which again can also impact how fast or how slow our motility is. As a bonus, because of stress’s impact on heartburn, GERD, and other gut-related disorders, the Vagus Nerve also plays a role in both the development and worsening of all of these issues. [4]
• Appetite: The Vagus Nerve helps to regulate our appetite by telling the brain when we’re full. During meals, our stomach naturally distends from the food we consume. This distention activates specific receptors that send signals back to the brain through the Vagus Nerve. [5]
• Nutrient Absorption:We also need the Vagus Nerve to help us fully absorb nutrients, especially Vitamin B12. A great deal of this micronutrient is absorbed in the stomach. Here’s where the Vagus Nerve comes in: it causes stomach cells to release both acid and intrinsic factor, the latter being what the body needs in order to absorb B12. Many studies have shown that B12 absorption becomes impaired after the Vagus Nerve is cut. [5] [6]
• Managing Inflammation: Another function of the Vagus Nerve is its activation of the “inflammatory reflex”. This kicks into gear during stress, when stress-hormones like cortisol are detected. Once they’re found, the Vagus Nerve communicates with the immune system in the gut and tells it to release histamines, which create an inflammatory response in order to prepare the gut for battle against potential “bad guys”. If there isn’t any danger, the Vagus Nerve will then release neurotransmitters that trigger an “anti-inflammatory” response and lower the inflammation. Without the Vagus Nerve, our body can remain stuck in an inflammatory cycle even when the stressor or infection has been dealt with. This is what’s known as chronic inflammation, and it’s associated with conditions like Inflammatory Bowel Disease (IBD). Studies once again have shown that, once again, when the Vagus Nerve is cut, the symptoms of gut conditions like IBD worsen. [7] [8] [9]

Vagal Tone 101

It’s no wonder why this “Wandering Nerve” is a powerful player in our overall health and digestion. But did you know that like a muscle, the Vagus Nerve could either be weak or strong? This level of strength is referred to as Vagal Tone, or rather, the overall activity of the Vagus Nerve.

Signs of a healthy, strong Vagal Tone include:

• Being able to bounce back from stress
• Maintaining a healthy appetite
• Regular, healthy bowel movements
• Overall, having a general sense of well-being
• Both a good heart rate and heart rate variability (both of which ultimately determine how well your Vagal Tone is!)

[10] [11] [1] [2]

With these in mind, the oppositecan be said for Low Vagal Tone. These include inflammation, poor mood (such as depression, loneliness, or anxiety), high blood pressure and heart rate, heart attacks, and, possibly, stroke. A good point to mention though is that when it comes to our Vagus Nerve, the keyword towards achieving a strong Vagal Tone is balance. Too low of a tone is obviously going to result in the issues I just mentioned but having a Vagus Nerve that is over stimulated can potentially result in problems like reflux, irregular stools, bloating, elevated cortisol, poor absorption or deficiencies of Vitamin B12, shortness of breath, low stomach acid, IBS, poor satiety from eating, anxiety, and hiccups. [12] The common culprits behind weak Vagal Tone include chronic inflammation, stress, improper breathing techniques, alcohol, and poor nutrition (especially in diets high in processed seed oils and trans fats). [13] [14] [15]
Luckily, there are many things that can be done to both strengthen and maintain the Vagus Nerve:

• Deep Breathing (this is why it’s important to breathe better during workouts!)
• Meditation
• Cold Plunges or Showers
• Inversions (ever heard of Inversion Therapy?)
• Laughter, singing, chanting, and humming (bonus: gargling has been shown to stimulate the Vagus Nerve!)
• Stress reduction

[12] [16] [17] [18]

Ultimately, keeping your Vagus Nerve healthy boils down to your lifestyle. It’s not just what you eat, it’s how you eat, and how you live. While stress is unavoidable, what is within our control is the way in which we choose to deal with it. In a sense, it’s how we choose to feed it. If we allow our stress to become chronic, then it will no doubt affect the function of our Vagus Nerve, which then impacts our digestion, mood, and ability to lower inflammation. Taking care of the Vagus Nerve doesn’t require an expensive supplement regimen or exotic biohack. Simple things like deep breathing, meditation, and staying positive rather than tense can all keep the stress from becoming chronic.

So, the next time you’re anticipating stress, why not take a few deep breaths, and give thanks to the Wandering Nerve that keeps our digestion in great shape?

Sources:

[1] http://www.meddean.luc.edu/lumen/meded/grossanatomy/h_n/cn/cn1/cn10.htm
[2] https://www.medicalnewstoday.com/articles/318128.php
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5859128/
[4] http://www.vivo.colostate.edu/hbooks/pathphys/digestion/stomach/motility.html
[5] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5337130/
[6] https://www.caam.rice.edu/~cox/wrap/vagusnerve.pdf
[7] https://www.psychologytoday.com/us/blog/the-athletes-way/201607/vagus-nerve-stimulation-dramatically-reduces-inflammation
[8] https://gut.bmj.com/content/62/8/1214
[9] https://www.healthline.com/human-body-maps/vagus-nerve
[10] https://www.ncbi.nlm.nih.gov/pubmed/1513615
[11] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5316555/
[12] https://www.saragottfriedmd.com/viva-las-vagus-how-vagal-tone-impacts-your-health-and-10-ways-to-%E2%80%8Eimprove-it%E2%80%8E/
[13] https://psychology-spot.com/vagus-nerve-disorders/
[14] https://www.ncbi.nlm.nih.gov/pubmed/10609983
[15] https://www.huffpost.com/entry/how-a-high-fat-diet-may-be-screwing-with-your-brain_n_55a417d7e4b0ecec71bcb352
[16] https://www.psychologytoday.com/us/blog/the-athletes-way/201302/the-neurobiology-grace-under-pressure
[17] https://www.ncbi.nlm.nih.gov/pubmed/3159265
[18] https://www.wimhofmethod.com/vagus-nerve-stimulation