Everything You Wanted To Know About The Vagus Nerve And How It Affects Your Bone Health
The nervous system is the central portal to all body systems, including your bones. The process of bone remodeling cannot take place unless the appropriate signals are sent along the nerves to regulate the process.
As a part of the autonomic nervous system, the vagus nerve is the “head honcho” of involuntary biological processes. It stimulates and sends feedback from the organs in the abdominal cavity, plus it regulates involuntary actions like mood, digestion, stress response, and so forth. The vagus nerve is also largely responsible for activating the production of cortisol, the stress hormone that damages bone when levels are chronically high.
To stimulate the vagus nerve and “set things right” again, you can employ the Valsalva maneuver, which is easily performed anywhere, any time. It’s so effective that it’s used in medical practice as a treatment for depression.
So let’s take a look at this “wandering” nerve, how it affects your health and your bones, why the Valsava maneuver works, and how to perform it.
The Vagus Nerve In A Nutshell
The word “vagus” is derived from the Latin word vagary, meaning “to wander.” This is also where we get words like “vagrant” and “vagabond.” It signifies a meandering pathway that is not anchored in an obvious way, unlike the contained nerves in the spinal cord. But even though this nerve appears to wander, it’s not random in its pathway.
The vagus nerve originates in the brain stem – it’s actually the tenth cranial nerve – and travels up to the eyes and down through the chest and abdominal cavity. It branches off in various places along the way, innervating the pupils, esophagus, lungs, digestive organs, bladder, kidneys, reproductive organs, and much more. It’s the longest cranial nerve in the body, and it’s also one of the most important.
In fact, the vagus nerve is the most vital element of the parasympathetic nervous system, or PNS, which works in opposition to – and also in conjunction with – the sympathetic nervous system, or SNS.
The PNS is responsible for maintaining homeostasis in the body’s various systems. A good way to think of the PNS is as the “rest and digest” nervous system. It decreases heart rate, constricts bronchial tubes, relaxes muscles, and increases the secretion of digestive juices and saliva.
The SNS controls the way the body reacts to danger and acute stress (the automatic “fight or flight” response). It tightens muscles, dilates the bronchial tubes, releases adrenaline, converts glycogen to glucose for fast and quick energy to the muscles, and increases heart rate.
As the major “boss” of the PNS, the vagus nerve calms your body down after a SNS-instigated fight-or-flight response. Once the stressor has passed, the vagus nerve brings the body back to a state of mental and physical balance and calm.
The vagus nerve does all that and a whole lot more.
Seven Ways The Vagus Nerve Affects Your Health And Your Bones
Here are seven of the many ways this wandering nerve is involved in your health.
1. Regulates Heart Rate
The vagus nerve actually controls your heart rate by stimulating the sinoatrial node of the heart to release acetylcholine, a hormone that slows down the heart rate. The relationship between the vagus nerve and the heart is so reliable, that doctors can test the vitality of your vagus nerve (and the variability of your heart rate) by timing and charting the moments between heart beats.
2. It Can Cause Fainting When Over-Stimulated
If you feel light-headed (or actually pass out) when you see blood or observe medical procedures, it’s not a sign of weakness. Instead, it’s a phenomenon known as “vagal syncope,” a response to stress that over-stimulates the vagus nerve. As noted in the first point, the vagus nerve is closely connected to your heart, so when it’s over-stimulated, it can cause your heart rate to drop and your blood pressure to drop. The blood flow to your brain is then restricted, causing you to feel faint.
3. Improves Memory
Animal studies show that vagus nerve stimulation improves memory.1 This is likely due to the fact that the vagus nerve releases norepinephrine into the amygdala, the area of the brain that organizes and consolidates memories and emotions.
4. Sends Messages To And From The Brain And The Gut
Phrases like “I have a gut feeling” have been in our language for many years, yet the knowledge that the vagus nerve connects the two is relatively new. Your gut feelings actually have basis in biology. The vagus nerve acts as a sort of message translator between your gut and your brain, using electrical impulses to communicate between the two.
The vast majority of these messages go from the gut (via the ENS, or enteric nervous system in the digestive tract) to your brain; so in essence, your belly really does tell your brain how you’re feeling.
5. Prevents Inflammation
There’s no question that inflammation plays a role in bone health as well as many other health conditions, and in particular, heart disease. Inflammation literally ages your bones via oxidative damage, making them more vulnerable to fracture.
The vagus nerve is always on a reconnaissance mission, gathering information from the organs as to the presence of inflammatory substances like cytokines. It then alerts the brain, which in turn responds by sending out anti-inflammatory neurotransmitters. This underscores the fact that inflammation is meant to be temporary; once it’s done its job, such as promoting the healing necessary for an injury, it needs to be “shut off.” The vagus nerve performs this vital action.
6. Keeps You Breathing
By causing the secretion of the neurotransmitter acetylcholine, the vagus nerve tells your lungs to breathe, over and over. Breathing is important for obvious reasons, but deep breathing is even more so. When you breathe deeply, it not only alkalizes your body, but it also stimulates the vagus nerve itself, producing a sense of calm and reducing bone-damaging stress. So it helps your bones two ways, and also reduces depression and anxiety (more on this later).
7. Helps You To Relax
Did you know that your body has a mechanism in place for relaxation? It makes sense – something must kick in to cause you to calm down from an intense, stressful moment. Acetylcholine is involved once again, as well as the vagus nerve’s stimulation of this neurotransmitter. Acetylcholine signals the vagus nerve to release relaxing, feel-good hormones such as prolactin and oxytocin – to name a few – to the organs where they are needed.
The many branches of the vagus nerve distribute these relaxation chemicals directly to the organs that need them, causing you to feel calmer.
Strengthening this vagus response helps you to recover more quickly from stress, which is where the Valsalva maneuver comes in.
What Is The Valsalva Maneuver And How It’s Done
Antonio Valsalva (1666-1723) was an Italian anatomist who spent much of his scientific career studying the ear. He is responsible for the term Eustachian tube, and he also developed the maneuver we’re going to look at today. The original intention of the Valsalva maneuver was to clear debris and infection from inside the ear, but its uses and benefits extend far beyond this to include vagus nerve stimulation. Here’s how it works.
The Valsalva maneuver increases pressure within the chest cavity and expands your abdomen, setting a series of physiological processes into place. As mentioned earlier, the vagus nerve is directly connected to your heart’s rhythm, which is why doctors recommend the Valsalva maneuver to halt an SVT episode. (SVT is supraventricular tachycardia.) Because of this, if you have any heart condition, make sure you ask your doctor before performing this maneuver.
Here’s how to do it:
- Hold your nose so you can’t breathe through it.
- Close your mouth and try to breathe out through your pinched nose.
- Hold this “forced exhalation” for 10 to 15 seconds, and then release.
Breathing against a closed-off airway increases chest cavity pressure, thus forcing the heart to pump more blood for a few seconds. Then the opposite happens – the pressure now has the effect of preventing blood from returning to the heart, so blood vessels constrict, raising blood pressure.
When you resume normal breathing, the pressure drops suddenly, allowing the chest cavity to expand and blood to fill the heart again. Ironically, cardiac output may actually drop even more at this point. Seconds later, your heart and lungs resume normal rhythm and breathing.
This maneuver “tones” the vagus nerve, which can also be accomplished by deep breathing. This is best performed by drawing a slow, deep breath in through your nose, envisioning your abdomen filling with a balloon. Let your ribs expand all around and your belly as well. Breathe in for about seven seconds, hold it for a moment, and then slowly exhale through your nose for 11 seconds. Repeat six to 12 times.
Anxiety And Depression Relief
Remember that the vagus nerve controls the “calm down” aspect of the parasympathetic nervous system? Stimulating it, then, kicks this calm-down response into gear, reducing stress, anxiety, depression, and the cortisol that accompany these conditions. In addition to alkalizing your pH, this is another way that deep breathing is excellent for your bone health.
The bottom line is, stress is acidifying. The Save Our Bones Program did not overlook this fact, and you’ll find an entire chapter (Chapter 14) devoted to the issue of relaxation and stress reduction. As you learn how to relax your mind and body, it helps you to control your stress and cortisol levels.
Chapter 14 includes 10 easy behavioral changes you can make that will have a huge impact on your sense of well-being and your bone health, as well as specific relaxation techniques you can employ every day to bring a sense of calm.
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The Save Our Bones Program certainly covers all the bases when it comes to bone health!
Till next time,
1 Chen, C. C. and Williams, C.L. “Interactions between epinephrine, ascending vagal fibers, and central noradrenergic systems in modulating memory for emotionally arousing events.” Front Behav Neurosci. 6. 35. (2012). Web. November 1, 2016. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3384987/