Optimal functioning of Vagus nerve is critical for overall health
Vagus nerve regulates health by regulating many of the body functions by facilitating synthesis, release or action of various hormones in the body.
Vagus nerve, the longest and most complex of the cranial nerves, runs from the brain through the face and thorax to the abdomen. Vagus nerve is also called The X cranial nerve or 10th cranial nerve.
But why is Vagus “Buddha” nerve important for your health?
Vagus Nerve, the interface of parasympathetic nervous system, helps control the functioning of brain, neck, ears, tongue, lungs, heart, stomach, intestines, liver, kidneys and female reproductive organs. It is also involved in speech, eye contact, taste and facial expressions.
When Vagus nerve is activated, blood pressure stabilises, immune system functions at optimised levels, respiratory rate corrects itself, antibody titers improve significantly, sleep pattern and mood improves, digestive system and natural killer cells (NK lymphocyte cells) function increases and above all, YOUR overall health becomes better.
1. Vagus nerve prevents inflammation
A certain amount of inflammation is normal after an injury or infection, but, some people experience on overabundance of inflammatory processes which can trigger multitude of health issues including autoimmune diseases, sepsis, heart attack, stroke, insulin resistance, tumor growth and organ damage.
It is reported that acetylcholine, the principal neurotransmitter of Vagus nerve inhibits tumor necrosis factor (TNF) and interleukins – key players in most inflammation and cell disorders.
2. Vagus nerve helps you Breathe
The neurotransmitter acetylcholine, released by vagus nerve helps in communication between Brain and Diaphragm. Vagus Nerve gives you the breath for life by stimulating your lungs to breathe. Absence of acetylcholine will stop the Breath in no time.
3. Vagus nerve conveys messages between your Gut and Brain
About 80-85% of nerve fibers in Vagus nerve transfer visceral feelings or gut instincts from gut (enteric nervous system) to the brain and also from brain to the gut, making a feedback loop.
A 2014 Swiss study in Journal of Neuroscience, identified how the emotional intuitions or gut instincts coming up to brain through Vagus nerve are associated with different responses to fear. In the test animals, researchers severed nerve fibers carrying information from gut to brain, but kept the fibers sending information from brain to gut, intact.
The research revealed that the test rats were not that afraid to begin with i.e. having low level of innate fear, but when they became afraid, they had hard time overcoming this fear i.e. they retained learned fear for longer time.
Research also concluded that optimal vagal tone of vagus nerve helps to come back from stressful situations easily.
In fact, vagal nerve stimulation, an accepted treatment in the alternate medicine, is fast becoming the recommended allopathic treatment for epilepsy, severe depression, post-traumatic stress disorders and other anxiety disorders.
4. Vagus Nerve maintains Digestive Health
Vagus Nerve helps in food intake, digestion, satiety, maintaining gastrointestinal barrier and perform immune-modulatory functions in the gut. It increases production of gastric acid and digestive juices and maintains gut motility. It also helps stimulates production of gastric intrinsic factor; a glycoprotein that helps in absorption of vitamin B12.
5. Vagus Nerve promotes general Kidney and Bladder function
Vagal stimulation increases blood flow to kidneys and helps in better filtration of blood. Vagus nerve helps to excrete sodium via urine by releasing dopamine in kidneys and thereby lowering blood pressure.
6. Vagus nerve regulates the strength of Memories
Researchers at university of Virginia reported that vagal nerve stimulation releases norepinephrine (a neurotransmitter) into amygdala (part of brain that regulate arousal, memory and feelings associated with emotional stimuli) and activates it.
Upon activation, amygdala slots the emotionally activating experiences into long-term memory.
Understanding the pathways of emotional memory can aid clinical treatment of intrusive memories and opens promising treatment for conditions like Alzheimer’s.
7. Vagus nerve controls Heart rate and Blood pressure
Vagus nerve acts on heart’s pacemaker by releasing acetylcholine, which slows the pulse and blood pressure.
Many studies have reported the benefits of vagus nerve stimulation in patients with heart failure. In heart failure, the balance between sympathetic and parasympathetic nervous system is erratically altered and it leads to sympathetic over-activity.
A 2011 study in European Heart Journal reported that repeated vagus stimulation could improve quality of life and the heart’s efficiency to pump blood in patients with heart failure. Another study published in journal of cardiac failure in 2014 echoed the similar results. After 6 months of vagus stimulation, patients’ heart pumped 4.5% more blood per beat than before.
Multiple studies are underway investigating the effects of vagus nerve stimulation in atrial fibrillation (where heart flutters abnormally) and tachycardia (abnormally increased heart rate) as well.
8. Vagus nerve stimulation can lower and control blood sugar concentrations
A 2015 study in PLOS ONE, showed that vagus nerve stimulation have an anti-diabetic effect in animal models. Researchers explained that transcutaneous (through skin) stimulation of vagus nerve triggers release of melatonin hormone in blood.
It is discovered recently that melatonin plays a protective role against type2 diabetes by regulating glucose metabolism via controlling insulin secretion and leptin production. Also, melatonin has shown to influence food intake and body weight- risk factors for diabetes type 2.
9. Vagus Nerve helps in mood upliftment
Vagus nerve stimulation can be an effective treatment of chronic depression that has failed to respond to drugs. Studies suggest that, electrical stimulation of vagus nerve increases level of norepinephrine, which communicates between nerve cells in parts of brain implicated in mood disorders. In fact, some antidepressants also work by increasing level of norepinephrine in brain.
In 2005 U.S. Food and Drug Administration has approved electrical stimulation of vagus nerve as a therapy for drug-resistant depressive patients.
10. Vagus nerve stimulation can prevent and treat chronic cluster headaches
Cluster headache is a debilitating pain usually limited to one side of face, which tends to recur over a period of several weeks.
The positive effect of Vagus Nerve stimulation, for headache cure, was first found when a company called Electrocore was experimenting their device on asthmatic patients (by relying on anti-inflammatory action of nerve). Along with Asthma, the device also helped people cure their cluster headaches.
A 2016 study published in the journal Cephalgia, reported that people suffering from an average of 67.3 cluster headaches in a month experienced around 3.9 fewer attacks/ weeks on an average after using transcutaneous electrical vagal stimulator along with standard treatments.
11. Vagus nerve initiates body’s relaxation response
Vagus nerve, when stimulated, releases proteins like prolactin, oxytocin and vasopressin, which help you to calm down. People with stronger vagal tone are more likely to recover quickly from stress, injury or illness.
12. Vagus nerve stimulation can be effective in treatment-resistant epilepsy
As reported by researchers in Journal Clinical Neurology and Neurosurgery 2015, average seizure reduced by 32% just after 6-9 months of vagal stimulation. Patients reported only mild side effects, which get subsided when stimulation was stopped.
13. Vagus nerve stimulation helps to regulate one’s own emotions
Studies have shown that high vagal tone is associated with positive emotions and vice versa, which means that changes in habitual emotions can very strongly influence vagal tone.
Positive emotions can in turn promote positive social bonding, which can influence physical health. Many studies have proved the fact that emotional health can influence physical health.
14. Vagus nerve normalises the elevated hypothalamic-pitutary-adrenal (HPA) axis
HPA axis is comprised of hypothalamus (Brain), pituitary (Brain) and adrenal glands (present near kidneys) and is known as body’s central stress response system and regulates body processes like digestion, immune system, mood and emotions, libido and energy storage and expenditure.
During stress (emotional, physical, injury or illness) hypothalamus stimulates pituitary gland by releasing a hormone called corticotropin releasing hormone (CRH).
Upon stimulation, pituitary gland releases another hormone called adrenocorticotrophic hormone (ACTH), which is transported in circulation to adrenal glands present near kidneys.
Adrenal glands rapidly synthesize cortisol, epinephrine and norepinephrine (stress hormones) in response to pituitary stimulation.
These hormones initiates fight or flight response in the body.
Activation of HPA axis can induce physical changes in the body, including increased respiratory and heart rate, pain, elevated level of inflammatory mediators and suppression of immune system.
These changes are detected by Vagus nerve, which once stimulated, can inhibit HPA axis by bringing about neuroendocrine homeostasis in the body.
15. Vagus nerve boosts testosterone production
Low levels of testosterone can lead to moodiness, weight gain, loss of muscle mass and diminished libido.
What suppresses testosterone levels? Elevated level of stress hormone Cortisol affects the release of testosterone from testicles. Generally an enzyme called 11ßHSD-1, produced within the testicles, can protect testosterone from acute effects of stress.
But, this enzyme cannot neutralize elevated level of cortisol and due to this, freshly produced testosterone hormone gets damaged even before they are released from the testicles.
Vagus nerve stimulation helps check the elevated cortisol in the blood; boosts testosterone production to the required levels.
16. Estrogen dependent antinociceptive mechanism is mediated by Vagus nerve
It is reported that estrogen modulates visceral (body organs) pain. A study published in journal of pain 2014, described the exact mechanism how estrogen processes antinociceptive (reduction of visceral pain) effects and reported that the mechanism of pain reduction is carried by vagus nerve.
17. Vagus nerve regulates Growth Hormone (GH) secretion
What happens in suppressed Growth Hormone (GH)? Growth hormone (GH), also known as Somatotropin stimulates growth, cell reproduction, and cell regeneration and any imbalance can trigger reduced sex hormone-binding globulin (SHBG), reduced energy, muscle mass, strength, osteoporosis, impaired concentration, memory loss, baldness and cardiac dysfunction are some of the health concerns associated with Growth Hormone deficiency, in adults.
The growth hormone is secreted from pituitary gland in brain. Its secretion is dependent on hormones secreted by hypothalamus. Recently it is reported that grehlin, the hunger hormone secreted by gastrointestinal tract also induces growth hormone secretion.
The vagus nerve is crucial in the regulation of Growth Hormone (GH) secretion from pituitary gland and it also mediates ghrelin “hunger hormone” dependent growth hormone secretion (regulatory peptides 2011).
18. Vagus nerve controls hormonal regulation of appetite
Hormones, nutrients and neural influence control regulation of feeding behavior.
Hormones like Cholecystokinin (CCK) controls short-term inhibition of food intake and leptin controls long-term feeding behavior and body weight.
Both CCK and leptin generate satiety signal via vagus nerve. It is conceivable that malfunction of vagus nerve may result in eating disorders (Journal of Neurogastroenterology and Motility 2011).
19. Vagus nerve controls the Glucose lowering effect of insulin; glucose homeostasis
Insulin activates K-ATP channels in arcuate nucleus in the hypothalamus and modulates food intake, energy balance and glucose homeostasis.
Vagus nerve decreases release of agouti-related protein (AgRP), a potent appetite stimulator. Insulin signaling via Vagus nerve reduces glucose production from liver by decreasing enzymes required to produce glucose.
20. Vagus nerve stimulation releases vasoactive intestinal peptide (VIP)
Vagus nerve stimulation increases level of VIP, which stimulates heart contractility. It also causes dilation of blood vessels in heart, lowers blood pressure, and relaxes muscles of stomach and gall bladder.
All these researches seem to be very promising. But in human body nothing works in isolation. Knowing the vagal nerve’s widespread innervations, we are not very sure how electrical stimulation of nerve affects other functions. So caution is warranted when it comes to invasive procedures and surgical implants. But the question arises can we raise vagal tone without getting implants? The answer is yes! Besides Yoga asana, pranayama and meditation there are a few other ways one can raise vagal tone, they are mentioned in the next article…