The Vagueness of the Vagus Nerve Demystified

From Deepak Chopra to that random TikTok fitness influencer, the vagus nerve fever has not spared anyone. Just as of today, the hashtag ‘#vagusnerve’ has been used a whopping n number of times on the internet, with about 120K+ posts on Instagram alone. For many of us, the vagus nerve has become a thing of fascination in recent times, and every dimension of the fitness & health industry is capitalizing on this newfound excitement. 

While online marketplaces are brooding with electrical stimulators, crystals and natural supplements that claim to activate or stimulate your vagus nerve, social media, and blogs are teeming with simple hacks you can practise at home – such as plunging your face into cold water, coffee enemas, navel oiling, and breathing techniques to stimulate your vagus nerve. While some of these products and techniques work, many are mere gimmicks capitalizing on social trends. In this article, we will delve deep into the mysteries of the vagus nerve, why it has become a thing of excitement in recent times, and how you can maintain and improve your vagal nerve health.

What is the Vagus Nerve?

The vagus nerve is the longest nerve of the autonomic nervous system of the body and serves as a 2-way communication channel between the brain and several critical organs like the heart, lungs, and abdominal organs – specifically the gut, and plays an important role in involuntary physiological processes such as breathing, digestion, control of mood, heart rate, and immune responses. Although referred to in the singular, the vagus is actually a pair of 2 nerves – the left and right vagus nerves – that run from the brain stem down through each side of the neck and into the torso, branching outward into the internal organs. Although the vagus nerve comprises both sensory and motor fibres, it is predominantly sensory in nature as it conveys a vast amount of sensory information to the brain stem. [1]

Primary functions of the Vagus Nerve:

The primary functions of the vagus nerve are as follows - 

1. Parasympathetic Nervous System Control - helps regulate and balance many bodily functions, such as heart rate, respiratory rate, and digestion; promotes rest and relaxation
2. Heart rate regulation - helps control heart rate by transmitting signals from the brain to the heart's sinoatrial (SA) node. A healthy vagus nerve helps in maintaining a healthy heart rhythm.
3. Respiratory control – Regulates the rate and depth of breathing
4. Digestive function - Stimulates the production of stomach acid, facilitates peristalsis (the wave-like contractions of the digestive tract), and promotes the release of digestive enzymes.
5. Gastrointestinal reflexes – Plays a key role in triggering gastrointestinal reflexes, including the gag reflex, which protects the airway by triggering a reflexive cough or gag when foreign objects are detected in the throat.
6. Taste and sensation – Carries sensory information from the throat, esophagus, and parts of the digestive system to the brain related to taste sensations, hunger, and fullness. 
7. Inflammatory response regulation – Helps regulate any persisting inflammation in the body by dampening the body’s inflammatory response.
8. Communication with other organs to maintain homeostasis – Communicates with various organs and tissues throughout the body, helping to maintain homeostasis and coordinate responses to changes in the external and internal environment
9. Emotional regulation – Regulates body's stress response and may influence emotional well-being
10. Immune system modulation – Modulates the body’s immune response by detecting the presence of inflammatory mediators. [2]

How does vagus nerve stimulation help the body?

The vagus nerve is 80% sensory in nature - meaning it collects information and signals from different internal organs of your body and communicates to your brain. The brain in turn responds by regulating the automatic processes of the body such as digestion, sleep, breathing, inflammation, etc. The parasympathetic nervous system, which is the ‘rest and digest’ system calms the body during times of stress, and the vagus nerve is a key player in the parasympathetic system. When you are relaxed, sleeping, or in a restorative phase, the vagus nerve is dominating – higher activity levels of the vagus nerve lead to a more positive impact on homeostasis. 

When you stimulate your vagus nerve, the ‘tone’ of your vagus nerve improves. Vagal tone is an internal biological process that represents the activity of the vagus nerve. Increasing your vagal tone activates the parasympathetic nervous system, and having a higher vagal tone means that your body can relax faster and a higher degree of sensory activity via the vagus nerve. 

Over the years, researchers have observed several outcomes of stimulating the vagus nerve. Vagus nerve stimulation (VNS) activates parts of the prefrontal cortex which in turn regulates the limbic regions of the brain that control emotions, ultimately resulting in a calmer, relaxed state of mind. This can help reduce symptoms of depression and bipolar disorder. VNS activates anti-inflammatory pathways in the body thus helping combat inflammatory conditions like Crohn's, rheumatoid arthritis, etc. VNS helps improve glucose homeostasis by altering key metabolic functions and can help in the treatment of diabetes. While our understanding of the vagus nerve and its extensive functions are only at the tip of the iceberg as of today, there is a plethora of research being undertaken to evolve our knowledge of the vagus nerve. [3]

How to improve vagal nerve tone?

Broadly speaking, there are 2 ways to improve your vagal nerve tone. The first method is a medical procedure restricted to individuals who have epilepsy, stroke, or treatment-resistant depression. It involves implanting a device that sends regular, mild pulses of electrical energy to your brainstem through the vagus nerve. After reaching your brainstem, the electrical charge is discharged to different areas of your brain to change the way brain cells work. The procedure lasts about 45-90 minutes with the patient under general anesthesia and is performed by a neurosurgeon. While the procedure is generally considered safe, it does come along with its share of side effects that are usually temporary in nature. The most common temporary side effects include hoarseness, coughing, and shortness of breath. The implantation surgery may result in pain, infection, breathing difficulties, and damage to surrounding nerves. While these patient risks are extremely subjective, one needs to be thoroughly evaluated to understand any potential risks they may face, and have extensive discussions with the doctor to get a full understanding of the procedure before they sign up for it. [4]

The other way to improve your vagal nerve tone is to incorporate some healthy lifestyle changes that focus on the stimulation of the vagus nerve. As mentioned earlier in the article, there are plenty of hacks listed on the internet that can stimulate the vagus nerve. Listed here are some of the proven methods that can help stimulate your vagus nerve.

1. Breathing exercises: Deep breathing exercises, specifically diaphragmatic breathing exercises can help stimulate your vagus nerve by improving the vagal nerve tone. During deep breathing exercises, your respiration rate reduces leading to a smaller inhalation-exhalation ratio. A slowed-down respiration rate can increase vagal nerve activity through neurons that barter communication between the respiratory system and the central nervous system. Effectively, deep breathing also results in lowered heart rate and blood pressure, inhibits the sympathetic nervous system resulting in a reduction of stress and indirectly the hypothalamic pituitary adrenal axis, and activates an anti-inflammatory pathway. [5], [6]
2. Exercise: Research shows us that those who exercise – specifically endurance exercises have a higher vagal nerve activity as compared to those who do not. Endurance training includes activities that target your breathing and heart rate such as walking, jogging, swimming, biking, etc. Endurance exercises when performed in moderate intensity intervals help reduce the activity of the sympathetic nervous system and improve the autonomic nervous system, specifically the vagus nerve. [7]
3. Nutrition: Poor eating habits have been shown to impair the vagal nerve tone. The vagus nerve as we know connects the brain to the gut and regulates digestion and gastrointestinal motility. The gut produces neurotransmitters and are sent along the vagus nerve to the brain and manages changes in mood, energy levels, memory, etc. While there isn’t enough research to substantiate whether poor gut health results in low vagal tone or vice versa, it is often noted that vagal nerve health and gut health go hand-in-hand with each other. Taking a holistic approach, it is therefore important to eat healthy, nourishing and nutritious food to boost your gut health. Talking to a good functional practitioner can help you understand what foods work best for your gut. [8], [9]

References:

1. Bonaz, B., Sinniger, V., & Pellissier, S. (2017). The Vagus Nerve in the Neuro-Immune Axis: Implications in the Pathology of the Gastrointestinal Tract. Frontiers in immunology, 8, 1452. https://doi.org/10.3389/fimmu.2017.01452
2. Breit, S., Kupferberg, A., Rogler, G., & Hasler, G. (2018). Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders. Frontiers in psychiatry, 9, 44. https://doi.org/10.3389/fpsyt.2018.00044
3. Breit, S., Kupferberg, A., Rogler, G., & Hasler, G. (2018). Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders. Frontiers in psychiatry, 9, 44. https://doi.org/10.3389/fpsyt.2018.00044
4. Mandalaneni K, Rayi A. Vagus Nerve Stimulator. [Updated 2023 Aug 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK562175/
5. Magnon, V., Dutheil, F., & Vallet, G. T. (2021). Benefits from one session of deep and slow breathing on vagal tone and anxiety in young and older adults. Scientific reports, 11(1), 19267. https://doi.org/10.1038/s41598-021-98736-9
6. Gerritsen, R. J. S., & Band, G. P. H. (2018). Breath of Life: The Respiratory Vagal Stimulation Model of Contemplative Activity. Frontiers in human neuroscience, 12, 397. https://doi.org/10.3389/fnhum.2018.00397
7. Kai, S., Nagino, K., Ito, T., Oi, R., Nishimura, K., Morita, S., & Yaoi, R. (2016). Effectiveness of Moderate Intensity Interval Training as an Index of Autonomic Nervous Activity. Rehabilitation research and practice, 2016, 6209671. https://doi.org/10.1155/2016/6209671
8. Young, H. A., & Benton, D. (2018). Heart-rate variability: a biomarker to study the influence of nutrition on physiological and psychological health?. Behavioural pharmacology, 29(2 and 3-Spec Issue), 140–151. https://doi.org/10.1097/FBP.0000000000000383
9. Arneth B. M. (2018). Gut-brain axis biochemical signalling from the gastrointestinal tract to the central nervous system: gut dysbiosis and altered brain function. Postgraduate medical journal, 94(1114), 446–452. https://doi.org/10.1136/postgradmedj-2017-135424

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