Introduction to the Vagus Nerve
What we call the vagus nerve is actually a pair of nerves, one on each side of the body. The human body has 12 cranial nerve pairs, and the vagus nerve is the 10th one. The cranial nerves emerge directly from the brain or brain stem and relay messages and information between the brain and various parts of the body. (1, 2)
The vagus nerve is the only cranial nerve pair of the 12 that originates in the cranium, the part of the skull that encloses the brain. Although this versatile nerve has some critical functions in and around the face and throat, it mainly connects the head to other areas of the body. In fact, it is the only nerve pair to do so. The word vagus comes from a Latin word meaning “wandering.” This aptly named nerve wanders throughout the body to many vital organs, delivers signals from the brain, and returns messages from the organs. These organs include the: (3, 4)
- Colon
- Digestive tract
- Gallbladder
- Heart
- Kidneys
- Liver
- Lungs
- Neck (esophagus, larynx, pharynx)
- Sex organs (females)
- Spleen
- Stomach
- Tongue
- Ureter
The brain has to pass specific pieces of information to all of these organs, and they all — especially the ones in the gut — send information back to the brain. The vagus nerve is essential for this bidirectional communication. (5)
The brain uses the vagus nerve to control the parasympathetic nervous system, which covers the detox, digest, healing, recovery, and rest aspects of the nervous system. Although the vagus nerve is not the only nerve that controls the body’s ability to decrease stressors, it is by far the most important due to its far-reaching effects. No other nerve has such a widespread impact. (6)
A Deeper Look: The Vagus Nerve, the Mitochondria, and the Cell Danger Response
Well-known for their function as powerhouses of the cells, mitochondria are organelles that produce ATP, the body’s energy currency. But it’s less known that mitochondria also have a substantial role in cellular defense. When under threat, the mitochondria shift from being power plants to defenders. Mitochondria protect and defend themselves and the body when they face threats from chemicals, environmental stressors, heavy metals, infections, physical trauma, psychological trauma, and toxins. They do this through a metabolic function known as the cell danger response (CDR) process. Theories associated with CDR offer a new paradigm for understanding disease. (1, 7, 8)
Metabolic dysfunction drives chronic disease
CDR is a natural, healthy way for the body to heal itself after threat or injury. As the mitochondria respond to a threat and shift from their normal energy production into the specialized CDR operation, they fight off whatever threatens the body. Therefore, CDR protects the cells and the body from harm.
But if the body remains in CDR mode too long, it can create a barrier to healing, because the mitochondria have shut down energy production to deal with the threat. In some cases, the body doesn’t shift back out of CDR as it should. (9)
Fatigue becomes a significant issue when the body gets stuck in CDR. While in cellular defense mode, the mitochondria produce less ATP to fuel the body. With a chronic infection, people typically shift to a persistent state of CDR with low energy production.
In this situation, it’s important to find what is blocking the body from healing, not what first caused the illness. The bacteria, chemical, toxin, or virus may be long gone, but the CDR process continues, and that’s when an illness becomes chronic. Unblocking the healing process can help fight chronic illness. This is where the vagus nerve comes in. (1)
Stimulating the vagus nerve to switch off the CDR
Stimulating both the dorsal and ventral branches of the vagus nerve may help to switch off CDR.
Bodies under threat from infection or trauma don’t stay in a fight-or-flight response all the time. Many of them are in a freeze response, which is a collapsed, hibernation mode that comes from the dorsal part of the vagus nerve. This hibernation mode is similar to what happens when an animal plays dead when threatened. (1)
In other words, the body’s response to threats is three-fold:
- Fight-or-flight mode (the sympathetic nervous system response)
- Rest, digest, and heal mode (the parasympathetic response of the ventral vagus nerve)
- Collapsed, hibernating, playing-dead, or shut-down mode (the parasympathetic response of the dorsal vagus nerve)
Therefore, the trick is to get the nervous system to shift to the rest, digest, and heal mode by stimulating the ventral vagus nerve. This will help fight chronic illness, reduce inflammation, and stimulate more healing functions.
When the ventral part of the vagus nerve is in full swing, you feel good. You feel happy and uplifted. You feel socially connected. You are in a state of well-being. And this mirrors the cellular level, because the vagus nerve provides communication between the brain and the cells. (1)
The ventral vagus nerve plays a fundamental role in healing, and it’s also the part that gets switched off when CDR takes over. When the ventral vagus nerve is stimulated, it signals to the body that everything is okay. That way, the body can begin to move away from being stuck in CDR and allow for healing. Because everything is connected, what happens at the cellular level also happens at the nervous-system level.
Determining If the Vagus Nerve Is Working Correctly
Because of the vagus nerve’s widespread impact, it’s important to know whether it’s functioning correctly. A properly working vagus nerve has clear pathways with free-flowing information in both directions. But specific situations, such as direct injuries or diseases, can cause interference and then lower vagal function. There are two simple tests to see if the vagus nerve is functioning properly: (10)
- Bowel transit time is a measurement of how long it takes for food to travel through the digestive tract. The vagus nerve keeps the digestive tract moving at an optimal pace. Variations from this optimal pace can signal a loss of vagus nerve control.
- Heart rate variability (HRV) measures the variation in time between each heartbeat.
Vagal tone and HRV
The autonomic nervous system is subdivided into two components:
- Sympathetic: Fight-or-flight response
- Parasympathetic: Relaxation response
The autonomic nervous system sends a signal to the heart via the vagus nerve. That signal continues to the sinoatrial (SA) node of the heart, which regulates that organ’s electrical activity. Communication between the vagus nerve and SA node is very clear when the following occur:
- The vagal nerve tone is healthy.
- The autonomic nervous system functions well.
- There is unimpaired balance between the sympathetic and parasympathetic nervous systems.
In this case, there will be small variations in the amount of time between each beat of the heart. That is what high heart-rate variability is. (4, 11)
HRV shows vagal nerve tone by measuring variations in the time between each heartbeat. Measuring HRV is a noninvasive way to identify imbalances in the autonomic nervous system and vagus nerve. If an individual’s system spends more time in fight-or-flight (sympathetic) mode, the variation between subsequent heartbeats is low. When CDR is activated, both vagal tone and HRV decrease. (2, 4)
Recent research shows a relationship between low HRV and worsening anxiety or depression. A low HRV is also associated with an increased risk of cardiovascular disease and death. (2)
Supporting the Mitochondria to Support the Vagus Nerve
Because this system is bidirectional, supporting the mitochondria can also support the vagus nerve and vagal tone. Poor vagus nerve function may manifest in many ways, including: (3, 5, 12, 13, 14, 15)
- Anxiety
- B12 deficiency
- Chronic fatigue
- Chronic inflammation
- Depression
- Difficulty swallowing
- Dizziness and fainting
- Gastroparesis (delayed gastric emptying)
- Heartburn
- High or low heart rate
- Irritable bowel syndrome
- Weight gain and obesity
Not surprisingly, most of these signs and symptoms of vagus nerve dysfunction indicate poor mitochondrial function as well. That means that removing any upstream sources of interference that damage the mitochondria — such as chemical toxins, environmental toxins, EMFs, heavy metals, and forms of infection (bacterial, parasitic, and viral) — may help support the mitochondria and help the body heal. (16)
Activating the Vagus Nerve and Reversing the CDR
To combat chronic illness and other issues, the aim is to shut off the fight-or-flight response and exit the dorsal vagus hibernation mode. Then you can reestablish the ventral vagus nerve’s rest, relax, and heal process. Stimulating the vagus nerve helps switch off CDR so that the mitochondria return to energy-producing mode again. Anything that raises HRV increases vagal tone.
Daily vagus nerve stimulation can come from lifestyle modifications such as: (17)
Acupuncture
Acupuncture may help stimulate the vagus nerve and improve HRV. Research has shown that stimulating the vagus nerve with acupuncture not only helps vagal tone, but can also produce dopamine and help reduce inflammation. In addition, in a study, performing acupuncture on the auricular branch of the vagus nerve caused participants’ heart rate to decrease and their HRV to increase. For these reasons, acupuncture can be a helpful treatment for many different health conditions, as is already widely believed. (18, 19, 20)
Chewing
Chewing, including both chewing food thoroughly when eating and chewing gum, also activates the vagus nerve. Taking the time to chew food before swallowing it will set the correct digestion sequence in motion and allow the vagus nerve to function as it should. (21)
Coffee enemas
Enemas trigger the vagus nerve by expanding the bowel. Coffee enemas in particular offer a unique form of cleansing for the liver and bile duct drainage systems. In your body’s detox process, toxins are dumped into the bile, and the toxic bile gets released into the intestines for evacuation. The body’s entire blood supply normally circulates through the liver every three minutes. Holding a coffee enema for a time will supercharge this cleansing, and the water content of the coffee helps to rinse out the toxic bile. (22)
Cold therapy
Cold therapy and cryotherapy have many benefits, including decreased inflammation, enhanced immune function, and faster recovery from exercise. Acute cold exposure activates the vagus nerve and the neurons through vagus nerve pathways. That means that cold exposure can also increase parasympathetic activity via the vagus nerve, lowering the fight-or-flight sympathetic response. (23)
Acute cold exposures that can stimulate the vagus nerve include:
- Cold showers
- Cryohelmets or cold vests
- Dipping the face in cold water
- Drinking cold fluids
- Splashing cold water on the face
Deep breathing
It’s widely accepted that deep, slow breathing can promote relaxation. Vagal stimulation can lead to relaxation, but the reverse is also true — relaxation can stimulate the vagus nerve. Therefore, inducing a relaxed state through deep breathing can help increase vagal tone. The technique involves breathing slowly as the belly rises and falls to engage the diaphragm muscle. The more the belly expands upon inhale and contracts upon exhale, the deeper the breathing. (6)
Gargling
Gargling is another way to stimulate the vagus nerve and is an easy exercise to fit into a daily routine. Gargling with a glass of water each morning and night will help to work the muscles in the back of the throat. This activates the vagus nerve and boosts digestive function. Tell your patients to keep a glass next to their bathroom sink as a daily reminder to perform this exercise. Gargling to the point where tears well up in the eyes is even more useful. (24, 25)
Intermittent fasting
Intermittent fasting can provide many health benefits. It may boost metabolism, improve mitochondrial and cognitive function, and reduce the risk of diseases. The reason for this may stem from the fact that intermittent fasting can stimulate the vagus nerve and improve vagal tone. It also helps to increase high-frequency HRV. (26)
Laughter
Laughter is known to provide a range of health benefits. It increases endorphins and blood flow while decreasing pain and stress hormones, thus encouraging overall well-being. Most importantly, laughter also increases the production of oxytocin, which is thought to help with everything from boosting immunity to fighting depression to lessening schizophrenia-related cognitive problems. Oxytocin may also improve gut health, which ties in directly with the vagus nerve. When we have healthy microbes in our gut, they send out signals via the vagus nerve that stimulate the production of more oxytocin. (27)
In a study of laughter among yoga participants, laughter seemed to improve their mood, help with their long-term anxiety, and increase their HRV. (28, 29)
Massage
Massage can be beneficial in activating the vagus nerve. Foot reflexology and massages can increase HRV and vagus nerve activity and lower blood pressure and heart rate. (30)
Research also suggests that stimulating the vagus nerve through massage and reflexology can be a successful pain treatment. This effect occurs when the massage and reflexology techniques alter the perception of pain, block pain signals, help regulate emotions, and increase the production of endorphins or neurochemicals. Massage may also help reduce pain by activating sensory nerves and releasing oxytocin. The primary way that that happens is by stimulating the vagus nerve, which affects receptors under the skin and regulates the autonomic nervous system. (31)
Meditation
Two different types of meditation — loving-kindness meditation and guided mindfulness meditation — have been shown to increase HRV and vagal tone. Chanting during meditaton stimulates the vagus nerve as well. Regular meditation and positive affirmation can help people achieve better HRV. (6, 32)
Physical activity
Along with its other numerous benefits, physical activity seems to help stimulate the vagus nerve. One recent study found that mild exercise activated the vagal nerve, which then supported gastric emptying and improved digestion. (33, 34, 35)
Singing and vocal exercises
The vagus nerve attaches to the vocal cords, so singing, humming, and other vocal exercises can activate it. Energetic singing, hymn-singing, and mantra-chanting all increase HRV in slightly different ways. Loud singing gives the muscles at the back of the throat a workout, activating the vagus nerve. (36, 37)
Social enjoyment
Being social with friends and family is an excellent way to relax. Positive social interactions lead to positive emotions, which help improve vagal tone. Studies have shown a connection between the social engagement system and vagal tone with how people experience social connectedness and positive emotions. People who have higher baseline vagal tone tend to have greater levels of positive emotions, and the opposite effect also occurs: Positive emotions and social engagement influence cardiac vagal tone. (38, 39)
Yoga, tai chi, and qigong
Yoga is one exercise that activates the parasympathetic nervous system. It improves blood flow, digestion, lung capacity, and mood and anxiety levels. GABA — a neurotransmitter associated with lifting mood and anxiety — increases in people who perform yoga and other mindful movement exercises. Similarly, studies show that tai chi increases HRV in patients who have coronary artery disease, while qigong can improve HRV in survivors of nasopharyngeal cancer. (6, 40, 41, 42)
Other methods
Some other ways to stimulate the vagus nerve include: (43, 44)
- Circadian rhythm management
- Eating healthy foods
- Gratitude journaling
- Improving sleep quality
- Spending time in nature
- Sunlight exposure
- Using essential oils
- Water therapies
Many of these are practical and don’t cost much, yet they help to reset the nervous system.
Recovery from Vagus Nerve Dysfunction and Chronic Illness
A calm, relaxed emotional state helps encourage recovery. This causes the vagus nerve to signal to the brain and individual cells to initiate healing. This message acknowledges that it’s safe for the body to switch to healing mode. The vagus nerve manages digestion, rest, and recovery. Following some of these exercises and lifestyle habits may help your patients or clients feel better, as well as providing a whole new relaxed, calm, and comfortable life experience.
