The immune system is a complex organ network. It relies heavily on adequately functioning bodily processes to perform its duties. When the immune system has what it needs, it keeps you protected from foreign pathogens and chronic diseases. However, the immune system can go haywire when things aren't running smoothly, leaving you susceptible to various illnesses, health disorders, and immune dysfunction.

Aside from the main organs that make up the immune system (such as the skin, spleen, lymph nodes, and intestines), other parts of the body that may not be considered part of the system also play a role in its function. One such part is the vagus nerve. But what is the vagus nerve, exactly? And what is the role of the vagus nerve in immune regulation? Read on to learn more.

What is the vagus nerve, and why is it important?

The vagus nerve is one of 12 cranial nerves in the body. Cranial nerves connect the brain and the rest of the body. The nerves come in pairs, meaning there are two of each type. This is because both sides of the brain, the left and the right, must connect to the rest of the body. Each pair of cranial nerves is designed to help with sensory function, motor function, or both. The vagus nerve is one of the cranial nerves that influence both elements.

In scientific classification, the vagus nerve is referred to as cranial nerve X. All other cranial nerves are assigned a Roman numeral for identification purposes. The vagus nerve is also known as the pneumogastric nerve.

As with other cranial nerves, there are technically two vagus nerves – one for each side of the body. They are the longest cranial nerves, starting at the brain and running down through the body to the large intestine on both the right and left sides. (In Latin, vagus means wandering.) From the brain to the large intestine, the vagus nerves pass through the neck, chest, heart, lungs, and digestive tract.

The vagus nerve is part of the autonomic nervous system, which is the part that controls actions we don’t have to think about. There are two aspects of the autonomic nervous system: the parasympathetic and sympathetic nervous systems. They influence unconscious activities such as breathing, digestion, and heart rate.

Image by Nhia Moua on Unsplash: What does the vagus nerve stimulate?

What does the vagus nerve regulate?

The vagus nerve's influence on the autonomic nervous system determines what it regulates. The vagus nerve affects several organs and organ systems, including the:

• Heart
• Digestive organs
• Lungs
• Psychological brain
• Muscles
• Immune system

The gut-brain axis – the link between the gut and the brain – is also connected by the vagus nerve.

The functions that take place in the body because of the vagus nerve include:

• Breathing
• Digestion
• Heart rate
• Mood
• Blood pressure
• Immune response
• Mucus and saliva production
• Sensations in the skin and muscles
• Speech
• Urine output
• Taste

Because the vagus nerve plays a role in many functions that we don’t consciously control, it’s vital to survival.

The vagus nerve and the inflammatory reflex

The inflammatory reflex is part of the immune system, working to regulate how the system responds to injuries and pathogens. It relies on signaling carried out by the vagus nerve. Hormone secretion and neurotransmitters are influenced by proper communication from the brain through the vagus nerve to help regulate stress response and inflammation.

The reflex activates proinflammatory proteins known as cytokines in response to foreign invaders, disease, or injury. These cytokines alert the immune system and cause inflammation in the affected area so that other immune cells know where to go to fight off infection.

There is a strong connection between the two because, as mentioned above, vagus nerve signaling helps control how the inflammatory response occurs in the body. In some cases, that signal can be off.

The nerve’s influence is so strong because it affects all the other organs that play a role in immunity. For example, the vagus nerve plays a role in the secretion of specific enzymes needed during the inflammatory immune response. Some research suggests that chronic inflammation may be related to decreased vagus nerve activity.

Essentially, when the vagus nerve doesn’t signal properly, everything else in the body goes off the rails.

Image by Robina Weermeijer on Unsplash: Why is the vagus nerve important?

How does the vagus nerve reduce inflammation?

Since the vagus nerve can play a role in increased inflammation, it’s thought it can also reduce inflammation – if you can figure out how to activate it. Vagal tone is the strength of the vagal response, and while some have more active vagus nerves than others, you can actually switch yours on if you know how! By doing so, you can reduce inflammation.

There are a couple of ways to stimulate the vagus nerve to curb inflammation, including:

• Deep belly breathing: This involves slowly breathing deeply from the abdomen, filling the rib cage with air. To perform this, aim for six slow breaths per minute and on the exhale, allow the air to creep out slowly, making the exhale longer than the inhale.
• Vagus nerve stimulation: Mild electrical currents are sent from the brain into the vagus nerve using a device like a pacemaker.

While vagus nerve stimulation can be helpful if you have a chronic issue, deep belly breathing is a simple and effective way to stimulate the nerve for better functioning at home without needing a device.

The vagus nerve controls all the key bodily functions we don’t think about, so having a healthy vagus nerve is vital to your overall health, now and as you age.

Featured image by camilo jimenez on Unsplash