What Is The Vagus Nerve & Why Should You Care?

The vagus nerve is the main nerve of our parasympathetic nervous system. Picture it as our inner nerve center.

The word vagus is Latin for “wandering,” and that’s exactly what this nerve does. It is the longest nerve of the autonomic nervous system in the human body, running from our brain stem to our colon, and it is of crucial importance in modulating both our sensory and motor  systems. 

That is because it consists of sensory and motor pathways. The former consist of the somatic, the sensations we experience in our muscles and skin, and the visceral, the sensations arising from the organs within our body.

The motor pathways stimulate a multitude of muscles, such as our heart, our mouth, and throat, and the involuntary movements which aid food moving in the digestive tract.

If you picture the information moving in the body as a network, about 80% of it moves up from the body to the brain, and only about 20% of the traffic moves from the brain to the body. That is a lot of traffic, and the vagus nerve handles the majority of it!

Important functions:

Carrying Crucial Information
The vagus nerve communicates information to the brain from vital organs, such as the liver, heart, and lungs. The messages are critical to the everyday functions of the body, such as increasing and decreasing heart rate, stimulating the production of bile and digestive enzymes, and triggering the release of hormones that regulate moods, like oxytocin and serotonin. [1]

These hormones are of primary importance in mood regulation and feelings of wellbeing. We are therefore increasingly aware that the vagus nerve and the gut can play a significant role in mood disorders. [2]

The vagus nerve is also involved in the process of retaining memories. In a study published in the Journal of Translational Medicine, scientists found rats’ ability to retain spatial and fear-based memories (created to protect them from previous negative outcomes) was strengthened with the electrical stimulation of their vagus nerve.[3]

Digestion
There is a myriad of muscle movements that facilitate the functions within our body, and the messages triggering them originate from our brain and travel down the vagus nerve.

Peristalsis is the movement within our digestive tract that pushes consumed food to our colon. Any inhibition of peristalsis can result in slower transit time and constipation.

The vagal efferents (messages from our brain to our gut that travel along the vagus nerve), together with hormones such as peptide cholecystokinin, ghrelin, and leptin determine the rate of absorption, storage, and utilization of nutrients. It is therefore a crucial regulator of appetite and also how much of the healthy food we eat actually benefits us.[4]

Immune System
The vagus nerve modulates the immune response and sends anti-inflammatory signals to other parts of the body through three pathways:

1. Hypothalamic-Pituitary-Adrenal Axis (HPA Axis): The interaction between the hypothalamus, pituitary gland, and adrenal glands is referred to as the hypothalamic-pituitary-adrenal axis or HPA axis. It determines the body’s response to stress and is the reason we produce the stress hormone, cortisol.

Regulating it can lower the post-stress amounts of cortisol.[5]

2. Vago-Splenic Pathway: In this case, the vagus nerve stimulates the splenic sympathetic nerve which in turn stimulates the release of noradrenaline and Acetylcholine.

3. Cholinergic Anti-Inflammatory Pathway: This one is mediated through the vagal afferent fibers which carry messages to the brain and prompt the release of acetylcholine to inhibit inflammatory molecules.[6]

WOW! And that’s really not everything.

But now, knowing all that… 

Is Your Vagus Nerve Damaged?

Find out how to tell and what to do about it in our friend Sarah Otto’s wonderful publication…

>>Activating The Vagus Nerve: 7 At-Home Strategies For Stress,
Anxiety, Depression, & Digestion