The vagus nerve is the longest nerve connecting your brain to your other organs. Vagus means “wandering” in Latin, and it is an apt name. This nerve wanders from your brain, along the whole route of your digestive tract, and to your heart and lungs and more!
It plays a crucial role in homeostasis, which is the complex and clever process of maintaining balance in the body, by adjusting to the changing conditions we encounter in our daily lives. A simple example is how our gut automatically responds to a big meal, a snack, or a fast.
And of course, to keep this process working effectively, our brain needs information about what is going on throughout the body. So it makes sense that 90% of the information flowing along the vagus nerve is from our organs to our brain, and only 10% from our brain to our organs. All that information allows the brain to make the adjustments necessary to stay in balance, without us ever having to think about it.
We used to think most information came out from our brains to our organs: now we know so much more!
The Gut Connection
The vagus nerve listens to and talks to the parts of the nervous system that control the contraction and relaxation of your gut wall. It also orchestrates all of the secretions from the gut and other digestive organs that enable proper digestion.
Because it innervates the whole digestive tract, an imbalance in vagal nerve function can affect any part of it, from your mouth to your rectum! People who swing between constipation and diarrhea almost invariably have a vagal nerve problem. And it likely plays a part in any digestive problem, from simple gas and bloating, to significant digestive diseases such as Crohn’s and Ulcerative Colitis.
The Gut-Brain Connection
We all recognize the gut-brain connection. We say we have “butterflies in our tummy” when anxious, or we feel “kicked in the guts” by bad news. It’s the vagus nerve that makes that happen.
We know that we make the vast majority of neurotransmitters in our gut, even though they are for use in our brains. And we now know that the vagus nerve has a major role to play too. We naturopaths find that repairing the gut is really important in repairing the brain, and science is validating this more and more.
The Mental / Emotional Connection
The polyvagal theory says that humans have two parts to our vagal nerve: dorsal and ventral. The ventral part has evolved in mammals, and when it is activated we feel positive, creative, productive and happy. In this state we are more open, trusting, communicative and generally community-minded. We can activate this when we feel safe in our environment and do things that bring us joy. The ventral vagus nerve also allows us to rest and recuperate.
The dorsal part is much older, in evolutionary terms, and is associated with being immobilized with fear, and causing feelings of apathy, helplessness and hopelessness. It is triggered by large or long-term stresses, and leaves us feeling depressed, shut-down and withdrawn. This is likely to enable us to get the rest we need to restore after periods of chronic stress.
The Weight connection
The vagus nerve stimulates the production of a hormone called Grehlin, which stimulates the appetite, and the production of growth hormone. And of course growth hormone makes you want to eat and grow! If the vagus nerve isn’t getting and giving the right feedback, we can get stuck over-producing grehlin, and gain weight.
And here’s the double-whammy: the vagus nerve also has receptors for leptin, which tells you when you have eaten enough. If this isn’t working properly, we don’t know when to stop eating!
But there’s good news: Grehlin is lowered by eating adequate protein, good fats, enough fibre, getting exercise, enough sleep, and decreasing stress.
The Heart Connection
The vagus nerve can increase or decrease the heart rate, depending on the messages the brain is receiving. Extreme fluctuations of heart rate, compared with the normal range of 60-100 beats per minute, are often an indicator that the vagus nerve isn’t working well.
The Lung Connection
Relaxing breathwork decreases a racing heart because it triggers the vagus nerve to talk to the brain, which then talks to the heart and lungs. The yoga alternate nostril breathing is a good method, as is deep diaphragmatic breathing, and there are many breathwork methods out there. Find one that suits you, to use if you experience times of increased heart rate.