You may have heard plenty about the gut-brain connection and how stress can show up as a bundle of nervous energy in your digestive tract. But have you ever wondered why the effects of stress can be so varied and…strange? You can thank your vagus nerve!
A quick rundown of your nervous system
The intricate system of your nerves starts in your brain and runs throughout your whole body. These nerves carry two-way messages – body to brain and brain to body.
Nerves tell the brain about what’s going on in your body – for example, pain, pressure, temperature, hunger, and where your body is in space (proprioception). They also send messages about what’s going on outside of your body from your five senses.
In return, your brain tells your body what to do – contract muscles, keep your heart beating, eat, talk, and so on. Much of this goes on without any conscious thought when you breathe, digest food and your heart continually adapts its rhythm to whatever you are doing. This is all controlled by your autonomic nervous system (ANS).
The ANS has three main divisions:
- The Enteric Nervous System (ENS) – known as the ‘second brain’, controls everything in the gut. It can act independently and due to its direct communication with the brain, either slow digestion down or speed it up.
- The Sympathetic Nervous System (SNS) contracts your heart, is active when you breathe in, and provides the fight, flight or freeze response.
- The Parasympathetic Nervous System (PNS) is active when you breathe out and creates a rest state. It also enhances digestion, although the enteric nervous system has overall control.
A lot can go wrong with our digestive function – you want just enough of all your digestive enzymes and stomach acid, the involuntary muscles in the intestines all working in concert at the right pace and rhythm.
This is where conditions such as Irritable Bowel Syndrome (IBS) and Small Intestinal Bacterial Overgrowth (SIBO) can develop, due to a disruption in the transit time of your food and also of the bacteria in your gut. Gas can ferment in the gut and cause symptoms such as bloating, flatulence, acid reflux and burping. If this affects you, you might also want to read my blog on gut fermentation.
Listening to a Spanish researcher recently talking about SIBO, he suggests from his research that the bi-directional messaging is strongest from the gut to the brain, indicating that the gut environment including the microbiome is crucial and should be prioritised. I concur with this as in my digestive health clinic that I set up in 2014, I see impressive results with digestive symptoms and consequently mood once we work on the gut environment.
Enter the Vagus Nerve
The vagus nerve is one of twelve cranial nerves that run between the brain and the body. While some cranial nerves involve the senses and some affect motor functions (movement), the vagus nerve does both. It consists of a collection of nerves that form part of your PNS extending down each side of the body.
When you feel sensations on your skin or in your muscles, that will be the vagus nerve at work. You can also have sensations much deeper amongst your internal organs too because the vagus nerve has many roles including controlling breathing, heart rate and digestion.
Those weird reflex actions that often seem to happen without your conscious control (swallowing, coughing, sneezing, vomiting) – that will be your vagus nerve too.
Your vagus nerve also controls:
- Immune response
- Mucus and saliva production
- Urine output
One of the important roles of your vagus nerve is to oppose SNS (fight or flight) activity. When we are in fight or flight too much of the time, this can negatively affect your health in many ways, including:
- High-stress hormone production reduces the production of other hormones, such as those for fertility, uncomplicated menstrual cycles, and good sleep
- Worsened blood sugar control, more cravings, and potential weight gain
- Increased inflammation, allergies, and impaired immune defenses
- Hypervigilance, high anxiety, clouded memory and brain fog
The far-reaching effects of the vagus nerve
Your digestive tract covers the whole distance between your mouth and your anus. And if it wasn’t all folded up inside your body (think of the small intestine, which is neatly folded over and over in your abdomen), that’s 30 feet of nerve connections. So when the vagal tone (the ability of the vagus nerve to do its job well) is poor it can show up as a vast array of digestive problems.
Your throat and oesophagus (food pipe) are all part of these connections too. So, under stress or extreme anxiety, some people find themselves having difficulty swallowing, a weakened gag reflex, hoarseness or losing their voice regularly.
Other signs of a sluggish vagus nerve include abdominal pain, bloating, acid reflux, dizziness or fainting, and fluctuations in heart rate, blood pressure or blood sugar levels.
So if it’s all involuntary and I can’t do anything about it, why do I need to know about the vagus nerve?
Well here’s some wonderful news. There is a lot you can do to help your vagus nerve to calm your mind and your digestive system. And this has lots of other positive effects too as you can see in the list above of what goes wrong when you spend too much time in fight or flight.
You can stimulate your vagus nerve in so many different ways, and this turns on your PNS to promote relaxation and a balance of hormones and bodily functions.
Many clinical trials have looked into the potential positive effect of vagus nerve stimulation on treatment-resistant depression but more research is needed. Initial results suggest a potential reduction for people with depression, without the usual side effects of medications.
Other research has linked anti-inflammatory effects of vagus nerve stimulation on Inflammatory Bowel Disease (Crohn’s and Colitis), reducing flares and in animal models seeing these conditions in some cases being put into remission. Research has also identified a potential for helping cardiovascular disorders.
5 ways to stimulate your vagus nerve
- Slow breathing – Voluntarily slowing your breathing down, while putting you in a rest state can also improve heart rate variability (HRV) – an important factor for your heart’s ability to adapt to changes in your body and in response to your environment. There are many different types of breathwork that help you with slow breathing, a good way to start is to find some guided breathing tracks or attend a class. If you’re a fan of yoga, the relaxation at the end of a practice is a perfect way to do this too.
- Exercise – Aerobic or cardiovascular exercise in particular helps your autonomic system to regulate your heart rate and parasympathetic activity. Regular exercise in this way can then contribute to a lower resting heart rate which is supportive of long-term health. Find types of activity that you enjoy and get your heart pumping. Great choices include brisk walking, dancing, cycling, and swimming but the options are almost limitless.
- Music – Research is ongoing into the exact ways that singing, humming, or listening to music stimulate the vagus nerve, but we all know how good we feel when we do any of these, right? Theories suggest that the vocal cords, being directly in contact with the vagus nerve stimulate it through vibrations and this soothes the nervous system.
Similarly, sound vibrations may also reach your vagus nerve along the sides of the ears. So pop your favourite tunes on, sing like nobody is listening, or join a choir. In fact, gargling has the same effect. I also recommend my clients gargle in the shower for 30 seconds to 1 minute daily.
- Cold water – If you’ve heard of the Wim Hof Method, you may know that cold water exposure has been associated with many improvements in health and well-being. While research is yet to catch up, many individuals attest to the benefits these practices provide. A quick blast of cold at the end of your shower or a splash of cold water on the face are both worth a try and safe for beginners.
- Massage – Pressure receptors under the skin can also stimulate the vagus nerves, which is why massage can be so relaxing. Plus, the great thing about massage is that there are so many different places on the body where you will experience similar benefits. Even self-massage will have the same effect, although it’s certainly a real treat to receive one from someone who knows what they’re doing!
If you are experiencing uncomfortable digestive symptoms, watch my FREE masterclass 3 Steps To Control Your Gut (And Still Eat Your Favourite Food).
Jane Barrett is a registered nutritionist and expert in digestive health helping women & children with digestive issues take control of their health through food. She offers support through meal plans, online courses & personalised 1:1 programmes on Zoom.