Understanding the Vagus Nerve:
Have you ever felt butterflies in your stomach?
Has anyone ever told you to “trust your gut”?
What about ever having experienced anxiety in addition to chronic bloating, nausea or diarrhea?
Your gastrointestinal tract and brain are deeply connected by a nerve called the Vagus Nerve. This nerve acts like a two way highway, largely responsible for the brain-gut connection. Therefore our gut talks to our brain, and our brain talks to our gut (Lipski, 2020). So if you struggle with hormone imbalance, gut issues, or even mental health disorders this post is for you!
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In utero, humans start off as a clump of tissue called an embryo. As the embryo develops, a ball of cells divides into two, forming the brain and the gut. Just because these two organs live in different regions of the body does not mean they are separate; in fact, they are connected by the Vagus Nerve. As this nerve extends down the body, it branches off into various organs through the digestive system and even parts of the reproductive system like the ovaries. Extensions of the Vagus Nerve signal electrical impulses giving instructions and communicating any sense of change happening within the nervous system to these other organs (Collen, 2015).
As part of the autonomic nervous system, the Vagus Nerve plays a role in activating the parasympathetic nervous system (PNS). You may have heard of this being referred to as “rest and digest” or “feed and breed”. The PNS impacts our emotional well being, heart rate, reproductive and digestive systems. Though many bodily functions relating to these systems are autonomic (meaning they occur involuntarily), we can actually voluntarily stimulate the Vagus Nerve, which can have profound effects on our overall well-being. The opposite of the PNS is the sympathetic nervous system (SNS), which is also known as “fight, flight, or freeze''. When we intentionally stimulate the vagus nerve, we help our nervous system exit the “fight or flight” mode.
From the gut to the brain:
The gut, also known as the “second brain” houses billions of bacteria called microbiota. These organisms also play a critical part in communicating to the Vagus Nerve by releasing neurotransmitters (chemicals) to stimulate the brain (Collen, 2015).
95% of serotonin, the “feel good” hormone, is found in the digestive tract, which helps explain the correlation between gut health’s role in mood and anxiety disorders. (Mulak, 2004).
As food passes through the esophagus and into the stomach and then small intestine, the digestive system sends nerve signals to the brain to create sensations of fullness and lowers your appetite. (Woolston, 2002).
Chronic stress can reshape the composition of the gut’s bacteria through stress hormones and inflammation. In turn, the gut bacteria releases toxins and neurohormones that can influence mood and eating habits. (Madison, 2019).
From the brain to the gut:
The Central Nervous System (the brain and spinal cord) release chemicals that tell the stomach when to produce acid during digestion, when to churn food, and when to rest. Peristalsis (involuntary contractions) in the intestines are also stimulated through similar signaling.
The Vagus Nerve stimulates accessory organs for digestion, like our salivary glands, pancreas, stomach and small intestine which release enzymes to help break down our food.
The Vagus Nerve tells the stomach to slow down while emptying food into the small intestine to induce satiety.
Activation of the Vagus Nerve reduces gastrointestinal inflammation and intestinal permeability–AKA leaky gut (Lipski, 2020).
Stress and Digestion:
I always tell my clients “when stress is on, digestion is off.”
What does this mean exactly?
Picture an animal in the wild going about their day, eating plants or other animals, resting in the sun or roaming around. During this time their PNS is activated; their nervous system perceives them as being safe. Now picture the animal being approached by a predator– maybe this is a zebra being hunted by a lion. Their nervous system quickly switches from the PNS to the SNS; they are in “fight, flight or freeze” All of the energy that was being used to previously digest their food is now being used to pump adrenaline through their body, increasing their heart rate, dilating their pupils to ultimately prime their body to get away from the predator. Once they are deemed safe, they go about their day living in the PNS again (Sapolsky, 2004).
Unlike zebras in the wild, humans don’t necessarily have that off switch where we can just forget about our stressor. Luckily our stressors aren’t life or death (most of the time), but our body does not know the difference. Our body responds to stress in the same exact way as the zebra’s body does in the wild, preparing us to get away from the predator. So when our “predator” means taking an exam in school, going to a work interview or even having a conflict with a loved one, our body can get stuck in this sympathetic dominant state. This is our body’s way of protecting us short-term. Long-term, it leads to chronic health issues such as high blood pressure, mental health disorders, hormone imbalances, blood sugar dysregulation and many symptoms impacting gut health and digestion.
Building awareness:
As mentioned above, we do have the power to consciously stimulate our Vagus Nerve. Remember- when stress is on, digestion is off. By building awareness of the state of our nervous system throughout the day, especially during meals, we can really support our digestion. One of my go-to questions when working with a client is “what are your indicators of stress?” meaning, how does your body and/or mind tell you that you may be stuck in a stress response?
Do you clench your jaw?
Maybe you feel tension in your shoulders?
Do you become irritable?
Do you struggle shutting down your mind at night when it’s time to sleep?
Or if you’re anyone like me, you catch yourself racing through the day, skipping meals and hydration, multi-tasking, scrolling a lot and not taking breaks to slow down.
Again, this is your body’s way of communicating to you– “hey, please pause. You really need to slow down and relax a bit. I can't keep up!”
When we are sympathetic dominant– meaning we are mostly in this stressed out state, we aren’t used to being calm or relaxed. It does not feel normal and might even feel uncomfortable to slow down at first. We may even thrive off our stress. But again, there are always health consequences to this, both short-term and long-term.
Vagal toning 101: It’s time to take the steering wheel!
Knowledge is power! By understanding the complexities of the gut-brain connection we can take responsibility for nurturing a healthier stress response. Even though the stress response is automatic (and can save our lives), we never want to get stuck in it.
This is where vagal toning comes in– just like starting a workout routine or building any new habit, it takes a lot of practice! Most people can’t walk into the gym and lift 50 pounds with ease, or run a half marathon the day you decide to take up running. I promise with practice and time the results start to become instantaneous. Activating the Vagus Nerve becomes easier and more natural.
Tips for stimulating the vagus nerve:
Intentional breathing: One of my favorite breathing exercises is called 4-7-8 breathing. You basically breathe in through the nose for 4 seconds, hold at the top of your inhale for 7 seconds, and then slowly exhale through the mouth as if you are blowing out of a straw for 8 seconds. You want the exhale to be longer than the inhale because that is what activates the PNS. (Have you ever hyperventilated when you felt upset or panicky? Longer Inhales activate the SNS)
Cold therapy: Try ending your shower cold for the last minute or so. If you ever feel really panicky or anxious, try holding ice cubes in your hand and watch them melt.
Singing and humming
Yoga
Meditation
Gargling
Laughing
Exercising
Acupuncture
Spending time in nature
Putting it into practice:
Can you light a candle and listen to music and sing along while you cook your dinner?
Can you take pauses to pay attention to your breathing throughout the day, whether that be in between meetings, driving to work, or when going for a walk?
Can you take 3 big belly breaths before you eat your meal?
Can you try ending your shower with cold water or rinsing your face with cold water in the morning?
Can you prop your legs up against the wall and meditate before bed?
Can you try gentle movement like walking or stretching when you get home from a long day before jumping into the next task?
Do these practices as often as you need to. With more awareness you will also learn what triggers your stress-response, so over time you can get ahead of it. Remember you are still human, so stress is normal too. But if you struggle with GI issues, always come back to these vagus nerve stimulating practices to use as tools to better support your nervous system, digestion and mental health.
Some digestive benefits you may notice quickly:
Reduced bloating
Noticing fullness sooner
Less acid reflux
Healthier bowel movements
References:
Collen, A. (2015). 10% Human: How Your Body’s Microbes Hold the Key to Health and Happiness. HarperCollins Publishers.
Lipski, L. (2020). Digestive Wellness: Strengthen the Immune System and Prevent Disease Through Healthy Digestion. Mcgraw-Hill Books.
Madison, A., & Kiecolt-Glaser, J. K. (2019). Stress, depression, diet, and the gut microbiota: human-bacteria interactions at the core of psychoneuroimmunology and nutrition. Current opinion in behavioral sciences, 28, 105–110. https://doi.org/10.1016/j.cobeha.2019.01.011
Mulak, A., & Bonaz, B. (2004). Irritable bowel syndrome: a model of the brain-gut interactions. Medical science monitor : international medical journal of experimental and clinical research, 10(4), RA55–RA62.
Sapolsky, R. (2004). Why Zebras Don’t Get Ulcers. St Martin’s Griffin.
Woolston, C. (2002). Surprising Link Between Mood and Digestion. Consumer Health Interactive. http://www.ahealthyme.com/article/primer/101186767
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