What is the vagus nerve, and how does cannabis affect it?


You may have heard that our bodies impact our thoughts, and our thoughts impact our bodies. In popular wellness culture, this is called the ‘mind-body connection.’ While many systems are at play in this interaction, there is one part of our body that is largely responsible for the communication between our bodies and brains: the vagus nerve. 

What is the vagus nerve?

The vagus nerve is the tenth cranial nerve [*] that starts in the brain and travels through the neck, chest, and abdomen, touching many of the major organs on the way [*]. This nerve plays a vital role in influencing metabolic homeostasis, or, in other words, balance in the body [*]. 

The vagus nerve is part of the autonomic nervous system [*], and its primary function is to convey information about the organs (such as the gut, liver, and heart) to the brain [*]. According to researchers Breit et al., the vagus nerve is the main component of the parasympathetic nervous system, also known as the body’s ‘rest and digest’ state. When the body is relaxed and at ease in the parasympathetic nervous system, it helps to influence bodily functions by regulating mood, immunity, digestion, and heart rate [*]. Not only does the vagus nerve help to encourage homeostasis in the body, it also creates a connection between the brain and gastrointestinal tract [*], greatly influencing the gut, the brain, and even inflammatory responses [*]. 

How does the vagus nerve potentially impact health?

Since the vagus nerve travels through the gut, it influences the enteric nervous system (ENS), meaning the nervous system of the gastrointestinal tract [*]. The ENS contains roughly 100 - 500 million neurons -- “the largest accumulation of nerve cells in the human body” [*]. The ENS compares to the brain in terms of its chemicals, function, and structure [*]. As such, it’s often referred to as ‘the second brain’ [*].

The central nervous system (CNS) and the ENS interact in what is called the brain-gut axis [*]. This axis is made up of the brain, the spinal cord, the autonomic nervous system, and the hypothalamic–pituitary–adrenal (HPA) axis [*]. The gut and the brain communicate bidirectionally through the gut-brain axis using the vagus nerve as a pathway [*]. 

There is growing research that indicates the way in which gut microbiota -- a population of microorganisms in the gastrointestinal tract [*] -- produce neurotransmitters that may play a key role in staying healthy and avoiding disease [*]. In the case of the gut-brain axis, gut microbiota interact through the vagus nerve in two ways: When the spinal and vagal neurons carry feedback from the intestines to the brainstem, it helps to influence the hypothalamus and limbic system, which can regulate emotions [*]. When the spinal and vagal neurons carry feedback from the brainstem to the intestines, it helps to influence the gut’s ENS, which can regulate gut functions, such as digestion and immune response [*].

So how can this feedback loop potentially impact health? 

The activity of our vagal nerve is called ‘vagal tone’ [*]. Since the gut sends messages to the brain and vice versa, the vagus nerve impacts both our mental and physical health [*].

When we have weak vagal tone, we generally have poorer mental health and resilience, and when we have strong vagal tone, we generally have better mental health and resilience [*]. Further, vagal tone impacts our physical health; weak vagal tone is generally attributed to inflammation, whereas strong vagal tone allows us to live in the ‘rest and digest’ state of the parasympathetic nervous system more often, which can help to bring the body back into homeostasis and regulate key bodily functions vital for potential disease prevention [*]. 

How can cannabis potentially impact the vagus nerve?

When you consume cannabis, you impact the endocannabinoid system: a network of receptors that help to control key functions like mood, memory, sleep, reproduction, digestion, and appetite [*]. Cannabinoids like THC and CBD attach to receptors in the endocannabinoid system, such as CB1 and CB2, and in turn are able to produce their potentially healing effects [*].

According to a recent study titled ‘Endocannabinoids in the Gut,’  the signalling of endocannabinoids help to control the intake of food and energy by stimulating action in the vagus nerve [*]. Research also suggests that endocannabinoid receptors may play a role in “modulating the activity of vagal neurotransmission that influences gastrointestinal function” [*]. This means that cannabis may help to improve gut function since the microbiota in the gut can control specific levels of endocannabinoids by activating certain parts of the endocannabinoid system. 

Further research indicates that the neurons in the vagus nerve help to control energy and glucose metabolism [*]. The Endocannabinoid receptor CB1 is abundant in the vagal neurons, which may help to regulate gastrointestinal functions [*]. And, since we know that the vagus nerve sends messages to the brain, when the gut is happy, we’re likely to experience improved mental health [*].

How to get a Medical Document

It’s now easier than ever to get approved for medical cannabis -- all from the comfort of your own home. If your cannabis prescription is approved, you can begin purchasing cannabis from Licensed Producers such as CannMart, an online store with the widest selection of medical cannabis in Canada. To get started, create an account and schedule your online consultation with a NamasteMD nurse practitioner.