Vagus Nerve: The Body’s ‘Internal Superhighway’ – What You Need to Know

“How long have you got?” is Professor Owen Epstein’s response when asked what the vagus nerve does. A pioneering consultant gastroenterologist, his areas of special interest include the role of the vagus nerve in gastrointestinal health and disease.

Like many aspects of physiology, certain areas become the focus of attention alongside genuine medical breakthroughs that advance our understanding of their importance and function. The gut microbiome, for example, went from being relatively unknown to a mainstream topic in a short period of time.

Now, the vagus nerve is experiencing a similar surge in interest. It’s only in the last 10 to 15 years that the uniqueness of this internal communication system has truly been appreciated, and only in the last five years has discussion moved from niche circles to a wider audience. Though much remains unknown, the vagus nerve is, the body’s intranet: an incredibly complex information-sharing system connecting the brain to nearly every internal organ. Just as our external environment is monitored by our senses, the vagus nerve serves as an internal surveillance mechanism.

“It has now been reasonably recognised that it is the key to providing our consciousness with information about our internal organs,” says Professor Epstein. “By providing that information in a very precise and beautiful way to the subcortical area of the brain, the vagus nerve actually orchestrates communication between the organs to try and maintain stability and wellbeing.”

The vagus nerve constantly modulates organ function, “a bit like the conductor of an orchestra,” regulating things like hunger, digestion, and the need to use the restroom. This constant modulation occurs across all organs.

The vagus nerve is one of 12 cranial nerves, but the term “nerve,” singular, is somewhat misleading. There are actually two vagus nerves, one on each side of the body, each comprising a bundle of approximately 100,000 nerves. “So you don’t technically have a vagus nerve – you have 200,000 vagus nerves,” explains Dr. Kevin Tracey, a neurosurgeon and scientist. “Each and every one of those 200,000 fibres has a specific origin in the brain or the body, a specific destination in the brain or the body, and it does a specific thing in the brain or the body – and that specific thing, that path of that fibre to do that job, was moulded and honed and refined by millions and millions of years of evolution.”

Dr. Tracey’s fascination with the vagus nerve began unexpectedly in the 1990s while researching inflammation. His team experimented with an anti-inflammatory molecule in animals that had suffered strokes. The inflammation in the brain stopped, as expected. Surprisingly, inflammation in the body also stopped, which didn’t make sense at the time.

They concluded that the vagus nerve connected the brain and body, acting as a communication pathway between the nervous system and the immune system. This connection was unexpected, as it suggested that something as complex as inflammation could be regulated by the nervous system in a similar way to how it regulates heart rate.

Understanding this connection is leading to real-world results in health outcomes across various conditions. It has led to the development of “bioelectric medicine,” treatment using devices that enable vagus nerve stimulation. By sending a specific electrical current through the nerve, the system can be “reset,” similar to rebooting a computer.

Clinical trials have shown positive results using this technique to treat epilepsy, diabetes, Crohn’s disease, fibromyalgia, irritable bowel syndrome, and recovery from stroke. Larger studies are planned for multiple sclerosis and obesity-related metabolic syndrome. Vagus nerve stimulation has also shown promise in treating depression, though results vary.

Dr. Tracey and his team have developed a device that stimulates the vagus nerve to treat rheumatoid arthritis. The SetPoint System, approved by the FDA last year, delivers daily one-minute stimulations to relieve symptoms without the risks associated with immunosuppressant drugs.

Other medical-grade devices have been developed, including non-invasive wearables like Nurosym. This type of vagal neuromodulation therapy (VNT) delivers electrical impulses through the skin of the ear, stimulating the nerve via the conch or tragus.

The vagus nerve is also important in balancing the immune system. Interfering with the nerve – blocking or cutting it – can lead to an inappropriate immune response, suggesting that autoimmune diseases may result from a faulty vagus nerve losing its modulating effect, leading to an overactive immune system that attacks its own tissues.

This connection may also relate to long Covid and post-viral fatigue syndrome, according to Professor Epstein. Often, individuals with health problems are checked for “hardware” issues – something visible on imaging. If that’s ruled out, it could be a “software” issue, an aberration in the communication superhighway, where information traveling up and down the vagus nerve is corrupted.

This also relates to PTSD and chronic anxiety, linking to the “polyvagal theory” developed by Stephen Porges. This theory describes the role of the autonomic nervous system – especially the vagus nerve – in regulating health and behavior.

Porges posited that our nervous systems move between three states: “fight or flight” (mobilization), “immobilization” (dorsal vagal shutdown), and “social engagement” (ventral vagal). The theory suggests that movement between these states is largely involuntary, and trauma can cause individuals to become “stuck” in the immobilization phase.

However, alongside legitimate medical advancements, misinformation about the vagus nerve is prevalent on social media and online. Unproven devices claiming to “tone” the vagus nerve are being marketed with limited scientific evidence. Some studies cited by these companies are small, not peer-reviewed, or lack control groups.

“It doesn’t mean that people are lying, right?” says Dr. Tracey, “but sometimes they’re selling something, and in those cases, I say: buyer beware.” He cautions against overstating claims or presenting unsupported data as fact.

While using unproven techniques is unlikely to be harmful, Dr. Tracey warns that it can undermine trust in legitimate scientific advancements. “Eventually you get to the point where people don’t believe anything anymore,” he says. “It cheapens and undermines very important and sophisticated science that has revealed how the vagus nerve works. And that’s not good for progress.”