What is the vagus Nerve?

{GI Tract, breathing, heart rate, immune system, endocrine, brain}

The vagus nerve is one of 12 cranial nerves in the body. It has been termed the wandering nerve and cranial nerve x as it stems from the brain to the colon.

It is responsible for many reflex actions such as sneezing and coughing and also involuntary actions such as breathing and digestion.

It forms a link between the gut-brain axis.

The vagus nerve plays a big part in your parasympathetic nervous system which is your rest-and-digest system and helps counter the effects of the sympathetic nervous system. (flight-or fight)

It also has a part in the Enteric nervous system which is responsible for the Gastrointestinal tract. The Enteric nervous system communicates with the central nervous system, they work together to control things like immune function for bacteria and blood flow.

What is vagal tone?

Vagal tone refers to how well your vagus nerve is functioning and is measured indirectly by heart rate variability which is the amount of time between heartbeats. The more variable the time is in between heartbeats, the better your vagal tone.

Poor vagal tone can show through digestive issues, reflux, GERD, constipation, anxiety, IBS and IBD and much more, emotional dysregulation and more.

The vagus nerve route is probably the fastest and the most direct way for the interplay between the gut microbes and the brain.

Vagal fibers can sense various intestinal information and pass the signals on.

A low vagal tone has been described in those with IBD and IBS. Using Vagal tone stimulation, which has anti-inflammatory properties, would help to restore balance in the microbiota-gut-brain axis.


Vagus nerve damage

The Vagus nerve can be damaged. Some symptoms as a result can be:

  • difficulty speaking
  • change of voice
  • difficulty swallowing
  • gag reflex loss
  • low blood pressure
  • slow or fast heart rate
  • changes in the digestive process
  • vomiting
  • abdominal bloating or pain
  • depression and anxiety in people with breathing problems or heart disease

Vagus nerve stimulation


The term “vagus nerve stimulation” is generally used to describe any technique that stimulates the vagus nerve.

  • exercise
  • humming
  • singing
  • cold exposure
  • listening to music
  • deep breathing
  • massage
  • socializing
  • good nutrition and probitotics


  1. Howland RH. Vagus Nerve Stimulation. Curr Behav Neurosci Rep. 2014 Jun;1(2):64-73. doi: 10.1007/s40473-014-0010-5. PMID: 24834378; PMCID: PMC4017164.
  2. Breit S, Kupferberg A, Rogler G, Hasler G. Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders. Front Psychiatry. 2018 Mar 13;9:44. doi: 10.3389/fpsyt.2018.00044. PMID: 29593576; PMCID: PMC5859128.
  3. Bonaz B, Sinniger V, Pellissier S. Vagus Nerve Stimulation at the Interface of Brain-Gut Interactions. Cold Spring Harb Perspect Med. 2019 Aug 1;9(8):a034199. doi: 10.1101/cshperspect.a034199. PMID: 30201788; PMCID: PMC6671930.
  4. Han Y, Wang B, Gao H, He C, Hua R, Liang C, Zhang S, Wang Y, Xin S, Xu J. Vagus Nerve and Underlying Impact on the Gut Microbiota-Brain Axis in Behavior and Neurodegenerative Diseases. J Inflamm Res. 2022 Nov 9;15:6213-6230. doi: 10.2147/JIR.S384949. PMID: 36386584; PMCID: PMC9656367.
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