For decades, scientists believed that the sole purpose of the vagus nerve was to serve as a modulator in the parasympathetic nervous system.
However, new evidence suggests that this system is involved in several physiological functions, more than initially thought.
The new studies suggest that the vagus nervous system is strongly connected to the gut nerves, which explains the pathophysiology of several diseases, including irritable bowel syndrome (IBS), especially during acute flareups where stress leads to digestive symptoms.
In this article, we will cover the major benefits of an optimally-functioning vagus nerve and how it can affect the digestive health, immune system, and mental well-being.
The benefits that a well-functioning vagus nerve has to offer
The main way that the vagus nerve improves digestive health is by the regulation of inflammation, which is the cornerstone of most gastrointestinal pathologies.
In one study, scientists found that stimulating the vagus nerve for 5 days (3h sessions) of laboratory rats resulted in a significant drop in inflammatory markers and improved symptoms of colitis (colon inflammation).
These anti-inflammatory properties extend beyond the digestive tract, as patients with other inflammatory conditions, such as rheumatoid arthritis and vasculitis, may also benefit from the reduction in proinflammatory cytokines (e.g., TNF alpha, IL-1, IL-6).
Immune system optimization
The digestive tract houses a variety of microorganisms that compose the microbiota, which partially controls immune and inflammatory responses to foreign pathogens.
Additionally, the vagus nerve is an important component in controlling the immune response through complex neuroendocrine-immune pathways to modulate and optimize the inflammatory reaction via three different methods:
- The activation of the hypothalamic-pituitary-adrenal axis to exert immunomodulatory properties.
- The release of acetylcholine to regulate the action of macrophages by the vagus nerve endings.
- The activation of the splenic sympathetic nerve to halt inflammation by the release of norepinephrine.
Interestingly, scientists found a solid correlation between the activity of the vagus nerve and the mental health of patients.
This is mediated by the modification of the gut microbiome, which is thought to have a great influence on psychiatric maladies such as major depressive disorder (MDD), post-traumatic stress disorder (PTSD), and generalized anxiety disorder (GAD).
Researchers believe that activities that contribute to stimulating the vagus nerve and/or improving the biological composition of the microbiome can improve symptoms of mental illness and may even lead to complete remission.
For instance, MDD patients improved their depressive symptoms after a few sessions of vagus nerve stimulation (VNS), which led researchers to conclude that “The benefit of VNS in depression might be due to the inhibitory action on the production of proinflammatory cytokines and marked peripheral increases in anti-inflammatory circulating cytokines.”
The vagus nerve is a crucial entity that ensures several physiological functions, and scientists keep unveiling new discoveries about the benefits of this system.