The vagus nerve plays many roles in the body. Scientists think that it drives gut-brain axis communication. Recent research has linked several disorders with vagus nerve problems. In this post, we will review how this \u201cwandering\u201d nerve works and how its activity can affect health.<\/p>\n
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According to a new scientific paradigm, vagal nerve dysfunction may be at play in people with fatigue, food sensitivities<\/a>, anxiety<\/a>, gut problems, \u201cbrain fog<\/a>,\u201d and depersonalization<\/a> [R<\/a>, R<\/a>, R<\/a>].<\/p>\n Researchers suggest that these people may have lower vagal tone<\/a>–meaning the nerve has a lower ability to perform its functions. Some scientists hypothesize that vagus nerve activity can predict chronic diseases and unhealthy lifestyle choices in general [R<\/a>].<\/p>\n Although intriguing, we are still lacking solid research that would back up these hypotheses.<\/p>\n One question scientists face is which aspect of the vagus nerve is malfunctioning and to what extent it is the problem vs. other aspects of a person\u2019s biology.<\/p>\n Additionally, the majority of studies covered in this article deal with associations only, which means that a cause-and-effect relationship hasn\u2019t been established.<\/p>\n For example, just because anxiety has been linked with low vagal tone doesn\u2019t mean that and anxiety is caused by low vagal tone. Data are lacking to make such claims.<\/p>\n Also, even if a study did find that low vagus nerve activity contributes to anxiety, vagal tone is highly unlikely to be the only causative factor. Complex disorders like anxiety always involve multiple possible factors\u2013including brain chemistry, environment, health status, and genetics\u2013that may vary from one person to another.<\/p>\n That said, let\u2019s take a look at exactly what the vagus nerve does in the body.<\/p>\n The vagus nerve is part of the parasympathetic nervous system, referred to as the rest-and-digest system. It\u2019s not the only nerve in the parasympathetic system, but it\u2019s the longest one. Scientists also sometimes view it as the most important one because it has such far-reaching effects [R<\/a>].<\/p>\n The word vagus means \u201cwanderer,\u201d because this nerve wanders all over the body to reach various important organs.<\/p>\n The vagus nerve affects the brain, gut (intestines, stomach), heart, liver, pancreas, gallbladder, kidney, ureter, spleen, lungs, reproductive organs (female), neck (pharynx, larynx, and esophagus), ears, and tongue [R<\/a>, R<\/a>].<\/p>\n Given its importance for gut health, vagus nerve sluggishness or damage has been implicated in digestive disorders including dyspepsia, gastroparesis, GERD, ulcerative colitis<\/a>, anorexia, and bulimia, to name a few [R<\/a>].<\/p>\n In general, nerves (including the vagus) can be damaged or their activity altered via 3 main pathways [R<\/a>, R<\/a>]:<\/p>\n In the brain, the vagus nerve helps control mood. Limited studies suggest that its imbalance is implicated in anxiety and depression<\/a> [R<\/a>].<\/p>\n The vagus nerve thought to be largely responsible for the mind-body connection since it goes to all the major organs (except the adrenal and thyroid glands) [R<\/a>].<\/p>\n Some researchers hypothesize that this nerve might be intimately tied to how we connect with one another–it links directly to nerves that tune our ears to human speech, coordinate eye contact, and regulate emotional expressions. It also influences the release of oxytocin<\/a>, a hormone that is important in social bonding [R<\/a>].<\/p>\n One study suggested that higher vagal tone is associated with greater closeness to others and more altruistic behavior [R<\/a>].<\/p>\n Vagus activity of a child may be affected by their mother. Infants of mothers who were depressed, angry, or anxious during pregnancy had lower vagus activity in one study [R<\/a>].<\/p>\n Some studies suggested that the vagus nerve is important for getting in the mental state of “flow.” It\u2019s believed that the combination of sympathetic (fight-or-flight) and vagus activation creates the right environment for a flow state [R<\/a>].<\/p>\n Vagus nerve stimulation might increase wakefulness (by increasing orexin<\/a> in the prefrontal cortex). It has been shown to decrease the amount of daytime sleep<\/a> and rapid eye movement in epilepsy patients with traumatic brain injury. In comatose rats, it seemed to promote the recovery of consciousness after traumatic brain injury [R<\/a>].<\/p>\n However, over-activating the vagus nerve has been linked with \u201csickness behavior\u201d (fatigue, sleepiness, depression, anxiety, appetite loss, pain<\/a>, lowered motivation<\/a>, and failure to concentrate) in animals when activated by inflammatory markers in an inflammatory state (IL-1b<\/a>) [R<\/a>].<\/p>\n In the gut, it increases stomach acidity, digestive juice secretion, and gut flow. Since the vagus nerve is important for increasing gut flow (motility), having less vagus activation has been linked with IBS<\/a> risk and slower flow. Large human studies are needed to confirm these findings [R<\/a>].<\/p>\n Scientists are investigating whether stimulating the vagus nerve can increase the release of histamine<\/a> by stomach cells, which helps release stomach acid. Stomach acid releases the intrinsic factor, which helps absorb vitamin <\/a>B1<\/a>2<\/a> [R<\/a>].<\/p>\n Thus, scientists hypothesize that low stomach acidity may be, in part, a vagus nerve problem. They believe that satiety and relaxation following a meal may be partially caused by activation of the vagus nerve’s transmission to the brain in response to food intake [R<\/a>].<\/p>\n The vagus nerve is thought to be important in conditions like GERD, not only because it controls stomach acidity, but also because it controls the esophagus [R<\/a>, R<\/a>].<\/p>\n<\/a>Roles and Functions<\/strong><\/span><\/h3>\n
<\/a>Malfunction Causes<\/strong><\/span><\/h3>\n
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<\/a>How It Affects Your Body<\/strong><\/span><\/h3>\n
<\/a>Brain<\/strong><\/h4>\n
<\/a>Gut<\/strong><\/h4>\n