The Vagus Nerve, or tenth cranial nerve, is the longest and most complex nerve from the brain, controlling the majority of our internal organs like the heart, lungs, and digestive tract.
More specifically, the vagus nerve has the responsibility for parasympathetic control (rest and digest mode) of these organs and plays a key role in body functions like heart and breathing rates, sweating, peristalsis of the GI tract, and detoxification. Additionally, the vagus nerve controls a few skeletal muscles like those responsible for speech and swallowing.
The Digestive Tract begins in the mouth and travels down the esophagus, where the vagus nerve is necessary for swallowing, coughing, and the gag reflex (1). Further down the gastrointestinal tract, the vagus nerve is responsible for stomach acidity, gastric juices, and keeping things moving through (motility) the gut.
The gut and brain are connected through a complex communication network (gut-brain axis) and the vagus nerve is a key element here, responsible for sending signals in both directions. The majority of these signals (80%) flows from the body (gut) to the brain and about 20% of the signals flow from the brain to the body. So, poor gut health can negatively impact the brain and influence neurotransmitters, mood, and behavior and the brain can influence the secretions, microbial balance, motility, and delivery of nutrients within the gut.
For example, if the body is stressed and vagus nerve function is compromised the production of stomach acid and digestive enzymes can be suppressed, gut permeability (leaky gut) can increase, and dysbiosis (microbial imbalance) and nutrient malabsorption can occur.
Improving vagal tone (the activity of the vagus nerve) can be done each day through simple acts like deep breathing, singing, gargling, exposure to sunlight, meditation, prayer, laughing, and exercising, according to Dr. Eva Detko (2).