The vagus nerve, one of the the cranial nerves and the longest autonomic nerve in the body, connects the brain to the digestive system. It is a pathway for neurotransmitters, and according to research, helps regulate inflammation in the body. Issues with vagal "tone" -- that is a low level of activity/function -- may contribute to conditions such as IBS, depression/anxiety, rheumatoid arthritis, chronic fatigue and fibromyalgia.
Disruption of gut flora (dietary factors and meds (antibiotics) can have an impact on physical and mental health. The brain-gut axis is being targeted in therapeutic approaches to treating mood and gastrointestinal disorders.
There are several ways to strengthen the function and increase the activity of the vagus nerve, such as receiving acupuncture, massage and chiropractic care. I like to reinforce my treatments by suggesting patients to combine these modalities. Other techniques are gentle yoga and exercise, chanting and meditation, laughing, singing and belly breathing. Belly breathing utilizes the diaphragm, and by expanding the diaphragm, the vagus nerve is stimulated. The results: lowered heart rate, a gentle massage of the digestive organs, and a quick switch of the mind/body into relaxation quickly (especially good in times of stress/anxiety).