The vagus nerve is an essential part of the brain–gut axis and plays an important role in the modulation of inflammation, the maintenance of intestinal homeostasis, and the regulation of food intake, satiety, and energy homeostasis. Vagal tone can influence food intake and weight gain. Furthermore, the vagus nerve plays an important role in the pathogenesis of psychiatric disorders, obesity and inflammatory diseases.
The thyroid is controlled by branches of the vagus nerve. From the other side, hypothyroidism has an effect on the vagus nerve and this can lead to slowing movement through the intestines.
The interaction between the gut and the brain is based on a complex system that includes not only neural but also endocrine, immune, and humoral links.
Problems arise when vagus is underactive or inactive, or over-reactive to ordinary stimuli. If the vagus nerve is not healthy it cannot balance sympathetic nervous system and reset immune system which can lead to all kind of health conditions associated with chronic inflammation.
Working with vagus nerve can be achieved by its stimulation and some meditation techniques, which have therapeutic effect by its soothing and anti-inflammatory properties.