Improving vagul tone can improve the function of the parasympathetic nervous system.
Your vagal nerves are part of your body’s nervous system. They play important roles in involuntary sensory and motor (movement) functions, including:
Digestion.
Heart rate, blood pressure and respiration (breathing).
Immune system responses.
Mood.
Mucus and saliva production.
Skin and muscle sensations.
Speech.
Taste.
Urine output.