As humans we don't create vitamin C to meet the functional needs of stress that we face via daily living, exercise and other stressors.
A study showed that supplemental vitamin C can help runners lower stress response. We have long known that exercise increases free radical damage to the body via ROS production (Reactive Oxygen Species) and other metaboic byproducts of metabolism.
Well vitamin C, appears to confer a double protection:
Immediately post race, marathoners serum cortisol and plasma adrenaline were significantly lower in the runners supplemented with vitamin C.
Int J Sports Med. 2001 Oct;22(7):537-43.
