Vitamin C has many roles in the body including antioxidant activity and collagen synthesis. "Oxidation" or free radical damage (from pollution, stress, smoking, internal processes etc) has long been established as the process that causes "aging" and can cause DNA damage. Vitamin C protects the skin from damaging effects of the sun and is also vital for collagen synthesis, without which the skin will wrinkle, form sunspots and sag as we age.