What is Vitamin C 500mg? Vitamin C is an antioxidant which is not stored in the body & needs regular topping up. Vitamin C is easily destroyed by over cooking or long storage of fresh food, or as a consequence of heavy smoking or drinking. Taking a Vitamin C supplement helps keep the bodys reserves up. What Does Vitamin C 1000mg Do? Vitamin C is an important antioxidant, which may help protect the body against free radical damage. Free radicals are chemicals which are created by our own metabolism, as well as from environmental factors such as smoking, air pollution & UV light exposure etc.. Vitamin C helps maintain healthy skin, gums & immune system.