Cigarette smoke, pollutants, sunlight, radiation and even emotional stress can cause free radicals and free radical chain reactions. Many people have been taught over the years to take megadoses of vitamin C. Much of this has been the result of the work of Dr. Linus Pauling, and the observation that humans, monkeys, and guinea pigs are among the few mammals that don't metabolize their own vitamin C from glucose. There is no debate about the essential nature of this vitamin, scurvy is a well known deficiency disease. Vitamin C is an important antioxidant, but not the only one. Humans have a wealth of antioxidant nutrients provided to them in plant and animal foods, and we have antioxidant enzymes not found in all of the animal kingdom.
Humans have one of the longest natural life spans of higher order creatures.
Our natural antioxidant processes compensate for one another, covering up momentary deficiencies by their overlap. Perhaps our very best result comes from maintaining all of our antioxidation resources to work towards our good health. A symphony orchestra produces sounds so much more harmonious than merely having 20 drums playing. It is not the quantity, but the blend. They protect against all types of free radicals and reactive oxygen species.