Free radicals are atoms or groups of atoms with an odd number of electrons and can be formed when oxygen interacts with certain molecules. Once formed these highly reactive radicals can start a chain reaction. Their chief danger comes from the damage they can do when they react with important cellular components such as DNA, or the cell membrane. To prevent free radical damage the body has a defense system of antioxidants.
Antioxidants are molecules which can safely interact with free radicals and terminate the chain reaction before vital molecules are damaged. Although there are several enzyme systems within the body that scavenge free radicals, the principle micro nutrient (vitamin) antioxidants are vitamin E, beta-carotene, and vitamin C. Additionally, selenium, a trace metal that is required for proper function of one of the body's antioxidant enzyme systems, is sometimes included in this category. The body cannot manufacture these micro nutrients so they must be supplied in the diet.
Vitamin E : nuts, seeds, vegetable and fish oils, whole grains (esp. wheat germ), fortified cereals, and apricots.
Vitamin C : Ascorbic acid is a water soluble vitamin present in citrus fruits and juices, green peppers, cabbage, spinach, broccoli, kale, cantaloupe, kiwi, and strawberries.
Beta-carotene is a precursor to vitamin A (retinol) and is present in liver, egg yolk, milk, butter, spinach, carrots, squash, broccoli, yams, tomato, cantaloupe, peaches, and grains. (NOTE: Vitamin A has no antioxidant properties and can be quite toxic when taken in excess.)Research now shows that we can substantially affect the level of anti-oxidants in our bodies by eating fresh fruits and vegetables.
Google "antioxidants for crps" to learn more.