Our bodies are made up of billions of molecules held together by electromagnetic forces. These chemical bonds are created with paired electrons. Free radicals are unstable molecules that have lost an electron and are unbalanced. Free radicals seek to replace the lost electron by randomly attacking nearby molecules and stealing electrons. One free radical can damage a million or more molecules in a chain reaction referred to as radical propagation, which leads to oxidative stress. Uncontrolled oxidation is very destructive.

It is very simular to effects we see in our environment, such as the rusting of metal, the rotting of meat, the browning of apples or the hardening of old rubber. Oxidation in our body by free radicals is thought to be responsible for premature aging, wrinkling of the skin, hardening of the arteries, stiffening of the joints, the formation of cataracts, the initiation of cancer and much more. We are constantly exposed to free radicals via such processes as antimicrobial activity by white blood cells, sunlight, and metabolism of an unhealthy diet, stress, and pollutants. Our ability to fight free radical damage effectively is compromised by our inadequate nutritional choices or diets that contain limited amounts 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 micronutrient (vitamin) antioxidants are vitamin E, beta-carotenem and vitamin C.

Addititonally, selenium, a trace metal that is required for the proper function of one of the body's antioxidant enzyme systems, is sometimes included in this category.

Antioxidant supplementation is necessary if we are unable to reduce our exposure to free radicals, but wish to counter their effect.