Antioxidant

An antioxidant is a chemical that prevents the oxidation of other chemicals. In biological systems, the normal processes of oxidation (plus a minor contribution from ionizing radiation) produce highly reactive free radicals. These can readily react with and damage other molecules, but the presence of extremely easily oxidisable compounds in the system can "mop up" free radicals before they damage other essential molecules.

The following vitamins have shown positive antioxidants effects:

• Retinol or Vitamin A

• Ascorbic acid (vitamin C) is a water-soluble compound that fulfills this role, among others, in living systems.

• vitamin E (tocopherol) is fat soluble and similarly protects lipids.

• selenium

Several food additives (including ascorbic acid and tocopherol-derived compounds) are used as antioxidants to help guard against deterioration of food. (see: preservative)