Antioxidants

Antioxidants are nutrients (or in fact other substances) that reduce or eliminate oxidation. In the context of nutrition, this means that antioxidants protect valuable food nutrients and essential biological molecules from destruction; an example is vitamin E protecting essential fats (omega-3 and omega-6) from oxidation in foods and also inside the body. Antioxidants reduce free radicals, which are unstable and highly destructive molecules formed by various processes, of which the most important is respiration (in other words breathing!) Other sources of free radicals include ionising radiation (which ranges from ultraviolet in sunlight to X-rays and nuclear/cosmic radiation, and there is some of the last one everywhere) and various pollutants.
Antioxidants can be split into two classes, fat-soluble (including vitamin E, beta-carotene, lycopene, zeaxanthin, lutein, and vitamin A) and water-soluble (many, including vitamin C, the anthocyanidins found in pycnogenol and bilberry extract, sulphur compounds found in garlic and broccoli, and the mineral selenium). There are a few antioxidants which can be put into both classes, such as alpha lipoic acid and the oil-soluble forms of vitamin C.
Antioxidants can help prevent or possibly reverse many problems, but chiefly those associated with aging; problems that can be helped include rheumatoid arthritis, heart disease, varicose veins, aging skin and cancer (this last is preventative only). Antioxidants in sufficient quantity can slow down the ravages of too much strong sunlight, polluted air or food with unwanted additives; antioxidants can also help recovery after exercise, by "mopping up" the extra free radicals produced during exercise, and also because many of the antioxidants are also involved in tissue building and repair, an example being vitamin C.
Antioxidants are therefore a very useful part of any supplement programme.