Antioxidant - Antioxidant Antioxidants Background Oxidation...

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Antioxidant Antioxidants Background Oxidation of biomolecules is the basis of many diseases; such as cancer, heart disease, cataracts, inflammatory joint disease. The process of oxidation involves the production of free radicals and reactive oxygen species. These free radicals have unpaired electrons. They are produced internally by energy metabolism (from mitochondria), detoxification of drugs and during the immune response. They also reach the human body from external sources such as UV light, smoke, ozone and oxidized lipids in our diet. The human body has two different systems to protect itself from oxidation by free radicals. The simplest (and the one that is most amenable to dietary supplementation) is the antioxidant compounds . These compounds work by either donating an electron to the free radicals or by accepting the unpaired electron which makes the free radicals stable. In some cases, they build up of these stable radical antioxidants can act as oxidants. Some antioxidant compounds have been recognized as vitamins due to their relationship to specific diseases (vitamin C and scurvy, vitamin E and muscle degeneration) or have essential amino acids (glutathione, an antioxidant, contains cysteine). The other antioxidant system uses enzymes to inactivate or decrease the reactivity of the free radicals by changing them. Nutrients are also part of the antioxidant enzyme system (zinc with superoxide dismutase [SOD], copper and manganese with mitochondrial superoxide dismutase (SOD), selenium with glutathione peroxidase and iron with catalase). There are many compounds in nature that act as antioxidant compounds . The most prominent are the carotenoids, flavonoids and quinones. The carotenoids are pigments that give the beautiful colors to the leaves in the fall, the orange to carrots, the red to tomatoes, etc. However, recent intervention trials reported that smokers given dietary beta-carotene supplementation exhibited an increased risk of lung cancer and overall mortality. beta- Carotene has been hypothesized to promote lung carcinogenesis by acting as a prooxidant in the smoke-exposed lung. Smokers should stay away from taking dietary supplements of beta- carotene however should not avoid it in their diet. The flavonoids are associated with plant material and are often precursors of tannins (which give the astringent nature found in red
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Antioxidant - Antioxidant Antioxidants Background Oxidation...

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