An antioxidant can be defined as a molecule that has the capability to inhibit the oxidation of another molecule and thereby reduces the free radical damage. <\/p>\n\n\n\n
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Sources and origin\nof antioxidants: <\/strong><\/p>\n\n\n\n
Antioxidants are abundant in fruits and vegetables, as well as in other\nfoods including nuts, grains, and some meats, poultry, and fish. <\/p>\n\n\n\n
Beta-carotene \u00e0 foods that are orange in color, including sweet potatoes, carrots,\napricots, pumpkin, and mangoes. <\/p>\n\n\n\n
Some green, leafy vegetables, including collard greens, and spinach are\nalso rich in betacarotene. <\/p>\n\n\n\n
Lycopene \u00e0a potent antioxidant found in tomatoes, watermelon, guava, papaya,\napricots, pink grapefruit, blood oranges, and other foods. <\/p>\n\n\n\n
Estimates suggest 85% of American dietary intake of lycopene comes from\ntomatoes and tomato products. <\/p>\n\n\n\n
Selenium is a mineral, not an antioxidant nutrient. However, it is a\ncomponent of antioxidant enzymes. Plant foods like rice and wheat are the major\ndietary sources of selenium in most countries. <\/p>\n\n\n\n
Vitamin A is found in three main forms: retinol (Vitamin A1),\n3,4-didehydroretinol (Vitamin A2), and 3-hydroxyretinol (Vitamin A3). <\/p>\n\n\n\n
Foods rich in vitamin A include liver, sweet potatoes, carrots, milk,\negg yolks, and mozzarella cheese. <\/p>\n\n\n\n
Vitamin C is also called ascorbic acid \u00e0 fruits and\nvegetables and is also found in cereals, beef, poultry, and fish.<\/p>\n\n\n\n
Classification: <\/strong><\/p>\n\n\n\n
Enzymatic\nAntioxidants:<\/strong> <\/p>\n\n\n\n
Table 1:<\/strong><\/p>\n\n\n\n
\n Common Enzymatic Antioxidants<\/strong>\n <\/td>
\n <\/strong>\n <\/td>
\n Some Possible Specific Benefits or Problems<\/strong>\n <\/td><\/tr>
\n Superoxide\n dismutase (SOD)\n <\/td>
\n breakdown\n of superoxide anion, resulting in oxygen and hydrogen peroxide\n <\/td>
breakdown of hydrogen peroxide to water and oxygen. <\/td>
When infections arise, the body produces more hydrogen peroxide to help fight pathogens and heal wounds. Once the hydrogen peroxide is no longer needed, catalase breaks it down into safe compounds <\/td><\/tr>
\n Glutathione\n peroxidase (part of the glutathione system)\n <\/td>
breakdown of hydrogen peroxide and various hydroperoxides. \u00a0 <\/td>
\n The\n primary function of glutathione peroxidase is to counteract the oxidative\n attack\n <\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
vitamin C which can only be obtained through\nthe diet as it cannot be synthesized in humans <\/li>
Other non-enzymatic antioxidants include uric\nacid which accounts for almost one half the antioxidant capability of plasma,\ntocopherols which are known as vitamin E, melatonin, and glutathione.<\/li><\/ul>\n\n\n\n
Table 2:<\/strong><\/p>\n\n\n\n
Common Antioxidant Dietary Supplements.<\/strong> <\/td>
\n Some Possible Specific Benefits or Problems<\/strong>\n <\/td><\/tr>
Vitamin E Vitamin C (ascorbic acid) Selenium Zinc<\/td>
vitamin E supplementation causes a reduction in heart disease risk. All three of the major dietary antioxidants \u2014 vitamin C, vitamin E, and carotenoids \u2014 have been associated with decreased cataract risk. <\/td><\/tr>
Carotenoids Beta carotene <\/td>
High intake of beta carotene combined with vitamins C\/E and zinc has been associated with decreased acute macular degeneration in the elderly. <\/td><\/tr>
Resveratrol <\/td>
Associated with anti-inflammatory, anti-oxidant, and hypotriglyceridemic effects <\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
Clinical\nSignificance of Antioxidants:<\/strong> <\/p>\n\n\n\n
Oxidation of low-density lipoprotein (LDL) \u00e0 contribute to atherosclerosis. <\/p>\n\n\n\n
Vitamin E has been shown to have scavenging activity at the cellular level. In Cambridge Heart Institute Study (CHAOS), a randomized control trial of vitamin E in patients with known coronary artery disease showed vitamin E reduced the rate of non-fatal MI in patients with coronary artery disease. <\/strong><\/p>\n\n\n\n