02.09.07
Antioxidants
Antioxidants are chemicals that reduce the rate of oxidation reactions. Oxidation reactions are chemical reactions that involve the transfer of electrons from one substance to an oxidizing agent. Antioxidants can slow these reactions either by reacting with intermediates and halting the oxidation reaction directly, or by reacting with the oxidising agent and preventing the oxidation reaction from occurring.
Antioxidants are particularly important in organic chemistry and biology. All organisms maintain a reducing environment inside their cells and contain complex systems of antioxidants to prevent damage by oxidation. These antioxidants include glutathione and ascorbic acid and these chemicals are substrates for enzymes such as peroxidases and oxidoreductases. Low levels of antioxidants or inhibition of antioxidant enzymes causes oxidative stress and may damage or kill cells.
Antioxidants are widely used as ingredients in dietary supplements used for health purposes such as attempting to prevent cancer and heart disease. Studies have suggested antioxidant supplements has benefits for health, but several large clinical trials did not demonstrate a definite benefit for the formulations tested, and excess supplementation may even be harmful.
List of antioxidants in vitamins:
Vitamin A (Retinol), also synthesized by the body from beta-carotene, protects dark green, yellow and orange vegetables and fruits from solar radiation damage, and is thought to play a similar role in the human body. Carrots, squash, broccoli, sweet potatoes, tomatoes (which gain their color from the compound lycopene), kale, seabuckthorn, collards, cantaloupe, peaches and apricots are particularly rich sources of beta-carotene.
- Vitamin C (Ascorbic acid) is a water-soluble compound that fulfills several roles in living systems. Important sources include citrus fruits (such as oranges, sweet lime, etc.), green peppers, broccoli, green leafy vegetables, black currants, strawberries, blueberries, seabuckthorn, raw cabbage and tomatoes. Linus Pauling was a major advocate for its use.
- Vitamin E, including Tocotrienol and Tocopherol, is fat soluble and protects lipids. Sources include wheat germ, seabuckthorn, nuts, seeds, whole grains, green leafy vegetables, vegetable oil, and fish-liver oil. Recent studies showed that some tocotrienol isomers have significant anti-oxidant properties.
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