Oxidation is a natural chemical reaction that occurs in both plants and animals. The reactions produce substances that can damage tissues and lead to disease. Both plants and animals maintain complex systems of antioxidants, including vitamins, which minimize tissue damage and aging. Unlike plants and many animals, people must consume most of their antioxidants through food. Some foods, especially processed and fried varieties that contain saturated fat and hydrogenated oils, cause more oxidation and potentially more harm.
Antioxidants
Oxidation causes transferring of electrons from a substance to an oxidizing agent, which often produces free radicals. Free radicals start chain reactions that damage cells, which leads to tissue deterioration, aging and potentially cancer. The amount of oxidation a substance causes is referred to as oxidative stress, and high levels have been linked to cardiovascular and neurodegenerative diseases, according to "Biochemistry of Human Nutrition." Antioxidants can inhibit some oxidation reactions and stop the chain reactions by removing free radical intermediates. Antioxidants the body uses include glutathione, peroxidases, enzymes, vitamins C and E and carotenoids. Lack of antioxidants causes increased oxidative stress, which often leads to disease.
Vitamin C
Vitamin C, or ascorbic acid, is a powerful antioxidant that can counteract the process of certain fats being converted by oxidation into dangerous peroxides, according to "Biochemical, Physiological and Molecular Aspects of Human Nutrition." Vitamin C also eliminates the free radicals that are produced from a variety of biochemical and metabolic reactions. Excessive free radicals can damage blood vessels and organs, which accelerates the process of aging. Vitamin C may also mitigate the effects of environmental toxins. Unlike most other animals, people cannot synthesize vitamin C within their bodies. Rich sources of natural vitamin C include rose hips, strawberries, citrus fruits and peppers.
Vitamin E
Vitamin E is a group of eight substances, divided into four tocopherol types and four tocotrienol types. Alpha-tocopherol is the most studied form of vitamin E and considered the most bio-available to the body, according to "Vitamins: Fundamental Aspects in Nutrition and Health." Alpha-tocopherol is a powerful antioxidant that eliminates free radicals and displays anti-inflammatory effects. Gamma-tocopherol has the additional ability of inhibiting nitric-oxide-derived free radical formation, which may be related to the development of heart disease. Tocotrienols have not been well studied, although a 2004 study published in the journal "Annals of the New York Academy of Sciences" indicates that they may be the most potent types of vitamin E antioxidants, especially for protecting neurons from oxidative damage. Good sources of vitamin E include most nuts and seeds, plant-based oils, avocados and egg yolks.
Beta-Carotene
Beta-carotene is a carotenoid, not a vitamin, but it is a required pre-cursor in the formation of vitamin A. Beta-carotene is also a strong antioxidant, especially for the small blood vessels and delicate tissues of the eye. According to "Human Biochemistry and Disease," beta-carotene's antioxidant properties may play an important role in the prevention of age-related macular degeneration and cataracts. Other carotenoids, such as lutein and zeaxanthin, are other powerful antioxidants important for healthy vision. Rich sources of cartenoids include carrots, sweet potatoes, kale and spinach.
References
- "Biochemistry of Human Nutrition"; George Gropper; 2000
- "Biochemical, Physiological and Molecular Aspects of Human Nutrition"; Martha Stipanuk; 2006
- "Vitamins: Fundamental Aspects in Nutrition and Health"; G. Combs; 2008
- "Annals of the New York Academy of Sciences"; Tocotrienol: The Natural Vitamin E to Defend the Nervous System?; Chandan K. Sen et al.; December 2004
- "Human Biochemistry and Disease"; Gerald Litwack; 2008
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