Protective role of vitamin E in biological systems

Article Abstract:

Cells and tissues of the body use oxygen to generate the energy that the body needs to sustain life and carry out normal functions. However, when cells use oxygen to make energy, substances called oxygen radicals (highly reactive atoms with unpaired electrons) are produced. Oxygen radicals destroy cell membranes, cause tissue damage and are believed to play a role in diseases that involve tissue degeneration. The body makes several enzymes that serve to protect cells from this type of damage. In addition to these protective enzymes, certain vitamins (called antioxidant vitamins) have been shown to protect cells and tissues from damage. Vitamin E is an antioxidant vitamin that can protect cells from the harmful effects of oxygen radicals. Research has suggested that vitamin E may have beneficial effects in protecting against oxygen radical tissue damage that occurs during the normal aging process, arthritis, cancer, cataracts, and lung injury caused by air pollution. Also, studies have shown that during strenuous exercise, levels of oxygen radicals double or triple in the muscle and liver, and that the body uses vitamin E during exercise. In summary, there is increasing evidence that oxygen radicals are involved in many different disease processes and that antioxidant vitamins, such as vitamin E, play an important protective role in slowing or preventing these disease processes. Although the Recommended Dietary Allowance (RDA) for vitamin E is 15 IU (international units) per day, increasing the intake of vitamin E over this amount may be beneficial in protecting body tissues against oxygen radical damage. (Consumer Summary produced by Reliance Medical Information, Inc.)

Prevention, Lipid peroxidation, Active oxygen in the body

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Role of oxygen free radicals in ischemic and reperfused myocardium

Article Abstract:

Oxygen free radicals (atoms of oxygen containing unpaired electrons) are highly reactive molecular species that are generated during certain biochemical reactions (the reduction of oxygen to hydrogen peroxide, for example). Oxygen radicals cause tissue damage by destroying cell membranes. In the heart muscle (myocardium), there is a delicate balance between the generation of antioxidants (compounds that inactivate free radicals) and the concentration of these oxygen radicals. When this balance is disturbed, the myocardium can be damaged. During myocardial ischemia (reduced blood flow and oxygen delivery to the heart), oxygen radicals can be generated. These radicals may come from activated neutrophils (white blood cells), metabolism of arachidonic acid (an unsaturated fatty acid in cell membranes), and oxidation of catecholamines (compounds that regulate heart rate) released from the myocardium during ischemia. During myocardial reperfusion (restoration of blood flow to the heart), oxygen radicals may be generated. In animal models of myocardial ischemia, vitamin E (an antioxidant) reduced damage to heart tissue, while peroxides (generators of oxygen radicals) increased myocardial damage. These preliminary findings indicate that oxygen radicals may play a role in tissue damage occurring during myocardial ischemia. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, Coronary heart disease, Reperfusion injury

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Antioxidant defense systems: the role of carotenoids, tocopherols, and thiols

Article Abstract:

Free radicals (unstable atoms with unpaired electrons) are by-products of certain biochemical reactions occurring within the body's cells. These free radicals are highly reactive (reactive oxygen species) and can damage DNA, proteins and cell membranes. Antioxidants such as carotenoids (including vitamin A precursors), tocopherols (vitamin E) and thiols (compounds containing sulfur) protect tissues from damage by inactivating reactive oxygen species. The ability of antioxidants to act as scavengers (inactivators) of free radicals may be important in explaining the possible anti-cancer properties of beta-carotene, a form of vitamin A and a carotenoid. Tocopherols are fat-soluble antioxidants that provide the greatest protection for cell membranes from destruction by oxygen radicals. The concentration of vitamin E in a cell membrane determines the susceptibility of the membrane to damage by free radicals. Glutathione is the most important cellular thiol for scavenging free radicals. Carotenoids, tocopherols and thiols are the natural defense mechanisms of the cell, protecting it from the damaging effects of free radicals. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Thiols, Carotenes

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