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Antioxidants are one of the hottest topics in the health field today. Numerous research studies have demonstrated the link between human health conditions and free radical damage. Countless recently published books and articles emphasize the importance of antioxidants as a key component to continuing good health. But how do you, as a health-conscious consumer, begin to understand the need for antioxidants or evaluate the seemingly endless parade of available products? In order to understand the role of antioxidants in maintaining health, we need to look first at the chemical actions of free radicals and antioxidants. Let's begin with a brief chemistry lesson.
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| What are Free Radicals? | ||
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Most stable molecules that make up ordinary substances have all their electrons paired. When a stable molecule with paired electrons gains or loses one electron, it becomes a free radical. A free radical is any chemical species with an unpaired electron. Since these free radicals are unstable, they are highly reactive and will attempt to "steal" an electron from a nearby molecule in order to regain their stability. Normal metabolic processes in the human body, such as those that turn food into energy, create free radicals by chemical reactions called oxidation reactions. You may already be familiar with some everyday examples of this type of reaction: iron rusting, cut apples turning brown, and butter going rancid are all examples of the effects of oxidation reactions. In each case, the observable effect is the result of a transfer of electrons that yields new chemical compounds. This transfer of an electron generates a new molecule that is missing one electron-a new free radical that can react with yet another molecule. A certain amount of free radical production in the human body is normal and necessary, and the body is prepared to control these products of essential cellular reactions. The body naturally produces many antioxidants, or compounds that search for free radicals and deactivate them by supplying the missing electron. You might ask, "But doesn't that then make the antioxidant missing one electron?" Well, yes it does, but the free radical formed from the antioxidant is much more stable and therefore less damaging to the body. The free radical "chain reaction" is quenched by converting harmful substances to harmless ones. Recall the browned apple used in the example above; lemon juice, which is high in ascorbic acid (vitamin C), is used to prevent this oxidative damage.
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| Where Do Free Radicals Come From and What Do They Do? | ||
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In addition to the normal amount of free radical production that results from ordinary biological processes, other sources of free radicals are inflammation, strenuous exercise, exposure to certain chemicals, radiation, alcohol, cigarette smoke, air pollutants, and high-fat diets. It is the free radical production from these sources that we need to be most concerned about, the excessive and uncontrolled free radicals that can have devastating health effects. In the body, excess free radicals may react with the molecules in cell walls, causing damage to the wall's integrity. Free radicals can also grab electrons from inside the cell, damaging the mitochondria (the cell's energy-producing structures) or disrupting the DNA code (the cell's chemical "instruction manual") in the nucleus. Peroxidation of lipids (fats) and damage to lysosomes (the cell's enzyme-containing structures) are further effects of free radical damage. In Part II of this series, we will more closely examine oxidative damage the effects of free radical destruction in the body. | ||
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