CHEMISTRY IN FOCUS Do We Age by Oxidation? People (especially those over age 30) seem obsessed about staying young, but the fountain of youth sought since the days of Ponce de Leon has proved elusive. The body inevitably seems to wear out after 70 or 80 years. Is this our destiny or can we find ways to combat aging? Why do we age? No one knows for certain, but many scientists think that oxidation plays a major role. Although oxygen is essential for life, it can also have a detrimental effect. The oxygen mole- cule and other oxidizing substances in the body can extract single electrons from the large molecules that make up cell membranes (walls), thus causing them to become very reactive. In fact, these activated molecules can react with each other to change the properties of the cell membranes. If enough of these changes accumulate, the body’s immune system comes to view the changed cell as “foreign” and destroys it. This action is par- ticularly harmful to the organism if the cells involved are irreplaceable, such as nerve cells. Because the human body is so complex, it is very difficult to pinpoint the cause or causes of aging. Scientists are therefore studying simpler life forms. For example, Rajundar Sohal and his co- workers at Southern Methodist University in Dallas are examining aging in common houseflies. Their work indicates that the accumulated damage from oxidation is linked to both the fly’s vitality and its life expectancy. One study showed that flies that were forced to be sedentary (couldn’t fly around) showed much less damage from oxidation (because of their lower oxygen consumption) and lived twice as long as flies that had normal activities. Accumulated knowledge from various studies indicates that oxidation is probably a major cause of aging. If this is true, how can we protect our- selves? The best way to approach the answer to this question is to study the body’s natural defens- es against oxidation. A recent study by Russel J. Reiter of the Texas Health Science Center at San Antonio has shown that melatonin—a chemical secreted by the pineal gland in the brain (but only at night)—protects against oxidation. In addition, it has long been known that vitamin E is an antioxi- dant. Studies have shown that red blood cells defi- cient in vitamin E age much faster than cells with normal vitamin E levels. On the basis of this type of evidence many people take daily doses of vitamin E to ward off the effects of aging. Oxidation is only one possible cause of aging. Research continues on many fronts to find out why we get “older” as time passes. Foods that contain natural antioxidants.

Do We Age by Oxidation? - Cengagecollege.cengage.com/chemistry/intro/zumdahl/intro_chemistry/5e/... · 193 CHEMISTRY IN FOCUS Do We Age by Oxidation? People (especially those over

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Do We Age by Oxidation?

People (especially those over age 30) seemobsessed about staying young, but the fountain ofyouth sought since the days of Ponce de Leon hasproved elusive. The body inevitably seems to wearout after 70 or 80 years. Is this our destiny or canwe find ways to combat aging?

Why do we age? No one knows for certain, butmany scientists think that oxidation plays a majorrole. Although oxygen is essential for life, it canalso have a detrimental effect. The oxygen mole-cule and other oxidizing substances in the bodycan extract single electrons from the large mole-cules that make up cell membranes (walls), thuscausing them to become very reactive. In fact,these activated molecules can react with eachother to change the properties of the cell mem-branes. If enough of these changes accumulate, thebody’s immune system comes to view the changedcell as “foreign” and destroys it. This action is par-ticularly harmful to the organism if the cellsinvolved are irreplaceable, such as nerve cells.

Because the human body is so complex, it isvery difficult to pinpoint the cause or causes ofaging. Scientists are therefore studying simpler lifeforms. For example, Rajundar Sohal and his co-workers at Southern Methodist University in Dallasare examining aging in common houseflies. Their

work indicates that the accumulated damage fromoxidation is linked to both the fly’s vitality and itslife expectancy. One study showed that flies thatwere forced to be sedentary (couldn’t fly around)showed much less damage from oxidation(because of their lower oxygen consumption) andlived twice as long as flies that had normalactivities.

Accumulated knowledge from various studiesindicates that oxidation is probably a major causeof aging. If this is true, how can we protect our-selves? The best way to approach the answer tothis question is to study the body’s natural defens-es against oxidation. A recent study by Russel J.Reiter of the Texas Health Science Center at SanAntonio has shown that melatonin—a chemicalsecreted by the pineal gland in the brain (but onlyat night)—protects against oxidation. In addition, ithas long been known that vitamin E is an antioxi-dant. Studies have shown that red blood cells defi-cient in vitamin E age much faster than cells withnormal vitamin E levels. On the basis of this type ofevidence many people take daily doses of vitaminE to ward off the effects of aging.

Oxidation is only one possible cause of aging.Research continues on many fronts to find out whywe get “older” as time passes.

Foods that contain natural antioxidants.

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