2. 外语
  3. For years the media, food labels, dietitians, and even scientists who should know better have bombarded (轰炸) us with advice to l

For years the media, food labels, dietitians, and even scientists who should know better have bombarded (轰炸) us with advice to l

admin2013-05-04  30
问题     For years the media, food labels, dietitians, and even scientists who should know better have bombarded (轰炸) us with advice to load up on antioxidants: compounds found mostly in fruits and vegetables that mop up free radicals, which are highly reactive clusters of atoms that have been fingered as the evil-doers responsible for aging and for illnesses from cancer to heart disease.
    Not so fast. First, studies piled up showing that taking antioxidants—even such common and seemingly harmless ones as vitamins C and E—as supplements was not beneficial to health and might even be dangerous. Many of the free radicals that are neutralized by antioxidants perform valuable functions in the body. The most important:fighting toxins (毒素) and fighting cancer. Maybe it’s not such an excellent idea to flood the body with something that neutralizes these warriors of the immune system. Or as British chemist and science writer David Bradley noted in his blog,Reactive Reports,"It’s always struck: me as odd that you would want to absorb extra antioxidants anyway, given that oxidizing agents are at the front-line of immune defense against pathogens (病原体) and cancer cells...Suffice to say that taking antioxidant supplements... may not necessarily be good for your health if you already have health problems, especially cancer or an infection. "
    The first hints that the trend was crashing came from the hundreds of studies that have tried to assess the health effects of antioxidant supplements. The results have not been pretty. In 2008 the Cochrane Collaboration, an international organization of scientists who assess medical research, carefully checked 67 studies with nearly 400,000 participants. The goal;to determine whether antioxidant supplements reduce mortality in either healthy people or in people with diseases. Conclusion:" We found no evidence to support antioxidant supplements for primary or secondary prevention, and Vitamin A and E may increase mortality. " In analyses of antioxidant supplements and Lou Gehrig’s disease, Alzheimer’s or mild cognitive impairment, and lung cancer, the Cochrane scientists’ verdict was the same: no. And each analysis had an alarming refrain about increasing overall mortality.
    It’s not clear why antioxidants in supplement form might be so dangerous. One idea holds that at high doses they become pro-oxidants,stimulating the harmful DNA- and cell-damaging reactions they’re supposed to prevent. But a more likely explanation is that we are seeing the human version of what scientists are finding in studies of lab animals: antioxidants interfere with immune-system cells that fight infection and cancer.
The most important function of some free radicals neutralized by antioxidants is______.
选项 A、loading up on antioxidants
B、fighting toxins and cancer cells
C、protecting pathogens and DNA
D、absorbing antioxidant supplements
答案B
解析 事实细节题。定位句指出，很多被抗氧化物中和的自由基在人体中有着非常重要的功能，最重要的功能就是用来清除毒素和癌细胞，即有些自由基的最重要功能是清除毒素和癌细胞。因此，B)符合题意，故为本题答案。A)“补充足量抗氧化物”和D)“吸收抗氧化物补充物”明显错误，故排除；C)“保护病原体和DNA”，不符合原文，故排除。
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