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  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

admin2012-01-27  37
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.
What is the result of the Cochrane Collaboration’s research?
选项 A、Antioxidants can be harmful to human body.
B、Antioxidants can help prevent some diseases.
C、Vitamins are dangerous to human body.
D、Antioxidants are essential to human body.
答案A
解析 根据题干中的the Cochrane Collaboration将本题出处定位到第三段末三句。该处的Conclusion说明之后的内容为研究的结果，即“我们没有发现任何证据表明补充抗氧化剂有初级预防或二级预防的作用，而维生素A和E有可能提高死亡率。”之后的两句话也在解释抗氧化剂导致死亡率上升，因此可以得出，抗氧化剂对人体有害，故答案为[A]，同时排除[D]“抗氧化剂对人体是必须的”。[B]“抗氧化剂可以阻止某些疾病”与以上的结论矛盾。[C]是针对文中的Vitamin A and E may increase mortality设的干扰项，说法太绝对。
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