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

admin2012-01-27  53
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.
According to the first paragraph, the antioxidant is something that______.
选项 A、makes fruits and vegetables delicious
B、adds nutrition to fruits and vegetables
C、can neutralize harmful free radicals
D、can cure cancer and heart disease
答案C
解析 根据题干中的first paragraph将本题出处定位到首段。首段中的antioxidants后的内容是对它的解释，从中我们可以知道，它是一种主要在水果和蔬菜中含有的混合物，可以清除自由基，而自由基被认为是各种疾病的罪魁祸首。[C]can neutralize harmful free radicals是对文中的mop up free radicals的同义转述，故为答案。文中只是说它主要存在于水果和蔬菜中，没说它可以让水果和蔬菜美味或更有营养，故排除[A]和[B]。[D]“可以治疗癌症和心脏病”是对该段信息的过度推测，故排除。
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