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  3. Eat to Live A meager(不足的)diet may give you health and long life, but it’s not much fun—and it might not even be necessary. We

Eat to Live A meager(不足的)diet may give you health and long life, but it’s not much fun—and it might not even be necessary. We

admin2012-09-29  48
问题                                                             Eat to Live
   A meager(不足的)diet may give you health and long life, but it’s not much fun—and it might not even be necessary. We may be able to hang on to most of that youthful vigor even if we don’t start to diet until old age.
   Stephen Spindler and his colleagues from the University of California at Riverside have found that some of an elderly mouse’s liver genes can be made to behave as they did when the mouse was young simply by limiting its food for four weeks. The genetic rejuvenation(恢复活力)won’t reverse other damage caused by time for the mouse, but could help its liver metabolize(新陈代谢)drugs or get rid of toxins(毒素).
   Spindler’s team fed three mice a normal diet for their whole lives, and fed another three on half-rations. Three more mice were switched from the normal diet to half-feed for a month when they were 34 months old—equivalent to about 70 human years.
   The researchers checked the activity of 11,000 genes from the mouse livers, and found that 46 changed with age in the normally fed mice. The changes were associated with things like inflammation and free radical production(自由基)—probably bad news for mouse health. In the mice that had dieted all their lives, 27 of those 46 genes continued to behave like young genes. But the most surprising finding was that the mice that only started dieting in old age also benefited from 70 per cent of these gene changes.
   "This is the first indication that thee effects kick in pretty quickly," says Huber Warner from the National Institute on Aging near Washington,D.C.
   No one yet knows if calorie works in people as it does in mice, bus Spindler is hopeful. "There’s attracting and tempting evidence out there that it will work," he says.
   If it does work in people, there might be good reasons for rejuvenating the liver. As we get older, our bodies are less efficient at metabolizing drugs, for example. A brief period of time of dieting, says Spindler, could be enough to make sure a drug is effective.
   But Spindler isn’t sure the trade-off(交换)is worth it. "The mice get less disease, they live longer but they’re hungry," he says. "Even seeing what a diet does, it’s still hard to go to a restaurant and say: "I can only eat half of that’."
   Spindler hopes we soon won’t need to diet at all. His company, Life Span Genetics in California, is looking for drugs that have the effects of calorie restriction.
What can be inferred about the experiment?
选项 A、Completely normally fed mice will not experience free radical production.
B、Mice dieting in old age are not prone to diseases.
C、Mice dieting all their lives live longer.
D、Dieting doesn’t play any role in slowing down aging.
答案B
解析    短文第四段主要分析了实验的结果，该段提到“正常喂食的老鼠随着年龄的增长，体内会产生炎症和自由基；一直节食的老鼠的46个基因中有27个仍然像年轻的基因一样；老年期开始节食的老鼠受益于这些基因变化中的70%”，因此可以推断出老年期开始节食的老鼠更健康，故选B。
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