Eat to Live
A meager 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 to1 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 he made to behave as they did when the mouse was young simply by limiting its food for four weeks. The genetic rejuvenation won’t reverse other damage caused by time for the mouse, but could help its liver metabolize drugs or get rid of toxins.2
Spindlers team fed three mice a normal diet for their whole lives, and fed another three on half-rations3. Three more mice were switched from the normal diet to half-feed3 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 production4 — probably bad news for mouse health. In the mice that had dieted nil 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 these effects kick in5 pretty quickly.” say Huber Warner from the National Institute on Aging near Washington D. C.
No one yet knows if calorie restriction works in people as it does in mice, but 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 is worth it6. “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 cat half of that’.” Spindler hopes we soon won’t need to diet at all. His company, Lifespan Genetics in California, is looking for drugs that have the effects of caloric restriction.
词汇: meager /5mi:^E(r)/adj.不足的 toxin /5tCksin/n.毒素 youthful /5ju:Wful/adj.有青春活力的 metabolize /mE5tAbElaiz/v.使(一种物质)进入新陈vigor /5vi^E/n.精力，活力 代谢过程 liver /5livE/n.肝脏 genetic /dVi5netik/adj.基因的 ration /5rAFEn/n.定量 rejuvenation /ri5dVu:vineiFEn/n. 恢复活力，返老还童caloric /kE5lCrik/n.卡(热量的单位) trade-off n.交换，交易 inflammation / 7inflE5meiFEn/n.炎症，发炎 rejuvenate /ri5dVu:vineit/v.恢复活力
练习：
1. According to the passage, which of the following is NOT true?
A Eating less than usual might make us live longer.
B we go on A diet when old, we may keep healthy.
C Dieting might not be needed.
D We have to begin dieting since childhood.
2. Why does the author mention an elderly mouse in paragraph 2?
A To describe the influence or old age on mice.
B To illustrate the effect of meager food on mice.
C To tell us how mice’s liver genes behave.
D To inform us of the process of metabolizing drugs.
3. What can he inferred about completely normally fed mice mentioned in the passage?
A They will not experience free radical production.
B They will experience more genetic rejuvenation in their lifetime.
C They have more old liver genes to behave like young genes.
D They are more likely to suffer from inflammation.
4. According to the author, which of the following most interested the researchers?
A The mice that started dieting in old age.
B 27 of those 46 old genes that continued to behave like young genes.
C Calorie restriction that works in people.
D Dieting that makes sure a drug is effective.
5. According 10 the last two paragraphs, Spindler believes that
A calorie restriction is very important to young people.
B seeing the effect of a diet, people will like to eat less than normal.
C dieting is not a good method to give us health and long life.
D drugs do not have the effects of calorie restriction.
答案与题解：
1. D第一段第一句讲“节食可能不是非做不可的事”，第二句讲“即使上了年纪再节食，我们仍然有可能在很大程度上保持青春活力”，因此，“我们必须从小就开始节食”是错误的， D是答案。
2. B第二段提提及“一只高龄老鼠的”时候，作者谈到“只要连续四周限制它进食，它的肝脏基因就会变得和衰老前一样充满活力”。据此，为了描述节食对老鼠所产做的影响”昀好地回答了题干中的问题。
3. D第四段提到，“正常饲养的老鼠随着年龄的增长 46条肝脏基因会发生变化，这种变化与炎症和有机体组织无限激增有关”，因此， D正确。
4. A第四段昀后一个句子讲“但昀惊人的发现是那些上了年纪才开始节食的老鼠也能从 70%的基因变化中受益”。“昀惊人的”自然是“昀令研究人员感兴趣的”。
5. C文章昀后两段谈及 Spindler对节食的看法。首先，他不能肯定节食是否值得。其次，他希望在不久的将来，我们不必节食。所以，我们可以推知，他认为节食不是值得以健康长寿的好办法。
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