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Sharply cutting calories in the diets of rhesus monkeys was found to reduce aging-related deaths, according to a study that followed 76 monkeys for two decades.
The findings, published Thursday in Science magazine by researchers at the University of Wisconsin, give new impetus to researchers and companies, including GlaxoSmithKline PLC （GSK）, that are searching for a drug to mimic the beneficial effects of a meager diet in humans without the feeling of near-starvation.
For thousands of people who already attempt to sharply restrict their food intake - by as much as 30% below a normal diet of roughly 2,200 calories a day - in an effort to live longer, the findings appear to validate a technique called calorie restriction as a way to live longer.
Scientists have known since the 1930s that the technique lengthens the lives of mice. But until now, no study had shown the technique worked in monkeys, which are more genetically similar to humans. One difficulty: Monkeys live almost 30 years on average, meaning any study to measure a difference in death rates would need to wait a long time.
The Wisconsin study, which began in 1989 with 30 rhesus monkeys and added 46 more in 1994, is the first to yield a definitive finding. Researchers beg an restricting half the monkeys' diets, reducing their calories by 30%, when the monkeys were fully grown, or about 10 years old.
Thursday's findings are 'all consistent with what human practitioners of calorie restriction have always believed,' said Brian Delaney, president of the Calorie Restriction Society, which claims about 3,000 members. 'Any degree of restriction beyond what you're currently eating will confer health benefits and will slow the aging process,' he said.
After almost 20 years, 14 of 38 monkeys in the control group had died of what were considered age-related causes, such as heart disease and cancer. That compares with only five of 38 monkeys in the restricted-diet group, a significant decrease. However, the difference wasn't statistically significant when considering all causes of death, including monkeys who died from injuries and complications from anesthesia.
Calorie restriction also appeared to slow the loss of gray matter in the brain.
'It's a pretty simply story, really,' said Richard Weindruch, a Wisconsin professor who led the study. 'We've been waiting all these years for the monkeys to become old enough to get meaningful data on lifespan and brain aging and diseases.'
He is the co-founder of a Wisconsin company, LifeGen Technologies LLC, that works with drug makers to quantify the effect of possible life-extending drugs.
根据一项为期20年对76只猕猴进行的研究，大幅降低猴子饮食的热量能降低它们死于与衰老相关疾病的几率。
这份威斯康星大学（University of Wisconsin）研究人员的研究报告刊登在周四的《科学》（Science）杂志上。这些研究发现给诸多研究人员和葛兰素史克（GlaxoSmithKline）等公司带来了新的动力。这些人员和公司一直在寻找一种药物能够模拟节食给人带来的好处，又不用感受到饥饿的痛苦。
目前已经有数以千计的人尝试严格限制他们的食物摄取量──较之每天约2,200卡的正常摄入量低至多30%──以试图延长寿命。对他们来说，这项研究结果似乎证明了热量限制是一种延长寿命的手段。
自上世纪三十年代以来，科学家就已经知道这种方法能够延长老鼠的寿命。但到目前为止，还没有研究显示这种方法在猴子身上的效果，猴子和人类的基因有更多相似之处。但此类研究面临着一个困难：猴子平均可以活将近30年，这意味着任何衡量寿命差别的研究都需要等待很长时间。
威斯康辛大学的这项研究是首个得出明确结果的。研究开始于1989年，当时有30只猕猴，1994年又加入了46只猴子。当猴子长到10岁左右、发育完全成熟时，研究人员对半数猴子的饮食进行了限制，将热量摄入削减30%.
美国热量限制学会（Calorie Restriction Society）会长德拉尼（Brian Delaney）表示，周四公布的研究结果和那些身体力行热量限制的人一直坚信的信念完全一致。该学会有大约3,000名会员。他说，限制你当前的进食量，不管程度如何，都能带来健康方面的好处，能够延缓老化过程。
在大约20年后，在38只饮食不受限制的猴子中，有14只猴子死于与老化有关的疾病，例如心脏病和癌症。相比之下，另外38只饮食受到限制的猴子中，只有5只猴子死于同样的原因，差距明显。不过，在考虑所有死因之后，这种差距在统计上还不够大，因为还有猴子死于外伤以及麻醉并发症。
限制热量摄入似乎还可以延缓大脑灰质的损失。
负责这项研究的威斯康辛大学教授温德鲁奇（Richard Weindruch）说，这真的是个非常简单的结论。这些年来，我们一直在等待猴子们变得足够衰老，以获得有关寿命、大脑老化以及疾病的有价值数据。
温德鲁奇是当地一家公司LifeGen Technologies LLC的共同创始人。该公司与制药商合作，对可能延长寿命的药物成效进行量化衡量。
