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.

    根據一項為期20年對76只獼猴進行的研究，大幅降低猴子飲食的熱量能降低它們死于與衰老相關疾病的幾率。

    這份威斯康星大學（University of Wisconsin）研究人員的研究報告刊登在周四的《科學》（Science）雜志上。這些研究發現給諸多研究人員和葛蘭素史克（GlaxoSmithKline）等公司帶來了新的動力。這些人員和公司一直在尋找一種藥物能夠模擬節食給人帶來的好處，又不用感受到饑餓的痛苦。

    目前已經有數以千計的人嘗試嚴格限制他們的食物攝取量──較之每天約2,200卡的正常攝入量低至多30%──以試圖延長壽命。對他們來說，這項研究結果似乎證明了熱量限制是一種延長壽命的手段。

    自上世紀三十年代以來，科學家就已經知道這種方法能夠延長老鼠的壽命。但到目前為止，還沒有研究顯示這種方法在猴子身上的效果，猴子和人類的基因有更多相似之處。但此類研究面臨著一個困難：猴子平均可以活將近30年，這意味著任何衡量壽命差別的研究都需要等待很長時間。

    威斯康辛大學的這項研究是首個得出明確結果的。研究開始于1989年，當時有30只獼猴，1994年又加入了46只猴子。當猴子長到10歲左右、發育完全成熟時，研究人員對半數猴子的飲食進行了限制，將熱量攝入削減30%.

    美國熱量限制學會（Calorie Restriction Society）會長德拉尼（Brian Delaney）表示，周四公布的研究結果和那些身體力行熱量限制的人一直堅信的信念完全一致。該學會有大約3,000名會員。他說，限制你當前的進食量，不管程度如何，都能帶來健康方面的好處，能夠延緩老化過程。

    在大約20年后，在38只飲食不受限制的猴子中，有14只猴子死于與老化有關的疾病，例如心臟病和癌癥。相比之下，另外38只飲食受到限制的猴子中，只有5只猴子死于同樣的原因，差距明顯。不過，在考慮所有死因之后，這種差距在統計上還不夠大，因為還有猴子死于外傷以及麻醉并發癥。

    限制熱量攝入似乎還可以延緩大腦灰質的損失。

    負責這項研究的威斯康辛大學教授溫德魯奇（Richard Weindruch）說，這真的是個非常簡單的結論。這些年來，我們一直在等待猴子們變得足夠衰老，以獲得有關壽命、大腦老化以及疾病的有價值數據。

    溫德魯奇是當地一家公司LifeGen Technologies LLC的共同創始人。該公司與制藥商合作，對可能延長壽命的藥物成效進行量化衡量。