YOU may be able to have your cake and keep eating it to a ripe old age. It鈥檚 been shown for the first time that the restricted-calorie diets known to extend the lifespans of animals might work for people too 鈥� and you may not need to go hungry to reap the benefits.
Putting animals on a near-starvation diet makes them live up to 50 per cent longer than normal. Until now, though, there was no evidence this works for primates, which of course includes us.
To find out, a team led by George Roth at the National Institute on Aging in Maryland has been studying rhesus monkeys. It鈥檚 too early to say if the monkeys on a restricted-calorie diet are living longer, but they show the same metabolic changes as rodents on the diet: lower body temperature, lower levels of insulin in the blood and less age-related decline in levels of a steroid hormone called DHEAS.
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They wondered if people who happen to have these metabolic markers lived longer. So they analysed the samples and records of men in the Baltimore Longitudinal Study on Aging, a study that has been running since 1958 in which volunteers undergo a battery of medical tests every two years. For each of the three markers, they split the records into two halves and compared survival rates (Science, vol 297, p 811). They found that men with lower body temperatures, lower insulin levels or higher levels of DHEAS did tend to live longer.
Studies directly testing the effects of a low-calorie diet on humans are already under way. If these people show the same metabolic changes, it will be strong evidence that caloric restriction works for humans too.
But it might be possible to live long without having to go hungry. The men in the Baltimore study weren鈥檛 eating low-calorie diets 鈥� some of them just happened to have the metabolic signs linked to caloric restriction. 鈥淭hey鈥檙e doing something we don鈥檛 know about, or they have good genes,鈥� says Roth.
In fact, other groups think they know the molecular mechanism behind caloric restriction, and are trying to develop drugs that mimic the effect (快猫短视频, 8 June, p 7). DHEAS is already sold in health shops, but there is no evidence that taking it makes any difference.
