The results of a 20-year-long study on caloric restriction in rhesus monkeys provides the strongest evidence yet that a low-calorie diet produces life-extending metabolic changes in primates — even, perhaps, in people.
Fed a diet that provided adequate nutrition on 30 percent fewer calories than is considered normal, the monkeys have largely escaped the ravages of heart disease, cancer and other age-related diseases.
“We’ve published before on some of the positive effects, but this is the big picture that says it works,” said Ricki Colman, a gerontologist at the Wisconsin National Primate Research Center. “This gives us what we need to look at what caloric restriction is doing to the aging process.”
Caloric restriction came to scientific attention in the mid-1930s, when Cornell researchers showed that it extended the lives of mice by about 40 percent. The feat was subsequently duplicated in many other animals, from roundworms to dogs, but until now had not been conclusively demonstrated in primates.
Despite the uncertainty, it’s estimated that several thousand people already practice caloric restriction, with several hundred doing so within carefully monitored studies. But such dietary limitation may prove undesirable or impossible for most people. Instead, scientists want to find drugs that mimic the effects of caloric restriction, and over the last decade have described some of its underlying biology.
Caloric restriction appears to trigger energy-saving metabolic changes, activating metabolic pathways involved in regulating cell growth and repair. These pathways are targeted by several drugs currently under development, including resveratrol, which has protected animals from age-related diseases and is now being tested as a diabetes treatment. Another intriguing drug is rapamycin, an immune system suppressor that — though unproven and likely unsafe for human use as a longevity enhancer — has dramatically extended the lives of elderly mice.
Research on these experimental drugs is validated by today’s findings, which suggest that effects observed in animals may be similar in people.
