Restricting Calories Thwarts Disease, Aging
Study: Monkeys Fed Calorie-Restricted Diet Live Longer, Have Less Disease and Fewer Signs of Aging
July 9, 2009 -- Reducing calorie intake slows aging and significantly delays the onset of age-related problems such as cardiovascular disease, diabetes, cancer, and brain atrophy in monkeys, a new study says.
It’s likely that reducing caloric intake would have the same positive effects in people, researchers report in the journal Science.
During the 20-year study, 50% of the monkeys allowed to eat freely have survived, while 80% that ate the same foods but with 30% fewer calories remain alive, University of Wisconsin-Madison scientists say.
"This is the largest and most highly controlled study showing the beneficial effects of calorie restriction on disease and survival in a primate species," study author Ricki J. Colman, PhD, of the Wisconsin National Primate Research Center, tells WebMD. "We believe that what works in primates will work in humans because primates are so closely related to humans. This has allowed us to understand the mechanisms of the aging process."
The message for all human adults, and especially for younger people, is to reduce caloric intake permanently and you'll likely "experience the same benefits," Colman tells WebMD.
Calorie-Restricted Diet Increases Survival
The research started with 30 rhesus macaques in 1989 to chart the health effects of a calorie-restricted diet and expanded in 1994 with the addition of 46 more.
All of the animals were enrolled as adults, at ages from 7 to 14. The researchers write that of the original 76 animals in the study, 37% of the control monkeys died of age-related causes, compared to only 13% on a calorie-restricted diet.
Rhesus macaques have an average life span of 27 years in captivity, and the oldest one still in the study is 29.
Looking at overall animal health, the calorie-restricted diet leads to longer life span and improved quality of life in old age, Richard Weindruch, PhD, a professor of medicine at the University of Wisconsin-Madison School of Medicine and Public Health and co-author of the study, says in a news release.
"There is a major effect of caloric restriction in increasing survival if you look at deaths due to the diseases of aging," he says.
According to the study, the incidence of cancerous tumors and cardiovascular disease in the monkeys on a restricted diet was half that seen in the animals that were allowed to eat freely.
Although diabetes or prediabetes was seen in 42% of the monkeys that could eat all they want, it has yet to be seen in any animal on the calorie-restricted diet, the researchers say, adding that they consider this result remarkable.
"So far, we've seen the complete prevention of diabetes," Weindruch says.
Calorie-Restricted Diet Preserves Brain
Sterling Johnson, a neuroscientist and one of the researchers, says the brain health of the monkeys on a calorie-restricted diet also is better.