Study: Eat Less, Live Longer?
Reported July 14, 2009
(Ivanhoe Newswire) — The bottom-line message from a decades-long study of rhesus macaque monkeys on a restricted diet is simple. Consuming fewer calories leads to a longer, healthier life.
A team of researchers at the University of Wisconsin-Madison, the Wisconsin National Primate Research Center and the William S. Middleton Memorial Veterans Hospital reports that a nutritious but reduced-calorie diet blunts aging and significantly delays the onset of such age-related disorders as cancer, diabetes, cardiovascular disease and brain atrophy.
During the 20-year course of the study, half the animals permitted to eat freely have survived, while 80 percent of the monkeys given the same diet, but with 30 percent fewer calories, are still alive.
“We have been able to show that caloric restriction can slow the aging process in a primate species,” Richard Weindruch, a professor of medicine in the UW-Madison School of Medicine and Public Health who leads the study is quoted as saying. “We observed that caloric restriction reduced the risk of developing an age-related disease by a factor of three and increased survival.”
Begun in 1989 with 30 monkeys to chart the health effects of the reduced-calorie diet, the study expanded in 1994 with the addition of 46 more monkeys. All of the animals in the study were enrolled as adults at ages ranging from 7 to 14 years. Today, 33 animals remain in the study. Of those, 13 are given free rein at the dinner table, and 20 are on a calorie-restricted diet. Rhesus macaques have an average life span of about 27 years in captivity. The oldest animal currently in the study is 29 years old.
The new report starkly emphasizes the relationship between diet and aging, according to Weindruch and lead study author Ricki Colman, by focusing on the “bottom-line indicators of aging: the occurrence of age-associated disease and death.”
The incidence of cancerous tumors and cardiovascular disease in animals on a restricted diet was less than half that in animals permitted to eat freely. Remarkably, while diabetes or impaired glucose regulation is common in monkeys that can eat all they want, it has yet to be observed in any animal on a restricted diet. Says Weindruch, “So far, we’ve seen the complete prevention of diabetes.”
In addition, the brain health of animals on the restricted diet is also better, Sterling Johnson, a neuroscientist in the UW-Madison School of Medicine and Public Health is quoted as saying. “It seems to preserve the volume of the brain in some regions. It’s not a global effect, but the findings are helping us understand if this dietary treatment is having any effect on the loss of neurons” in aging. In particular, the regions of the brain responsible for motor control and executive functions such as working memory and problem solving seem to be better preserved in animals that consume fewer calories.
“Both motor speed and mental speed slow down with aging,” Johnson explains. “Those are the areas which we found to be better preserved. We can’t yet make the claim that a difference in diet is associated with functional change because those studies are still ongoing. What we know so far is that there are regional differences in brain mass that appear to be related to diet.”
Such an observation is novel, according to Weindruch. “The atrophy or loss of brain mass known to occur with aging is significantly attenuated in several regions of the brain. That’s a completely new observation.”
SOURCE: Science, July 10, 2009