Results from an ongoing 25-year study on the effects of reduced calorie consumption on monkeys showed that a calorie-restricted diet reduces the risk of mortality as well as developing age-related diseases.
This study began in 1989 at the University of Wisconsin-Madison and was one of the two ongoing projects aimed to discover the implications of a calorie-restricted diet to primates. The researchers focused on 76 rhesus monkeys. Between ages seven to 15, they were given a diet that was reduced in calories by 30 percent. The other group of monkeys was allowed to eat to their heart's content, and this group showed a 2.9 percent increased risk of diseases and a 300 percent increased risk of death.
The experiment was also tested in flies, yeasts, and rodents, in which they found out that reducing calorie intake while supplying sufficient amounts of nutrients prolonged their lifespan by 40 percent. Researchers have been studying the different effects of calorie in various organisms.
"We think our study is important because it means the biology we have seen in lower organisms is germane to primates," a professor of medicine at the School of Medicine and Public Health and one of the founders of the study, Richard Weindruch said in a press release. "We continue to believe that mechanisms that combat aging in caloric restriction will offer a lead into drugs or other treatments to slow the onset of disease and death."
However, the results of a reduced calorie diet on primates are still subjects for debate. In 2012, the National Institute on Aging reported that out of 120 monkeys, there were no significant differences between the group that was fed with fewer calories and the group that ate as much as they wanted.
Senior scientist from the Wisconsin Primate Center, Ricki Colman explained that the difference in results may have stemmed from the methodology of the study.
"In Wisconsin, we started with adults. We knew how much food they wanted to eat, and we based our experimental diet on a 30 percent reduction in calories from that point," Colman said in a press release. By comparison, the NIA monkeys were fed following the guidelines made by the National Academy of Science.
This study was published in the April 1 issue of Nature Communications.