Low-cal diet increases monkeys' lifespan

Researchers have found in a study that a significant reduction in mortality and in age-associated diseases was seen among the monkeys, who had calorie-restricted diets.

The study of 76 rhesus monkeys was performed at the Wisconsin National Primate Research Center in Madison. When they were 7 to 14 years of age, the monkeys began eating a diet reduced in calories by 30 percent. The comparison monkeys, which ate as much as they wanted, had an increased risk of disease 2.9 times that of the calorie-restricted group, and a threefold increased risk of death.

Restricting the intake of calories while continuing to supply essential nutrients extends the lifespan of flies, yeast and rodents by as much as 40 percent.

The effects of caloric restriction on primates have been debated. An influential 2012 report on 120 monkeys being studied at the National Institute of Aging (NIA) reported no differences in survival for caloric restriction animals and a trend toward improved health that did not reach statistical significance.

The discrepancy may be a result of how the feeding was implemented in control animals in the NIA study, say the Wisconsin researchers. Ricki Colman, a senior scientist at the Wisconsin Primate Center, who presently co-leads the project, suggests that NIA's control monkeys were actually calorie-restricted.

Coleman said that in Wisconsin, they 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. In contrast, the NIA monkeys were fed according to a standardized food intake chart designed by the National Academy of Science.

The study has been published in the journal Nature Communications.