Drastic limits on calorie consumption starting early in a monkey's life seemed to delay aging of the animal's immune systems in new research.
Numerous studies have found that calorie restriction can extend the life span of organisms such as yeast, worms, fruit flies, and mice. However, scientists don't know how caloric restriction lengthens life.
Janko Nikolich-Zugich of the Oregon Health and Science University in Beaverton, Ore., and his colleagues suspected that the immune system plays an important role. They worked with two groups of rhesus macaques. Starting just after puberty, monkeys in one of the groups were fed about a third fewer calories than were monkeys in the other group. When the monkeys were between 19 and 23 years old, the researchers monitored differences in immune function between the groups for 42 months.