Caloric restriction without malnutrition increases longevity and delays age-associated disorders in different species. The value of caloric restriction as a tool to understand human aging relies on translatability of its effects in primates. Results from a 25-year study of diet and aging in monkeys at the University of Wisconsin-Madison show a significant improvement of age-related and all-cause survival in monkeys on a long-term ~30% restricted diet since young adulthood.
Restricting the intake of calories while continuing to supply essential nutrients extends the lifespan by as much as 40 percent. "We study caloric restriction because it has such a robust effect on aging and the incidence and timing of age related disease," says corresponding author Rozalyn Anderson, an assistant professor of geriatrics. "Already, people are studying drugs that affect the mechanisms that are active in caloric restriction."
Many of the benefits of caloric restriction are linked to regulation of energy, Anderson says. "It affects how fuel is utilized. Caloric restriction essentially causes a reprogramming of the metabolism. In all species where it has been shown to delay aging and the diseases of aging, it affects the regulation of energy and the ability of cells and the organism to respond to changes in the environment as they age."
Chief among the metabolic deficits is diabetes, which can be seen as "an inability to properly respond to nutrients," Anderson says. Diabetes damages fat, muscles, blood vessels and even brain functioning, and the growing epidemic of diabetes is a leading cause of death and disability in the United States.
Caloric restriction studies encompass two central issues of relevance to human health, first the relationship between chronological age and increased disease incidence, and second how nutritional inputs can modulate aging.