Calorie restriction (CR), a reduction of 10–40% in intake of a nutritious diet, is often reported as the most robust non-genetic mechanism to extend lifespan and healthspan. CR is frequently used as a tool to understand mechanisms behind ageing and age-associated diseases. In addition to and independently of increasing lifespan, CR has been reported to delay or prevent the occurrence of many chronic diseases in a variety of animals. Beneficial effects of CR on outcomes such as immune function, motor coordination and resistance to sarcopenia in rhesus monkeys have recently been reported. We report here that a CR regimen implemented in young and older age rhesus monkeys at the National Institute on Aging (NIA) has not improved survival outcomes.
—Impact of caloric restriction on health and survival in rhesus monkeys: the NIA study
The NIA study ran for 20 years on two groups of monkeys, “early onset” monkeys who started CR (or being in the control) at a young age and “late onset” who were older. As you’d expect, there were more age-related deaths in the “late onset” group (80 out of 90 monkeys) than the “early onset” (19 out of 90).
By contrast the WNPRC study found that CR did have a positive effect on lifespan:
Caloric restriction (CR) without malnutrition delays aging and extends lifespan in diverse species; however, its effect on resistance to illness and mortality in primates is not clearly established. We report findings of a 20-year longitudinal adult-onset CR study in rhesus monkeys aimed at filling this critical gap in aging research. In a population of rhesus macaques maintained at the Wisconsin National Primate Research Center, moderate CR lowered the incidence of aging-related deaths. At the time point reported 50% of control fed animals survived compared with 80% survival of CR animals.
—Caloric restriction delays disease onset and mortality in rhesus monkeys
The WNPRC study had 76 monkeys, 19 of which died from age-related causes.
There’s a long discussion section at the end of the NIA article talking about differences between the two studies.
At the time point reported 50% of control fed animals survived compared with 80% survival of CR animals
That line from the abstract is an outright lie. Check out the graphs. The actual survival rate was something like 50% vs 60%. CR won, but it was not statistically significant. What this really showed was a trade-off between “age-related mortality” and frailty, although the latter is usually considered “age-related” in humans.
The NIA rhesus monkey study found:
The NIA study ran for 20 years on two groups of monkeys, “early onset” monkeys who started CR (or being in the control) at a young age and “late onset” who were older. As you’d expect, there were more age-related deaths in the “late onset” group (80 out of 90 monkeys) than the “early onset” (19 out of 90).
By contrast the WNPRC study found that CR did have a positive effect on lifespan:
The WNPRC study had 76 monkeys, 19 of which died from age-related causes.
There’s a long discussion section at the end of the NIA article talking about differences between the two studies.
That line from the abstract is an outright lie. Check out the graphs. The actual survival rate was something like 50% vs 60%. CR won, but it was not statistically significant. What this really showed was a trade-off between “age-related mortality” and frailty, although the latter is usually considered “age-related” in humans.