They try to clear up the conflicting results from the NIA and UW studies. Both studies have some flaws, but it seems clear that calorie intake does have a significant impact on health and survival. Although, one could wish that the results were more clearer, because to me, it doesn't absolutely settle the issue. There were some issues in both studies; as well as inconsistencies with how the monkeys responded to CR. Many things may have compromised the studies' results, some of which they talk about in the paper.
So, that being said, CR is a gamble... we're still no closer to knowing how much CR will work in humans, if at all (I mean beyond a healthy diet). CR's effects can be very different even among different strains of mice. Interesting results from the young onset monkeys though! It seemed to be harmful...
I've no further comment right now, but hopefully some of you can chime in!
I've written on the studies before here if you want to check it out.
Abstract
Caloric restriction (CR) without malnutrition extends lifespan and delays the onset of age-related disorders in most species but its impact in nonhuman primates has been controversial. In the late 1980s two parallel studies were initiated to determine the effect of CR in rhesus monkeys. The University of Wisconsin study reported a significant positive impact of CR on survival, but the National Institute on Aging study detected no significant survival effect. Here we present a direct comparison of longitudinal data from both studies including survival, bodyweight, food intake, fasting glucose levels and age-related morbidity. We describe differences in study design that could contribute to differences in outcomes, and we report species specificity in the impact of CR in terms of optimal onset and diet. Taken together these data confirm that health benefits of CR are conserved in monkeys and suggest that CR mechanisms are likely translatable to human health.
"All males and females from the NIA old-onset groups consumed fewer calories than their counterpart controls from UW, instead both control and CR were closely aligned with food intake values of UW CR. Importantly, the median survival estimates for old-onset males were very high, similar to what has been reported previously as the 90th percentile for this species (∼35 years of age). Six of the original 20 monkeys have lived beyond 40 years of age, the previous maximal lifespan recorded, and one old-onset CR male monkey is currently 43 years old, which is a longevity record for this species. Median survival estimates for old-onset females, ∼27 and ∼28 for controls and CR respectively, were also greater than national median lifespan estimates, with one remaining female currently 38 years of age. The clear benefit in survival estimates for monkeys within the old-onset cohort compared to UW controls suggests that food intake can and does influence survival. The lack of difference between control and CR old-onset monkeys suggests that a reduction in food intake beyond that of the controls brings no further advantage."
http://www.nature.co...les/ncomms14063
