In a similar study of young rhesus monkeys (7-14 years old) at the Wisconsin National Primate Research Center, researchers found a trend towards longer lifespans for calorie restricted animals after they had discounted what they felt were not age-related deaths. This has led some experts in the field to suspect that the deaths in the restricted group may have been related to the treatment (roughly half of the total deaths were eliminated from their calculations) especially since there were a higher number of deaths that were termed non-age related in the calorie restricted group than the controls.
Another difference between the studies was diet composition with more sucrose included in the Wisconsin trial, which may be related to the higher incidence of diabetes in the control animals in that study as compared to the NIA study. An article by aging expert Dr. Austad suspected that the differences may be attributed to the type of calorie (fat, sugars, proteins) ingested as opposed to the quantity.
So much for finding the fountain of youth in dieting. This primate is going to enjoy some ice cream with fudge now…and sprinkles.
Austad SN. Ageing: Mixed results for dieting monkeys. Nature, August 29, 2012.
Maxmen A. Calorie restriction falters in the long run: Genetics and healthy diets matter more for longevity. Nature, August 29, 2012.
Mattison JA, Roth GS, Beasley TM, Tilmont EM, Handy AM, Herbert RL, Longo DL, Allison DB, Young JE, Bryant M, Barnard D, Ward WF, Qi W, Ingram DK, de Cabo R. Impact of caloric restriction on health and survival in rhesus monkeys from the NIA study. Nature. August 29, 2012. doi:10.1038/nature11432