UW primate research links caloric intake and aging

Two rhesus monkeys from the 2009 student in which one was served a restricted diet and the other could eat as much as it liked The 27-year old and 29-year old monkeys have since died of natural causes. 

Image By: Jeff Miller

The use of non-human primates in research has fueled some of the most pivotal scientific discoveries to date and saved countless lives. Rhesus macaques have been instrumental in the development of vaccines, the discovery of HIV/AIDS treatments, the characterization of blood groups, and a myriad of other medical and scientific breakthroughs.

In the 1980s, both the National Institute of Aging and the Wisconsin National Primate Research Center began studies meant to probe the biological mystery of aging. As rhesus macaques share similar biology and physiological signs of aging with humans, they were chosen as research subjects by both groups.

In 2009, the UW-Madison group published their results and concluded that calorie restriction slows the ageing process and staves off illnesses such as cardiovascular disease, insulin resistance, and even cancer. Further, they found that calorie restriction increases overall survivability.

However, a parallel study conducted by the NIA found something different. In fact, they found very little measurable benefit to calorie restriction as it pertains to aging. Conflicting results in science can be awkward at best, as research teams compete for funding from similar sources. In some cases, conflicting results can even imply falsified data.

However, in a remarkable display of collaborative spirit, the scientists behind each study cross analyzed the data in an attempt to explain the apparent dissonance. As a result of their cooperation, humanity is a little closer to understanding the biology of aging.

In their report, published recently in Nature Communications, the scientists remark that one major difference between the studies was the allotment of the food in the calorie rich groups and the onset of calorie restriction. Notably, the WNPRC study only initiated calorie restriction after monkeys had attained adult stature.

Further, marked genetic differences existed in the monkeys between the two studies, as well as large differences between diets. Interestingly, the NIA study, which fed their monkeys a lower fat, protein and fiber rich diet (compared to the WNPRC diet), found less of an impact of calorie restriction on aging.

“Data from both study locations suggest that the [calorie restriction] paradigm is effective in delaying the effects of aging in nonhuman primates but that the age of onset is an important factor in determining the extent to which beneficial effects of [calorie restriction] might be induced,” Ricki Colman, a senior scientist of the WNPRC, commented on the data from the collaborative effort.

“Unfortunately I don’t think [collaborative science] actually happens that often and not to the extent that we collaborate with NIA,” Colman added.

While it is a rare event, this instance of teamwork not only shed light on a complex scientific phenomenon but also salvaged a large sum of money. Long term primate research is an expensive endeavor, and by working together, the NIA and WNPRC groups made sure they got the most out of the data they worked so hard to obtain.

When asked what mechanisms were behind the effect of calorie restriction on aging, Colman explained that she believes there is more to learn.

“There are likely multiple mechanisms at work and ... they will include alterations in energy metabolism and systemic inflammation,” Colman said. 

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