"Eat modestly and live longer" seems to be the message from a new study that tracked the food habits and linkages of rhesus monkeys with regard to their healthy life and longevity.
In the collaborative study, teams from the University of Wisconsin-Madison and National Institute on Aging worked together to resolve the controversial aspect of aging research.
The joint effort came after the two groups had a varied conclusion on the same topic in the past. In the new study, the competing groups showed that the less the monkeys ate, the more they lived.
The main takeaway from the study was the importance of caloric restriction in bringing about positive consequences on aging and health. At the same time, it noted that in primates like monkeys, other factors like age, diet and sex also matter in optimizing the benefits of lower caloric intake.
The study is published in the journal Nature Communications.
Not A Recipe For Lifestyle
Commenting on the findings of the study, one of the authors clarified that cutting food is not a life style recommendation.
"It's a research tool, not a lifestyle recommendation. We are not studying it so people can go out and do it, but to delve into the underlying causes of age-related disease susceptibility," said Rozalyn Anderson, an assistant professor who was part of the study.
The underlying cause is only looking at how a restricted diet alters the metabolism and energy in the body.
The UW-Madison has been engaged in the study for more than two decades to trace the links between food calories and aging-related disease susceptibilities. The university had been keeping a group of rhesus monkeys under observation in which half of them were allowed to eat whatever they want.
In the other group, restrictions were clamped and the animals were fed nutritious food but calories were slashed by almost 30 percent compared with the other group.
The new report has come out 25 years after the study started and found that monkeys on unrestricted diets posed three times greater risk of age-related death and diseases than those on regulated calories.
Over the years, many monkeys died and the scientists documented how each one of them died and their food patterns.
Out of the 38 monkeys that died, 28 were from the unrestricted diet on age-related causes compared with just 10 from the restricted group. The diseases ranged from cardiovascular, diabetes, cancer, brain atrophy, sarcopenia and bone loss.
Competing Claims Balanced
The UW-Madison study in 2009 reported tangible benefits in survival and reductions in cancer and other disorders for monkeys that ate frugally, compared with their gluttonous peers.
However, the NIA study in 2012 took a different stand and noted there was no significant improvement in survival from restricted intake though a trend toward improved health could be noticed.
Commenting on the erstwhile polarized views, one of the corresponding authors said the variation was the result of not touching other variables that impinged on aging and calorie-related discourse on primates. In the new study, those areas have been touched.
"These conflicting outcomes had cast a shadow of doubt on the translatability of the caloric restriction paradigm as a means to understand aging and what creates age-related disease vulnerability," said Anderson, one of the corresponding authors.
While working together, the teams analyzed data from many years including those of 200 monkeys from both studies.
The broad analysis convinced the scientists the reason why the studies had different results. The role of caloric restriction in aging and disease was unmistakable. Yet, the effects of the same on primates also depended on factors like diet, age and sex.
Impact On Humans
The findings of the study on rhesus monkeys also have a bearing on the long debate on caloric restriction and its spillover on humans.
In the 1930s, tests on lab rats showed that longer lives and a decrease in disease are rooted in a few calories. Those findings were further buttressed by studies on worms, yeast, flies and mice showing the potential for longer life expectancy with regulated food practices.