A low-calorie diet still prolongs the life of monkeys
The outstanding collaboration between two competing research groups – from the University of Wisconsin at Madison and the US National Study of Aging – was their first joint work aimed at resolving one of the most controversial stories in the field of aging studies.
A photo taken in 2009 of macaques involved in a University of Wisconsin-Madison study. On the left is a 27-year–old monkey kept on a low-calorie diet, and on the right is a 29-year-old monkey who consumed unlimited amounts of food. Subsequently, both animals died of natural causes.
In 2009, researchers from the University of Wisconsin at Madison in experiments on rhesus monkeys demonstrated a pronounced positive effect of a low-calorie diet on survival, as well as a reduction in the risk of cancer, cardiovascular disease and insulin resistance. However, the results of the work carried out in 2012 by scientists of the US National Institute for the Study of Aging partially refuted this conclusion, since the authors failed to register a significant improvement in survival, but they revealed a certain trend towards improving health.
These contradictory data have called into question the applicability of the low-calorie diet paradigm for deepening knowledge about aging and age-related predisposition to diseases. In order to resolve this issue, competing laboratories joined forces and analyzed observations collected over many years, including data for almost 200 monkeys involved in both studies. To date, they believe that they know the factors that caused the research to bring contradictory results.
Firstly, the age of the animals at the time of caloric restriction of the diet was different for the two studies. Comparative analysis has shown that eating less food has a positive effect on the health of adults and elderly animals, but is not useful for young individuals. This is a significant difference from the results of studies on rodents, in which the effects of a low-calorie diet were more pronounced with a decrease in the caloric content of the diet at an earlier age.
Secondly, in a study by the US National Institute for the Study of Aging with a later transition to a low-calorie diet, control group animals ate less food compared to control group monkeys at the University of Wisconsin. This was associated with increased survival of the control group in the first case. This observation means that even small differences in the amount of food consumed by primates can have a significant impact on the aging process and health status.
Thirdly, the composition of the diet of monkeys was very different for the two studies. At the National Institute for the Study of Aging, the animals ate natural foods, and at the University of Wisconsin – processed foods with a high sugar content. The animals of the University of Wisconsin control group were more well-fed than the animals of the control group in the second study. This indicates that with unlimited access to food, its quality has a great influence on the composition of the body and the amount of adipose tissue.
Finally, the researchers identified key sex differences for the relationship between diet, amount of adipose tissue and insulin sensitivity. In general, they concluded that females are less susceptible to the negative effects of obesity than males. This previously unknown pattern is especially important for primates and is likely to extend to humans.
As a result of the analysis, they came to the conclusion that a low-calorie diet really allows you to change the nature of aging. However, in the case of primates, factors such as age, diet, and gender should be taken into account to determine the full range of positive effects of reducing caloric intake.
Article by Julie A. Mattison et al. Caloric restriction improves health and survival of rhesus monkeys is published in the journal Nature Communications.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of the University of Wisconsin-Madison: Calorie restriction lets monkeys live long and prosper.
18.01.2017