Can starvation in life prolong life?

In rhesus monkeys, dieting could not prolong life

30.08.2012

For centuries, scientists have been dealing with the myth of eternal youth and immortality. A few years ago, the first step was taken in this direction. Researchers extended the lives of mice, worms, fish and flies by reducing caloric intake in the laboratory. In 2008, the maximum age of baker's yeast, which had been genetically modified, was even tenfold extended. However, recent studies on rhesus monkeys have shown that this effect is not effective in primates. Whether a diet can also prolong a person's life becomes more and more dubious. Nevertheless, the calorie reduction in the elderly, especially in the US finds more and more followers.

In rhesus monkeys starvation in old age did not prolong life
The idea of ​​extending people's lives by years, or even making them immortal, is both fascinating and frightening. Current research results of the „National Institute on Aging (NIA)“ in Maryland, however, this scenario is a long way off. While a reduced calorie intake in mice, worms, fish, and flies has been shown to prolong the animals' lives, the rhesus monkey diet does not appear to work in this regard.

Scientists have been putting rhesus monkeys on the diet for 23 years. They consumed 10 to 40 percent less calories per day than is included in the usual food of the animals. Like Julie Mattison and her team in the magazine's online magazine „Nature“ However, there was no life-prolonging effect compared to the normal-fed control group. The researchers were nevertheless able to observe an effect of the diet on the metabolism of animals, which received fewer calories until they reached the age of 16 to 23 years. The metabolic activity was healthier. Rhesus monkeys become on average 27 years old in captivity. Only in exceptional cases, they reach the age of 40. The animals, which had already begun very early with the diet, suffered only later under the usual age illnesses, since their immune cells functioned better. Another observation of the scientists concerned the male monkeys. These showed maturity delays and slowed bone growth in response to the diet. Finally, the researchers came to the conclusion that fewer calories in Rhesus monkeys do not lead to a longer life.

„To think that simply reducing calories can make such a far-reaching change was remarkable“, says gerontologist Don Ingram of Louisiana State University at Baton Rouge in „Nature“, who designed the study 30 years ago while at the NIA.

Life-prolonging effect seems to depend on the reduced diet
The results of the NIA researchers are in direct contrast to previous study results from the National Primate Research Center in Wisconsin (WNPRC). There are also long-term studies on a possible life-prolonging effect of calorie reduction instead. WNPRC scientists concluded that the reduced caloric intake prolongs the life expectancy of rhesus monkeys. While in the control group of normal-fed animals of 76 monkeys 14 died from age-related diseases, there were only five in the diet group. In the NIA study, 24 percent of the animals and 20 percent of the diet group died in the control group. The mortality rate was therefore approximately the same in both groups.

Difference lies in the type of diet
As a cause for the contrasting study results, the NIA researchers suspect the strongly divergent diet of rhesus monkeys. In the WNPRC, monkeys of the diet group were healthier compared to the control group as they were given unhealthy diets and the diet group ate less of them. In the NIA, however, the monkeys were fed on a natural basis. For example, the animals in the WNPRC received feed consisting of 28.5 percent granulated sugar, while the NIA diet contained only 3.9 percent. Granulated sugar is considered to be beneficial for the development of type II diabetes, a common cause of death in advanced age. In addition, the pet food of the NIA, in contrast to the diet of WNPRC also included fish oil and antioxidants. The monkeys of the control group in the WNPRC were also allowed to eat as much as they wanted. Accordingly, their weight was higher than that of monkeys in the NIA, who received a fixed amount of food. Rick Weindruch, gerontologist at WNPRC and study leader, concedes „Nature“ on: „All in all, our food was probably not that healthy.”

„Overall, the WNPRC results may have reflected an unhealthy control group rather than a long-lived diet group“, the researchers write. „When we started this study, the dogma was that a calorie is a calorie, "explains Ingram „Nature“. „I think it's clear that the type of calories the monkeys ate made a big difference. "(Ag)

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Picture: Rainer Sturm