Nutrition – Eating less prolongs life

Most people would like to live longer. A healthy lifestyle is said to help. So let’s stay fit, eat and drink less and quit smoking. But do people stay alive longer when they eat fewer calories? Laboratory experiments have shown this to be the case with flies, worms and mice. Yale University has now been able to prove that a moderate diet can also give homo sapiens health and therefore a few years.

The data analysis published in the journal “Science” is based on a long-term study of the effects of reduced calorie intake in healthy adults. As part of the “comprehensive evaluation of the long-term effects of reduced energy (calorie) intake”, the baseline caloric intake of 200 study participants was determined and some of the subjects were invited to eat 14% fewer calories. Over a period of two years, the researchers analyzed the health effects of the two groups.

“We wanted to find out how calorie restriction is as good for humans as it is for animals, and what caused it,” said study author Vishwa Deep Dixit, a professor of pathology and immunobiology, in a statement from Yale University in New Haven. , Connecticut.

It was known that chronic inflammation can trigger life-shortening chronic diseases. To find out if a moderate diet counteracts inflammatory processes, Dixit and his team looked at its effects on the immune system and metabolism. We started with the thymus, also called sweetbread. T cells, among other things, mature in this gland above the heart. These are blood cells that act as memory cells for the immune system and destroy diseased cells. The thymus ages faster than other organs. According to Dixit, at the age of 40, he is already 70% obese and dysfunctional. Fewer T cells are formed. Older people are at greater risk of serious illnesses.

The thymus can rejuvenate

Using magnetic resonance imaging, the researchers were able to see that the thymus glands of the subjects who followed a low-calorie diet were less fatty and functioned better than those who continued to eat normally during the study period. Those on a moderate diet had more T cells at the end of the study than at the start. “The thymus can rejuvenate,” says Dixit. However, he and his team found no changes in the product of the gland: the genetic information in the T cells was expressed identically to before the study. Thus, rejuvenation of the thymus had to be explained elsewhere. “It turns out that the developments took place in the microenvironment of this tissue,” says Dixit.

At the same time, the researchers examined the body fat of the dieting subjects at the start, middle and end of the study period. Fat cells also contain immune cells. If these sentinels are activated uncontrollably, they can trigger inflammatory processes. “We found remarkable changes in gene expression in adipose tissue,” explains Dixit. Some of these genes have been shown to promote longevity, reduce inflammation, and support metabolism in animals.

The researchers focused on a gene called acetylhydrolase, or PLA2G7 – a protein made by macrophages in the immune system. To understand what causes the changes in PLA2G7 gene expression in diet participants, the researchers also followed the process in mice. “Less PLA2G7 has similar benefits for animals that calorie restriction has for humans,” says lead author Olga Spadaro.

The mice’s thymus glands remained functional longer and the animals did not suffer from age-related inflammation. Thus, protein is the driving force for improving immune function, reducing inflammation, and possibly extending a healthy lifespan. “There are discussions about the best diet. But even fewer calories have an effect on biology, which could extend our lives,” says Dixit.

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