Fasting does not prolong life
Vladimir Gram, "Newspaper.Ru»
Half a century ago, it was strictly shown that limiting calorie intake significantly prolongs the life of worms, fruit flies and even rodents. And many followers of low-calorie diets have appeared among people hoping to achieve longevity in this way.
As it turns out, these hopes may be in vain. Comparing the production of one of the substances associated with the prolongation of life in the organisms of mice and humans, scientists for the first time found cardinal differences. Calorie restriction may not be that important. But limiting protein intake may be important.
Previous molecular studies have shown that in most model animals, intracellular reactions involving the so-called insulin-like growth factor-1 (IGF-1) were involved in prolonging life. Although the true mechanism remains a mystery behind seven seals, it is known that several proteins are involved in these reactions, which play a key role in the development of various tumors – for example, those controlled by the famous p53. And the growth factor itself, in a sense, is supposed to play a role in regulating cancer.
Calorie restriction in rodents significantly reduces the production of IGF-1, which is synthesized, for the most part, in the liver.
However, as Luigi Fontana and his colleagues from the Higher Institute of Health in Rome, Italy, and George Washington University in St. Louis, USA, have shown, a low-calorie diet does not have such an effect on people. The corresponding work was published in the journal Aging Cell.
Members of the Society for Calorie Restriction with Optimal Nutrition (CRON), or kroni, as they call themselves, helped to discern the difference. And of course, the control group of people who ate standard.
"We have been following a cohort of kroni on a low–calorie diet for several years (on average, by the time of the analysis, they had been following it for about seven years)," Fontana says. "And we didn't notice any difference in IGF–1 levels compared to the control group."
To figure out what's the matter, scientists even recruited another fifty volunteers, and for a whole year tormented some of them with a diet with a 25% reduced calorie content, and some with enhanced exercises, which, on the contrary, forced the body to burn 25% more calories despite the fact that they ate as before. And again – there was no effect from the diet.
The scientists were rather puzzled by the fact that the results of the study on rodents and humans did not coincide, admits Luigi Fontana, and decided to find out whether the second factor – protein consumption - was involved in these reactions. It is known that it also independently affects the level of IGF-1.
As it turned out, adherents of a radically vegetarian diet who do not recognize any animal products (vegans) had significantly lower IGF-1 levels.
Vegans, whom scientists have also been following for several years, get about 10% of energy from proteins, and those on a low–calorie diet - about 25%. At the same time, starving people consciously increase their protein intake, since this is almost the only way to ensure the supply of sufficient amounts of essential nutrients with reduced energy consumption.
It was not easy to convince them to give up proteins as well, but six people still succumbed to Fontana's persuasions. "And after three weeks, the level of insulin-like growth factor–1 circulating in their body decreased significantly," the researcher rejoices.
Previous studies have already shown that diets with a low protein content can reduce the likelihood of developing certain types of cancer, but their conclusions cannot be called final. In addition, the molecular mechanisms of such influence are unknown.
Fontana does not offer a radical rejection of proteins with a transition to fats and sugar. According to him, it will be enough if people simply follow the current recommendations of doctors – to consume 0.7-0.8 grams of protein per day per kilogram of their weight. Most residents of developed countries are significantly overdoing it here.
Portal "Eternal youth" www.vechnayamolodost.ru25.12.2008