Extra calories are bad for the kidneys
Scientists from Moscow State University named a new plus of a low-calorie diet
Limiting the number of calories not only improves the health of the heart and blood vessels, but also significantly reduces the chances of developing severe kidney problems. This conclusion was reached by Russian biologists who published an article in the journal Cells (Andrianova et al., Mechanisms of Age-Dependent Loss of Dietary Restriction Protective Effects in Acute Kidney Injury).
"Our experiments have pointed to the important role of autophagy in protecting the kidney. The main task of this process is the disposal of damaged components in cells. It works worse in older animals, which leads to the accumulation of poorly functioning molecules and organelles. This may be the reason that cutting the caloric content of the diet almost does not help them," says Egor Plotnikov from Lomonosov Moscow State University.
Experiments conducted on worms, mice and other animals back in the 1960s showed that limiting the calorie content of the diet significantly prolongs the life of animals. Over the following decades, biologists have identified dozens of genes and hormones potentially involved in this phenomenon, but none of them have been able to learn how to use to prolong the life of these animals and humans.
On the other hand, observations of the health of people who consume small amounts of food suggest that a low-calorie diet protects them from the development of strokes, diabetes, hypertension, atherosclerosis and other problems related to the work of the heart and blood vessels.
According to the press service of Moscow State University, Plotnikov and his colleagues discovered another positive consequence of calorie restriction by observing what was happening in the kidneys of young and elderly rats whose blood supply was periodically disrupted artificially.
Recently, Plotnikov's team found out that the kidneys of elderly rats cope much worse with such emergencies due to the fact that autophagy is disrupted in their cells - the process of assembling and destroying improperly folded proteins and damaged mitochondria (the main "power stations" of the cell). An excess of this garbage in the kidneys of elderly people leads to mass cell death and serious complications with interruptions in blood supply.
At the same time, a chronic lack of calories enhances and accelerates autophagy, forcing the cell to process garbage more actively and reuse its components in its vital activity. This idea prompted Russian biologists to think that such a diet can help the kidneys to protect themselves from the consequences of stopping blood flow.
Experiments have shown that calorie restriction significantly improved the kidneys of young rats after temporarily disconnecting them from the circulatory system – recovery accelerated by about two to three times. The more modest the diet, the stronger the effect was: rats whose diet was cut by about a third recovered twice as fast as those whose caloric intake was limited by 25%.
What is interesting: this effect was not always manifested. The kidneys of rats began to behave this way only if the animals had been eating this way for more than a month, and also if they themselves were young enough. Why this is so, scientists plan to find out in subsequent experiments.
"This suggests that the protective pathways of old organisms do not work quite correctly and further research is required to improve the existing methodology. Perhaps the old body needs a longer period of restriction of nutrition in order for the positive effects to manifest themselves in full," concludes Plotnikov.
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