Cardiac muscle cells that have experienced short-term oxygen deprivation become more “trained” – this increases their chances of surviving a new encounter with hypoxia. Specialists from the Manchester Institute studied this mechanism on the example of cardiomyocytes of caiman turtles. They go through oxygen starvation in the embryonic stage, and then in adulthood turn out to be resistant to repeated exposure to hypoxia: they become more sensitive to calcium levels, block aggressive forms of oxygen and so on. Researchers are implementing this mechanism, which is an example of hormesis, in cardiology, increasing the resistance of heart cells to hypoxia in patients with a tendency to heart attacks. Another example of the implementation of hormesis mechanisms is the healing effect of short-term fasting. Thus, scientists from the University of Southern California found that mice regularly fasting for two to four days undergo immune system renewal. The stressed organism seeks to optimise its resources: it “eats” aged immune cells, while stimulating the formation of young and full-fledged cells. Other studies have shown that short-term fasting reduces the risk of Alzheimer’s disease, rejuvenates aged stem cells, and activates genes responsible for longevity. Studying the mechanisms of hormesis is important for combating age-related disorders in the body. For example, excessive exposure to stress changes the permeability of cell membranes, leading to cell death, while hormetic, dosed stress activates “cleaning” processes inside the cell, contributing to the destruction of defective and inefficient organelles, such as mitochondria. This helps cells stay young longer and perform their function better.

Hormetins – moderately stressful factors that promote activation of adaptation mechanisms – are divided into several groups:

• Physical. They include sports loads, action of moderately high or low temperatures (bath, sauna, cryosauna). This group also includes radiation hormesis, which implies a positive effect on cells of small doses of radiation, close to the value of the natural radioactive background of the Earth – it has been proven that this stimulates the immune system;
• Food or nutritional hormetins. They are contained in food products and in small doses activate the processes of cell renewal and cellular structures, and in large doses have a damaging effect. Food hormetins include quercetin, found in apples, plums, cranberries, cherries, onions, currants; resveratrol, rich in red wine and peanuts; curcumin, found in curry; carnosine in chicken and turkey and others.
• Mental hormetins. These include stress, which a person encounters in the process of learning new information, reading complex books, solving problems, participating in intellectual games and so on.