There are physiological processes in which the body becomes "stronger" by having certain stimuli that we might think are harmful, but in a low dose they can greatly improve the body's adaptability and resistance.

This response is known as hormesis.

A clear example is physical exercise, generating "damage" in muscle fibers; these must be "repaired" and this makes the muscle grow and present greater adaptation to future stress (we can do more strength or run more if we have this previous hormetic dose).

There are a large number of hormetic agents, including exercise, dietary restriction, radiation, heat, cold, heavy metals, antibiotics, ethanol, pro-oxidant agents.

When mammalian cells, including human cells, are exposed to low doses of oxidizing agents, in as little as nine hours the expression of protective genes increases, allowing “adapted” or “hormetically conditioned” cells to be significantly more resistant to a subsequent oxidative stress, even fifteen or thirty hours after the stimulus.

For all of the above, hormesis has emerged as an important manipulation to delay aging, but, despite the fact that multiple combinations of hormetic stressors have been studied in different animal models, the mechanism of hormesis during aging has not been fully explained.

For example, in studies on the hormetic effect on aging, it was found that D. melanogaster flies subjected to thermal stress had a better response to higher doses of stress in adult life.

Interestingly, and associated with this protection, an increase in the production of the heat stress response protein HSP7041 was found.

“The Human Being needs difficulties; are necessary for health. Carl Jung