Hormesis is a term used by toxicologists to refer to a biphasic dose response to an environmental agent characterized by a low dose stimulation or beneficial effect and a high dose inhibitory or toxic effect. In the fields of biology and medicine hormesis is defined as an adaptive response of cells and organisms to a moderate (usually intermittent) stress. — Ageing Research Reviews,
Hormesis refers to a beneficial biological response to mild and intermittent stressors that would be damaging in high doses particularly over sustained periods of time (chronic). The term is derived from toxicology. It came into use when it was discovered that low doses of toxins could be beneficial to certain organisms. The key to hormesis is keeping the dose within the hormetic zone , which elicits a favorable biological response.
Some examples of hormetic stressors include:
- Caloric restriction or fasting e.g. to promote autophagy and cellular repair, reset the metabolism
- Cold or heat exposure (e.g. sauna) to improve cardiovascular health
- Exercise to build strength and endurance
- Nutritional hormesis from plant substances (e.g. phytochemicals )
Applying hormesis in aging research and therapy is based on the principle of stimulation of maintenance and repair pathways by repeated exposure to mild stress. — Suresh Rattan SR Suresh Rattan , Human & Experimental Toxicology
The research on hormesis as a preventative mechanism in the context of aging is emerging and not yet conclusive, but few people would challenge the benefits of physical activity for health and longevity. Other hormetic stressors such as phytochemicals (flavonoids, polyphenol, resveratrol etc.) are more controversial .