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It’s an old saying that what doesn’t kill you makes you stronger, but current thinking among researchers is that this may have a sound basis in science. The theory is that things which temporarily stress the body make it stronger and healthier in the long run. It is a process called hormesis, or the biological effects of low level exposure.
The idea is that some substances we encounter, or things which happen to the body act as stressors and trigger the body’s own repair mechanisms. As well as repairing the damage caused by the stressor, any other minor damage, which had not been enough on its own to trigger repair mechanism, is put right.
Not a new observation
Hugo Schulz, a German pharmacologist (drug specialist) is credited with being one of the first people to draw attention to this phenomenon – as long ago as 1888. He found that yeasts could be stimulated to grow by administering poisons to them in low doses.
But his observations were used by some to explain homeopathy, where very dilute concentrations of substances are used to cure the very symptoms they cause when given in greater quantities. There are as many people against homeopathy as for it, and because of its temporary association with homeopathy, hormesis too became an unpopular theory.
Resurgence of interest
But in the 1940s interest in the phenomenon was rekindled by scientists working on a natural antibiotic produced by cedar wood to destroy a fungus that lived off it.
They named the phenomenon ‘hormesis’ meaning ‘excite’ in Greek.
Since then the scientist Edward Calabrese, Professor of Toxicology at the University of Massachusetts' School of Public Health in Amherst, MA, USA has written extensively on the subject claiming that it impacts on many areas of life – from risk assessment of environmental toxins to determination of therapeutic doses of medicines. He first observed hormesis when testing a plant inhibitor on peppermint plants. He found that when accidentally diluted too much, the weed-killer actually stimulated growth of the plants.
And he is right about medicines too as it is well-known that antibiotics kill bacteria at certain concentrations, but can encourage the same organisms to grow, when present at much lower levels.
Dioxins as an example of hormesis
Many people will tell you that dioxins are toxic by-products of manufacturing processes, and injurious to health. But when given in low doses to rats, they have been shown to prevent the animals developing cancer.
Speaking of rats, substances which in high doses have caused cancer in these animals are present in a variety of fruit and vegetables, including apples, oranges, bananas, cabbage, broccoli, Brussels sprouts and mushrooms. But present in very small quantities.