The cells of our body are frequently exposed to hazards that can cause them to be damaged, malfunction or die. Yet they have defence systems that can sometimes be strengthened by small doses of stress, a phenomenon known as hormesis. Scientists are investigating whether food compounds and medicines can harness these protective processes to benefit health.

The hazards of modern life are often discussed in terms of their potential to damage major organs. For example, air pollution can damage the lungs and contribute to asthma and other breathing disorders.

Although effects at the organ level are important, this view can miss the challenges faced by the individual cells that make up the lungs and every other part of the body. Our cells are frequently exposed to stresses including ultraviolet radiation from the sun, alcohol, pollutants and the byproducts of some medicines.

These hazards can damage DNA, which carries a cell’s genetic instructions, as well as proteins and the fatty membranes surrounding cells. If the damage becomes severe enough, it can cause cells to malfunction or die. Yet, despite this seemingly constant barrage of potential stresses, most of our cells adapt, survive and function effectively throughout our lives.

Our cells possess specialised stress responses that detect particular hazards and alter the activity of genes involved in protecting the cell. One of the best-studied examples is........

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