Hormesis and health: A little of what you fancy may be good for you

The term hormesis refers to beneficial effects from low doses of potentiall y harmful substances. Although there are many laboratory examples of this p henomenon, it remains controversial and has never become widely accepted by the health community. This review goes beyond the laboratory and describes many clinical and common sense, real-world examples of hormesis that often go unrecognized. Many vitamins and minerals are essential for life at low doses but toxic at higher ones. Similarly, exercise, caloric restriction, a nd alcohol consumption are examples of processes that are harmful in the ex treme but beneficial in moderation. This review also highlights possible re asons why acceptance of the hermetic paradigm has lagged. These include hig h-dose toxicologic testing that precludes the demonstration of low-level ef fects and the threat posed by hormesis to the currently accepted precaution ary principle, which assumes that any dose of a chemical is potentially har mful.