[Trace elements and their physiological roles].

Of 95 naturally occurring elements of the periodic table, no less than 25 perform essential functions in the human body. Eight of these, namely zinc, copper, selenium, cobalt, chromium, molybdenum, manganese and iodine, are required in small amounts and each comprises less than 0.01% of the body weight and termed essential trace elements. In the body, they function in a similar way; most of them are at the active site of enzymes or of physiologically active substances of the body. Dietary deficiency causes a variety of clinical features, which are consistent with the decreased activity of these active substances. Recent topics are the resemblance of these features and their background pathophysiology with those of aging.