Trace elements in nutrition.

Advances in trace element research over the last decade have done much to elucidate the function of these nutrients at the biochemical level. Five new trace elements have been identified and the general relevance of microelements in human nutrition has undergone reassessment. Deficiencies of iodine, iron and fluorine remain important problems and necessitate supplementation. Suboptimal nutrition in chromium, copper, selenium, zinc and possibly vanadium has been suggested, and these elements are generally acknowledged to be of concern in human nutrition. Genetic factors and other "conditioning" agents have been implicated in the aetiology of a number of trace element deficiencies in apparently well nourished communities. Tissues under anabolic stress have been recognized to be especially sensitive to trace element deficits, and the particular vulnerability of the fetus has been demonstrated on a number of occasions. In practical dietary terms, the loss of microelements during the refining and processing of food has been widely illustrated. Also, the generally lower levels of trace elements in plant material and the lower availability of minerals from these food sources has been well established. Of the newer trace element deficiencies, zinc impoverishment appears to be especially important, as a state of physiological zinc deficiency rapidly follows dietary insufficiency, and the consequences on all growing tissues are particularly serious. In general, recent developments suggest that marginal deficiencies of microelements are more widespread in human nutrition than was previously appreciated. Greater attention to trace element status seems to be indicated in circumstances in which physical condition and vigour are unaccountably poor and especially in situations accompanied by active anabolism.