Are Dietary Guidelines for Trace Elements Needed? The Development of Provisional Recommended Allowances in the USA

Abstract

History has shown that the consumption of a diet well balanced with regard to the major nutrients and derived from a variety of foods furnishes an adequate supply of the essential micronutrients, including trace elements. Imbalances have existed and continue to exist in unusual geochemical environments and in situations where natural catastrophies, economic or medical reasons, restrict the quantity of food choices. Since the beginning of the twentieth century the reliance on a “balanced” diet as an adequate source for all micronutrients has become somewhat questionable. The consumption of refined, partitioned foods and of new food analogues has increased in industrialized societies and completely new foods are manufactured and consumed in large quantities. The impact of these changes on the health and trace element status of the affected populations is not well defined. Although severe trace element deficiencies are extremely rare in the United States and other industrialized countries, marginal intakes of essential trace elements, in some cases resulting in an impaired physiological function are being described with increasing frequency. Some part of the public expresses serious doubts about the adequacy of the modern diet and resort to self supplementation with vitamins and trace elements ranging from zinc to selenium which are freely available in the health food stores.