Mineral elements: new perspectives.

Research during the 1970s brought out the importance of interrelationships among trace elements and better definition of human mineral requirements. These have practical implications which are pointed up in this paper. For example, iron absorption (important in meeting requirements of women of child-bearing age) can be improved by co-ingestion of ascorbic acid and/or meat, poultry, or fish products. The interplay between calcium and protein metabolism is also summarized. To accommodate as yet incomplete knowledge, the 1980 revision of the Recommended Dietary Allowances has incorporated the concept of "ranges of safe and adequate intakes" for two minerals and six trace elements. Copper and chromium appear to be of special importance, and their adequacy in the diet cannot be taken for granted. The nutrient density of these two elements per 1,000 kcal can be used in assessing intake in broad terms of "poor," "marginal," or "adequate," although this is by no means a quantitative type of judgment.