Trace element requirements in humans: An update

Abstract

Concepts about nutrient intake requirements and recommendations have emerged from a period of relative consensus about concepts and goals to one of vertiginous shifts of paradigms and a proliferation of agendas, often competing, for making nutrient and dietary recommendations in public policy. The recommendations for intakes of those trace elements considered to be essential in human nutrition are updated in the context of the ferment and controversy regarding how to establish a recommended intake. It is our contention that making universal recommendations for the intake of trace elements to cover all societies among the diverse geographic and ecological settings of the world is a futile effort. Differences in ethnicity, body size, traditional diets, genetics, and environmental stressors condition distinct needs at distinct locations. It is speculated that lower than “usual” body stores of certain trace elements may be adaptive, i.e., to improve human survival under certain adverse and challenging environmental conditions. Additionally, gaps in our knowledge regarding the bases for nutrient recommendations in the very old and the impact of new, engineered foods and dietary guidelines for intake regimes that prevent chronic diseases need to be filled. As trace elements are inorganic and can accumulate in tissues, recommendations for usual intakes confront the issue of the upper limits of tolerance and potential toxic consequences. Iron, copper, and manganese are among the trace elements for which this consideration is ever latent. The community of scientists involved in trace element biology must follow closely the chaotic situation regarding changing paradigms and agendas of oral intake recommendations, participate in the discussions when called upon, but continue to produce new findings. J. Trace Elem. Exp. Med. 11:177–195, 1998. © 1998 Wiley-Liss, Inc.