Adaptation to high and low copper intakes: its relevance to estimated safe and adequate daily dietary intakes

Different approaches are used to determine ideal ranges of intakes and threshold levels of safe intakes for nutrients. A consequence of this is that, for inorganic nutrients particularly, a safe level set by traditional toxicologic procedures might be compromised because it is inconsistent with physiologic observations and customary intakes and because the levels set may allow an inordinately narrow range of safe intakes above the upper limit of recommended intakes. This article used data from studies in animal models and in human volunteers to construct a provisional continuum of adaptive processes and pathophysiologic phenomena associated with a range of copper intakes extending from toxic to deficient to suggest an approach to establishing an acceptable range of intakes for copper that would address simultaneously the advisory and regulatory needs of nutritionists and toxicologists.