Copper bioavailability and requirements.

Knowledge of factors affecting the bioavailability of dietary copper is limited. Intestinal absorption of copper appears to be facilitated by L-amino acids. Picolinic acid has a favorable binding affinity for copper and may facilitate its absorption. Measurements of the dietary requirements for copper in adult men have shown the requirement to range from about 1.5 to 2.0 mg daily, levels similar to the 2.0 mg estimate suggested in the past. Comparison of the copper requirements with the levels of copper present in some contemporary diets suggests that marginal copper nutriture may not be rare. Persons who consume diets high in zinc and low in protein are at risk of copper deficiency. High intakes of sources of dietary fiber apparently increase the dietary requirement for copper. Studies in one man have shown that signs of mild copper deficiency can be produced experimentally when a conventional diet containing about 0.8 mg of copper is fed. At this time, the 2 to 3 mg daily intake of dietary copper suggested by the National Research Council (63) seems appropriate.