Cereal Chem 58:18 - 21.  |  VIEW ARTICLE
Interrelationships Among Protein, Zinc, and Copper in Human Nutrition.

S. J. Ritchey. Copyright 1981 by the American Association of Cereal Chemists, Inc. 

Recent research suggest interactions among protein, zinc, and copper, with the possibility that the absorption and utilization of the trace elements are affected. Although reports from animal studies indicate that protein metabolism is altered by low zinc intakes, investigations with human subjects do not confirm this when zinc intakes are marginal. High protein intakes may cause increased urinary excretion of zinc, but this is not clearly documented, as for calcium. The absorption of copper is difficult to evaluate in the usual balance method with human subjects because of the route of excretion. A few studies in which both protein and copper were variables do not indicate any effect of protein on copper retention, but this relationship appears not to have been investigated in humans. Most human studies indicate that zinc does not alter the utilization of copper, but at least one study with humans and reports from animal models suggest an antagonistic effect and decreased retention of copper when the intake of zinc is elevated. Data from several human studies indicate that the apparent absorption of copper ranges from 0 to 60% and of zinc from 7.1 to 62.1%. In most studies, the apparent absorption of zinc is in the range of 20-35%. The possibility exists that the interrelationship among protein, copper, and zinc is important to human health; thus further investigations seem to have merit.