Zinc, copper, and iron balance in elderly men.

Two-3-wk balance studies for zinc, copper, and iron were carried out in six elderly male subjects who were confined to a metabolic unit for a long-term study (12 wk) with constant dietary mineral intake. Average zinc balance was 0.1 +/- 0.05 (mean +/- SEM) and serum zinc increased in all subjects during the course of the study. Average copper balance was 0.06 +/- 0.06 (mean +/- SEM). There was no significant change in serum copper ceruloplasmin, but all were within normal ranges except for elevated serum copper in one subject who appeared to be in negative copper balance. Iron balance appeared to be negative, -0.44 +/- 0.16 (mean +/- SEM), despite improved blood iron parameters in five of six subjects. Results of this long-term balance study suggests that current dietary recommendations of 15 mg of zinc and 2 to 3 mg of copper are adequate for elderly as well as younger adults. However, balance data for individuals must be interpreted with caution, should be used only with other parameters, and should not be relied on exclusively as a basis for dietary recommendations. Additional data are needed to evaluate dietary iron recommendations for elderly men.