Metabolic balance studies for zinc and nitrogen in healthy elderly subjects.

Metabolic balances for zinc and nitrogen were performed in ten healthy elderly men and women aged 72.2 to 85.4 yr whilst they were living in their own homes. The mean daily retentions of nitrogen and zinc were 29 mmol (range-38 to +179) and 4 micromol (range -17 to +16) respectively. The mean concentrations of zinc were 11.9 micromol/1 plasma (lower than in younger adults) and 89.8 micromol/1 whole blood (similar to that of younger adults). There was no significant correlation between these values nor was there correlation with the overall retention of zinc. The balance data provide reference values against which the findings in malnourished, sick and institutionalized elderly may be better assessed.