Marginal zinc deficiency in older adults: responsiveness of zinc status indicators.

Abstract

Mild zinc deficiency is difficult to detect. In this study, traditional indicators such as plasma zinc and alkaline phosphatase did not change as would be expected in response to alterations in zinc intake. Likewise, erythrocyte metallothionein did not respond to altered zinc intakes as expected but this factor may reflect long-standing or more severe zinc depletion and thus requires additional study. Activity of the enzyme 5'-nucleotidase appears responsive to acute changes in zinc intake; however, more work is needed to define how well these activities will reflect zinc intake in other types of subjects.