Plasma and leucocyte zinc concentrations and their response to zinc supplementation in an elderly population

Plasma, mononuclear cell and granulocyte zinc were assessed in a group of 15 institutionalised elderly female patients, and the effect of different levels of zinc supplements (50, 100, 150 mg elemental zinc/day) on these parameters was measured. Plasma but not cellular zinc was lower in the elderly compared with a young control group, but a diminished serum albumin may explain the plasma results. Plasma zinc increased with supplementation, but only when the daily intake was 100 or 150 mg/day; the greatest response was with the higher dose. Mononuclear cell zinc did not respond to zinc supplements. There was a decrease in granulocyte zinc at all levels of zinc supplements, the greatest decrease being found with the highest dose (150 mg/day). The decrease in granulocyte zinc at high intakes may have implications in phagocytosis and chemotaxis.