The effect of age on plasma zinc uptake and taste acuity

Plasma uptake of a 25 mg oral dose of zinc was measured at 0, 1, 2, 3, and 4 h postdose in 16 elderly (mean age = 7.25 yr) and 12 young (mean age = 24.0 yr) subjects selected from a group of 62 healthy nonsmokers. Elderly and young subjects were divided into two groups based upon low or high detection thresholds for solutions of sodium chloride and sucrose. Mean fasting concentrations of plasma zinc were almost identical for the two age groups. Plasma response to a zinc dose was lower (p less than 0.05) in the elderly compared to that in the young, as indicated by plasma zinc levels at hours 2 and 3 postdose and by total area under the response curve. Moderate but significant age-associated increases in detection thresholds for both sodium chloride and sucrose were found; taste thresholds were not correlated to plasma uptake of the zinc dose in either age group.