Effects of dietary zinc restriction on postprandial changes in plasma zinc

The principal objective of this study was to determine the effect of a short period of severe dietary zinc restriction on both prebreakfast and postbreakfast plasma zinc concentrations. After an overnight fast, plasma zinc was measured in five normal adults before and at 30-min intervals for 6 h after a standard zinc-free test meal. This test was performed after a week on a zinc-adequate diet and repeated after a week of severe dietary zinc restriction. Postabsorptive premeal plasma zinc did not change after a week of severe dietary zinc restriction but the posttest meal decline was significantly greater and the maximum decline less variable (15-23%). It is concluded that postprandial plasma zinc is more sensitive than prebreakfast plasma zinc to dietary zinc depletion. Recent zinc intake is one factor that determines the magnitude of the postprandial net efflux of zinc from the plasma compartment.