|Shames, Davis - KINETIC ANALYSIS ASSOCIAT|
Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 2000
Publication Date: May 1, 2000
Interpretive Summary: Studies in experimental animals show that whole body zinc content remains constant over a ten-fold range in dietary intakes. The same seems to be true in humans as a result of adjustments in gastrointestinal zinc absorption and endogenous fecal zinc excretion. With extreme reductions in zinc intake, urinary zinc excretion and plasma zinc concentrations also fall. No change in plasma zinc concentration occurs unless the reduction in intake is very severe. Thus, plasma zinc is not a sensitive indicator of who body zinc status.
Technical Abstract: Maintaining a constant state of cellular zinc nutrition, or homeostasis, is essential for normal function. In animals and humans, adjustments in zinc absorption and endogenous intestinal excretion are the primary means of maintaining zinc homeostasis. The adjustments in gastrointestinal zinc absorbtion and endogenous excretion are synergistic. Shifts in endogenous excretion appear to occur quickly with changes in intake just above or below optimal intake. The absorption of zinc responds more slowly, but it has the capacity to cope with large fluctuations in intake. With extremely low zinc intakes or with prolonged marginal intakes, secondary homeostatic adjustments may augment the gastrointestinal changes. These secondary adjustments include changes in urinary zinc excretion, a shift in plasma zinc turnover rates, and, possibly, an avid retention of zinc released from selected tissues, such as bone, in other tissues in order to maintain function.