ZINC IN HUMAN HEALTH

However, beside the specific organ systems zinc is very important during
development and ageing. Both will be discussed in separate chapters to show the
importance especially during childhood, which is the main problem in developing
countries, and during ageing, which is the main problem in the industrial world.
Before the reader starts with this textbook some general remarks have to be made.
Whenever zinc is described the Zn2+ ion is meant, since zinc as a transition element
exists only in this oxidation state. Elementary zinc does not have any biological
function, it is only the Zn2+ ion. Furthermore, different terms are used as “available”,
“loosely bound”, “exchangeable”, “chelateable”, “flexible” or “free” zinc. All terms
describe the free cytoplasmic or extracellular zinc which can mediate the effects due to
a fast transfer to active sites of enzymes and other proteins. Therefore free zinc is the
best term to used, but all terms are used in this book.