Low-molecular-weight zinc-binding ligand: a regulatory modulator for intestinal zinc transport

1. In the last two decades, vast numbers of studies on the zinc nutriture of animals and man have been made. However, the biochemical and physiological events in controlling zinc nutrition are still poorly understood. This report concerns the progress made toward understanding the intestinal zinc absorption and secretion mechanisms. 2. Evidence is accumulating that zinc absorption is a facilitated diffusion while zinc secretion is an active transport. 3. It is known that a low molecular weight zinc-binding ligand (LMW-ZBL) is a key regulator of intestinal zinc absorption, possibly a carrier molecule across the intestinal mucosal cells. Some high molecular weight zinc-binding ligands also appear to be involved in regulating intestinal zinc transport. 4. The identity of the LMW-ZBL is a matter of controversy and its specific role in regulating intestinal zinc transport is not well defined. 5. According to the available literature, no systemic investigations have been made to elucidate the intestinal zinc transport mechanisms, and much more information is needed to fully understand them.