Current status of zinc in health and disease states.

Even though brass, a zinc-copper alloy, had been known for centuries, metallic zinc was not isolated in Europe until 1509. The metal was then named zinken because of its superficial similarity to tin (German-zinn) (Wootton, 1910). Zinc (atomic number 30; atomic weight 65 37) has a completed d subshell with 2 s electrons and the divalent cation is the only naturally occurring oxidation state. This relative stability, its ability to co-ordinate 4 or occasionally 6 ligands, and its capacity to act as a Lewis acid are probably fundamental to zinc's biological role. The biological importance of zinc was first discovered when Raulin (1869) demonstrated that it was necessary for the growth of Aspergillus niger. Subsequently, the ubiquitous distribution of zinc in nature was appreciated and the essentiality of zinc for higher plants (Maze, 1914) and animals (Todd et al., 1934) was established. In man the medicinal use of calamine (zinc carbonate) is first recorded in Papyrus Ebers of 1550 BC (Ebers, 1937) but it was not until 1939 that it was suggested that zinc deficiency might contribute to the clinical manifestations of human vitamin deficiency syndromes such as beriberi (Eggleton, 1939). The first human zinc deficiency syndrome was identified in the early 1960s in malnourished adolescent boys in Iran and Egypt (Halsted et al., 1972). A more profound deficiency state became apparent when Moyanhan and Barnes (1973) showed that treatment with zinc induced a complete and rapid clinical remission in a patient with acrodermatitis enteropathica.