The most common and most stable oxidation number of zinc is +2 [Zn(II)]. Zinc is a ubiquitous trace element found in plants and animals. The adult human body contains approximately 1.5–2.5 g of zinc, present in all organs, tissues, fluids and secretions. The level of free intracellular Zn(II) is as low as 0.5 nM, as estimated from measurements of the zinc-specific 19F-NMR signal of a fluorinatedmetal chelating probe (Benters et al., 1997).
Zinc is an element present in more than 70 different enzymes that function in many aspects of cellular metabolism, involving metabolism of proteins, lipids and carbohydrates.
Zinc deficiency may cause growth retardation and hypogonadism in humans (Prasad et al., 1961). Other symptoms of zinc deficiency include loss of appetite, dermatitis, reduced taste acuity, delayed wound healing, impaired reproduction and poor immune function. Zinc helps manage insulin action and blood glucose concentration and has an essential role in the development and maintenance of the body’s immune system.
Severe zinc deficiency is rare and usually caused by genetic or acquired conditions. Zinc has an antioxidant effect and this may have benefited a few cases of hepatitis. Zinc intake seems also promising to inhibit herpes simplex virus (Kumel et al., 1990) and rhinoviruses (Korant et al., 1974).