Zinc deficiency in humans is characterized by a reduction of IL-2 and IFN-γ. A randomized double-blind, placebo-controlled trial of zinc supplementation was conducted in elderly people (Prasad et al., 2007). The zinc supplementation decreased incidence of infections and ex vivo generation of TNF-alpha and plasma oxidative stress markers than in the placebo group. Zinc supplementation was effective in decreasing incidences of infections in the elderly patients with sickle cell disease (Bao et al., 2008) and has beneficial effect on respiratory tract infections

in children (Veverka et al., 2009). Zinc may have a preventive role in some cancers such as colon and prostate and in atherosclerosis inasmuch as chronic inflammation has been implicated in the development of these disorders. Clinical trials have confirmed that the group taking zinc supplements had a shorter mean overall duration of cold and shorter duration of cough. The results CB-839 of zinc supplementation in AIDS are contradictory (Bobat et al., 2005). It has been observed that

only zinc deficient patients would respond to zinc supplementation and zinc sufficient patients may not have any beneficial effects. More studies are needed in this respect. Zinc supplements Y27632 intake together with IFN-alpha was more effective against chronic hepatitis C than therapy with IFN-alpha alone (Takagi et al., 2001). It is also possible that 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) Digestive enzyme and rhinoviruses

(Korant et al., 1974). While one study reported the beneficial effects of zinc supplementation with respect to joint swelling in patients with rheumatoid arthritis, two other studies did not confirm this observation (Overbeck et al., 2008). Preventive effects of zinc supplemention in a group receiving zinc gluconate have shown significantly decreased incidence of infections and ex vivo generation of TNF-alpha and plasma oxidative stress markers with respect to a placebo group (Prasad et al., 2007). The zinc-supplemented group of patients with sickle cell disease had decreased incidences of infection in comparison to the placebo group (Bao et al., 2008). After zinc supplementation, antioxidant power increased. In addition, plasma nitrite and nitrate (NOx), lipid peroxidation products, DNA oxidation products, and soluble vascular cell adhesion molecule-1 (VCAM-1) decreased compared to the placebo group. Since oxidative stress and chronic inflammation may play important causative roles in many chronic diseases, including atherosclerosis, cancers, neurological disorders, and autoimmune diseases, more thorough studies exploring the status of zinc deficiency and supplementation are necessary. Lead has atomic number 82 (symbol Pb) and is one of the heavy metals.