Zinc—the immunity mineral we forget about?

Aim of the study: After the discovery of zinc deficiency in the 1960s, it soon became clear that zinc is essential for the function of the immune system. Zinc ions are involved in regulating intracellular signaling pathways in innate and adaptive immune cells.

Results: Consequently, the benefits of zinc supplementation for a malfunctioning immune system become clear. This article will focus on underlying mechanisms responsible for the regulation of cellular signaling by alterations in zinc homeostasis. Effects of fast zinc flux, intermediate "zinc waves", and late homeostatic zinc signals will be discriminated. Description of zinc homeostasis-related effects on the activation of key signaling molecules, as well as on epigenetic modifications, are included to emphasize the role of zinc as a gatekeeper of immune function.

Aim of the study: Nutritional deficiency of zinc is widespread throughout the developing countries and a conditioned deficiency of zinc is known to occur in many diseased states. Zinc is known to play an important role in the immune system and zinc deficient subjects may experience increased susceptibility to a variety of pathogens.

Results: T cell subpopulation studies revealed that the CD4+ CD45RA+ to CD4+ CD45RO+ ratio was decreased as a result of zinc deficiency, suggesting that zinc may be required for the regeneration of new CD4+ T cells. We further documented that zinc deficiency decreased NK cell lytic activity and caused a decrease in the percentage of CD8+ CD73+ T cells which are known to be predominantly precursors of cytotoxic T cells. In a suitable cell culture model our studies revealed that the gene expression of a DNA synthesizing enzyme TK was affected adversely which resulted in delayed cell cycle and decreased cell growth. The above immunological consequences of zinc deficiency may be responsible for decreased cell mediated immune functions in zinc deficient subjects.

Aim of the study: Vitamin C concentrations in the plasma and leukocytes rapidly decline during infections and stress. Supplementation of vitamin C was found to improve components of the human immune system such as antimicrobial and natural killer cell activities, lymphocyte proliferation, chemotaxis, and delayed-type hypersensitivity.

Results: in the elderly. A large number of randomized controlled intervention trials with intakes of up to 1 g of vitamin C and up to 30 mg of zinc are available. These trials document that adequate intakes of vitamin C and zinc ameliorate symptoms and shorten the duration of respiratory tract infections including the common cold. Furthermore, vitamin C and zinc reduce the incidence and improve the outcome of pneumonia, malaria, and diarrhea infections, especially in children in developing countries.

Aim of the study: Zinc is known to be essential for all highly proliferating cells in the human body, especially the immune system. A variety of in vivo and in vitro effects of zinc on immune cells mainly depend on the zinc concentration.

Results: High dosages of zinc evoke negative effects on immune cells and show alterations that are similar to those observed with zinc deficiency. Furthermore, when peripheral blood mononuclear cells are incubated with zinc in vitro, the release of cytokines such as interleukins (IL)-1 and -6, tumor necrosis factor-alpha, soluble IL-2R and interferon-gamma is induced. In a concentration of 100 micro mol/L, zinc suppresses natural killer cell killing and T-cell functions whereas monocytes are activated directly, and in a concentration of 500 micro mol/L, zinc evokes a direct chemotactic activation of neutrophil granulocytes. All of these effects are discussed in this short overview.

Aim of the study: Zinc plays an essential role in numerous biochemical pathways. Zinc deficiency affects many organ systems, including the integumentary, gastrointestinal, central nervous system, immune, skeletal, and reproductive systems. This article aims to discuss zinc metabolism and highlights a few of the diseases associated with zinc deficiency.

Results: Zinc deficiency results in dysfunction of both humoral and cell-mediated immunity and increases the susceptibility to infection. Supplementation of zinc has been shown to reduce the incidence of infection as well as cellular damage from increased oxidative stress. Zinc deficiency is also associated with acute and chronic liver disease. Zinc supplementation protects against toxin-induced liver damage and is used as a therapy for hepatic encephalopathy in patients refractory to standard treatment. Zinc deficiency has also been implicated in diarrheal disease, and supplementation has been effective in both prophylaxis and treatment of acute diarrhea.