Abstract
Simultaneous zinc and vitamin A deficiency are common health problems in developing countries. The objective of this study was to assess effect of supplementation of high zinc or vitamin A on immune function. After three months of feeding with a zinc and vitamin A deficient diet, mice were assigned into four groups which, for additional two months, received a normal or high zinc along with vitamin A deficient diet and a normal or high vitamin A along with zinc deficient diet. Serum and intestinal mucosa immunoglobulin A (IgA) were determined and supernatants of splenocytes were used to assess interlukin (IL)-2, IL-5, IFN-γ. Mice maintained on zinc deficient diet with normal or high vitamin A resulted in significantly lower production of IFN-γ. Also, supplementation of high dose vitamin A augmented production of the cytokine as compared to normal intake of the vitamin. Supplementation of either normal or high zinc along with low vitamin A diet significantly led to higher production of IFN-γ as compared to those receiving zinc limited but adequate vitamin A. High intake of zinc along with vitamin A deficient diet significantly enhanced secretion of IL-2. Levels of serum and mucosal IgA and IL-5 were not be significantly modulated. Moreover, animals fed with high doses of zinc showed increased IL-2 production than those that had normal intake of zinc. Results indicated that zinc and vitamin A supplementation up-regulates production of T-cell cytokines, IFN-γ and IL-2.
Highlights
Effective function of the immune system as the most important contributor to maintenance of good health and defense against infections is strongly affected by nutriational status
Mice maintained on zinc deficient diet with normal or high vitamin A resulted in significantly lower production of IFN-γ
Animals kept on a high vitamin A with low zinc diet had significantly more (P < 0.05) food intake as compared with the others, whereas, this group had negative weight gain and less feed efficiency as compared with the other groups
Summary
Effective function of the immune system as the most important contributor to maintenance of good health and defense against infections is strongly affected by nutriational status. Zinc is among the most important micronutrients involved in modulation of immune function. It is recognized to be present in almost every cell, known to support the healthy immune system and needed for wound healing [3]. It regulates several functions of lymphocytes, such as mitogenesis [4], antibody synthesis [5], activation of T cells and natural killer cells, and cellular immunity [6]. Flattening of villi, decreased numbers of crypts, inflammatory cell infiltration of the lamina propria and lesions of intestinal mucosa have been reported in both experimental animals and humans suffering from ZD [12,13,14]
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