Micronutrients, including several vitamins (vitamin A, B6, B12, folate, C, D, E) and trace elements (Zinc, Selenium, Copper, Magnesium), play important roles in supporting the immune system, and thus their deficiencies could increase the susceptibility of a host to infectious diseases [12]. Adequate levels of micronutrients are essential to ensure an effective function of each component of the immune system. Regarding the innate immunity, micronutrients play fundamental roles in maintaining the structural and functional integrity of the physical barriers, such as skin and mucus membranes. Micronutrients are also involved in supporting activity of antimicrobial proteins and chemotaxis of innate cells. Furthermore, several vitamins and minerals contribute to the phagocytic and killing activities of neutrophils and macrophages [13]. Deficiencies of vitamins and select essential minerals also affect several aspects of the adaptive immunity, in particular the humoral response (antibody-mediated) and the cell-mediated immunity.