The role of vitamin A and its metabolites in the immune system and host susceptibility is discussed in a series of reviews [77, 78]. This nutrient is involved in normal differentiation of epithelial tissue, furthermore retinoic acid is essential for imprinting T and B cells with gut-homing specificity and T array cells and IgA cells in intestinal tissues [79], thus enhancing the intestinal immune response and supporting the intestinal barrier [80]. Carotenoids (both provitamin A and non-provitamin A carotenoids) have immunoregulatory actions including the reduction of the toxic effects of ROS and the regulation of membrane fluidity and gap-junctional communication [81].