Regarding immunity, vitamin A contributes to supporting the integrity of epithelia, particularly the gastrointestinal epithelia tissue among children suffering from severe infections or who are undernourished [15]. Vitamin A is also important in regulating the number and function of natural killer (NK) cells, macrophages, and neutrophils [16,17]. By downregulating the expression level of interferon (IFN)-γ and upregulating the secretion of inerleukin (IL)-5, vitamin A plays a regulatory role in the early differentiation stage of NK cells. Moreover, it regulates the differentiation of dendritic cells precursors and promotes the secretion of the pro-inflammatory cytokines IL-12 and IL-23 by dendritic cells. It has also a crucial role in promoting Foxp3+ Treg generation, while reciprocally inhibiting Th1/Th17 generation and a Th9 transcriptional and epigenomic program [20,21]. Furthermore, vitamin A is involved in the antimicrobial action of macrophages, playing a role in the phagocytic and oxidative burst activity [13].