Diet is an important regulator of the gastrointestinal microbiota. Vitamin A and vitamin D deficiencies result in less diverse, dysbiotic microbial communities and increased susceptibility to infection or injury of the gastrointestinal tract. The vitamin A and vitamin D receptors are nuclear receptors expressed by the host, but not the microbiota. Vitamin A- and vitamin D-mediated regulation of the intestinal epithelium and mucosal immune cells underlies the effects of these nutrients on the microbiota. Vitamin A and vitamin D regulate the expression of tight junction proteins on intestinal epithelial cells that are critical for barrier function in the gut. Other shared functions of vitamin A and vitamin D include the support of innate lymphoid cells that produce IL-22, suppression of IFN-γ and IL-17 by T cells, and induction of regulatory T cells in the mucosal tissues. There are some unique functions of vitamin A and D; for example, vitamin A induces gut homing receptors on T cells, while vitamin D suppresses gut homing receptors on T cells. Together, vitamin A- and vitamin D-mediated regulation of the intestinal epithelium and mucosal immune system shape the microbial communities in the gut to maintain homeostasis.

饮食是胃肠道微生物群的重要调节剂。维生素A和维生素D缺乏会导致多样性低下的不良生物微生物群落，并增加对胃肠道感染或损伤的易感性。维生素A和维生素D受体是宿主表达的核受体，而不是微生物群。维生素A和维生素D介导的肠上皮和粘膜免疫细胞的调节是这些营养素对微生物群的影响的基础。维生素A和维生素D调节肠上皮细胞上紧密连接蛋白的表达，这对于肠道的屏障功能至关重要。维生素A和维生素D的其他共有功能还包括产生IL-22的先天淋巴样细胞的支持，T细胞对IFN-γ和IL-17的抑制作用，粘膜组织中调节性T细胞的诱导和诱导 维生素A和D具有一些独特的功能；例如，维生素A诱导T细胞上的肠归巢受体，而维生素D抑制T细胞上的肠归巢受体。维生素A和维生素D介导的肠上皮和粘膜免疫系统调节共同影响肠道中的微生物群落，以维持体内稳态。