In infections and excessive inflammatory processes, vitamin D occupies an important position as a regulator of the adapted immune response 1.
Study results show that an adequate supply of vitamin D significantly reduced the risk of COVID-19 infection 1. In the case of infectious pathogens, vitamin D can stimulate epithelial cells to release antimicrobial peptides, known as AMPs, and thus contribute to the immune response. These peptides play an important role especially in areas where there is no distinct mucosal barrier. Similarly, supplemental intake of vitamin D in patients with inflammatory bowel diseases has been shown to promote maintenance of the intestinal barrier 1. Conversely, inflammatory bowel disease was associated with vitamin D deficiency in the majority of the studied patients 1. The immune modulatory function of vitamin D can be attributed to the vitamin D receptor signaling pathway, which can influence the perception of microbial signals and initiate appropriate counter-reactions. The signals triggered by vitamin D and the vitamin D receptor are able to suppress excessive inflammatory responses of the body, which would otherwise be harmful 1. The effects of vitamin D to ramp up the immune defense and, if necessary, to inhibit the triggered inflammatory responses again, underline the immense importance of vitamin D for physical health and homeostasis.
- Hamza, F. N. et al. Immunomodulatory Properties of Vitamin D in the Intestinal and Respiratory Systems. Nutrients 15, 1696 (2023).