A review of the role of vitamin d in autoimmunity

Introduction: The main function of vitamin D is to increase the intestinal absorption of calcium, participating in the stimulation of active transport of this ion in enterocytes. Extra-renal hydroxylation of vitamin D also occurs, originating the vitamin that would act in an autocrine and paracrine manner, with functions of inhibiting cell proliferation, promoting cell differentiation, and immune regulation. Objective: It was to review the scientific literature on the role of vitamin D in autoimmunity. Methods: A search was carried out on scientific articles centered on the proposed theme: “Role of vitamin D in autoimmunity”. Several search engines that carried scientific information in the health area were used to carry out this study, such as Google Scholar and the Medical Publications database (PubMed), and Scientific Electronic Library Online (SCIELO). In collecting the information, the descriptors used to carry out this research were: vitamin D; vitamin D in preventing diseases; vitamin D and autoimmune diseases; vitamin D; autoimmune diseases. The inclusion criteria used in this study were publications of scientific articles available in full and with free electronic access, limited to a period between 2011 and 2022, and selected articles in Portuguese and English. Results and Conclusion: Based on this methodology, it was possible to analyze a population of 58 articles that were selected for the study and constituted the sample used in this review. Several studies point to the effects of vitamin D not related to calcium metabolism, such as antineoplastic activity (particularly concerning breast, colon, and prostate cancers, and lymphoproliferative diseases), antihypertensive and immunomodulatory. Vitamin D deficiency and its use for treatment have been described in various autoimmune diseases such as rheumatoid arthritis, multiple sclerosis, lupus, inflammatory bowel disease, myasthenia gravis, scleroderma, alopecia areata, psoriasis, vitiligo, autoimmune hepatitis, type 1 diabetes mellitus, autoimmune thyroiditis, etc. The effects of vitamin D on the immune system are related to the tolerance of self-antigens, exerting an inhibitory effect on the Th1 and Th17 type lymphocyte pattern, and a promoting effect on the expression of the Th2 and Treg pattern through the action of vitamin D in all cells of the system through the vitamin D receptor. More studies are needed to establish safe and effective doses in the management of these properties of vitamin D.