The pleiotropic effects of vitamin D on the various metabolic, anticancer, and immunomodulatory functions of the body based on the presence of vitamin D receptors (VDR) on various cell types has been recognized worldwide now. Of few understood mechanisms of immunomodulatory actions of vitamin D are the suppressive action on the maturation of antigen-presenting cells and decrease in the levels of pro-inflammatory cytokines. Vitamin D deficiency has been implicated in the immune diseases like rheumatic diseases, asthma, psoriasis, and multiple sclerosis. Vitamin D deficiency has been associated with increased frequency and severity of disease flares in rheumatic diseases like lupus and rheumatoid arthritis. Other studies have shown higher prevalence of persistence and evolution in to more definite rheumatic disorder in undifferentiated arthritis and undifferentiated connective tissue disorder patients with vitamin D deficiency. Multiple factors like avoidance of sunlight, the use of corticosteroids and hydroxychloroquine, skin pigmentation, etc. should be considered when evaluating vitamin D levels in these patients, needless to say the consideration of higher-dose supplement for these patients. It is thus prudent that all patients with established or undifferentiated rheumatic diseases are evaluated for vitamin D status and an adequate supplementation is recommended to prevent the associated consequences.
Part of the book: Fads and Facts about Vitamin D