EC Clinical and Medical Case Reports

Vitamin D is traditionally recognized for its role in calcium homeostasis and skeletal integrity; however, growing evidence highlights its broader immunomodulatory functions. This literature review examines the extra-skeletal importance of vitamin D and synthesizes current findings linking deficiency with treatment-resistant or immune-mediated disease states. Vitamin D influences both innate and adaptive immune pathways through widespread vitamin D receptor (VDR) expression and local activation in immune and epithelial tissues. These mechanisms contribute to its emerging relevance in neurological autoimmune disorders, metabolic dysfunction, chronic inflammatory conditions, and steroid-resistant airway disease. Clinical and translational studies consistently demonstrate that vitamin D deficiency is associated with dysregulated cytokine activity, impaired host defense, reduced glucocorticoid responsiveness, and heightened autoimmunity. Taken together, current evidence underscores vitamin D’s role as a vital immunologic cofactor and supports continued investigation into its therapeutic potential across a range of disease processes.

 Keywords: Vitamin D; Extraskeletal Immunomodulatory; Treatment-Resistant Disease Syndromes

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