The Multifaceted Role of Vitamin D: From Synthesis to Clinical Implications

Abstract

Vitamin D, a secosteroid hormone pivotal to numerous physiological processes, has garnered extensive attention due to its dual origin from sunlight exposure and dietary intake. Structurally characterized by its cholesterol-derived backbone, vitamin D exists primarily as ergocalciferol (D2) and cholecalciferol (D3), with serum 25-hydroxyvitamin D [25(OH)D] levels between 30–100 ng/mL considered optimal for health. Beyond its classical role in calcium homeostasis and bone mineralization, emerging research underscores its immunomodulatory, anti-inflammatory, and metabolic functions. Deficiencies, prevalent globally, correlate with pathologies ranging from osteoporosis to cardiovascular diseases, while toxicity, though rare, poses risks of hypercalcemia. This review synthesizes current knowledge on vitamin D’s synthesis, mechanisms, diagnostic approaches, and therapeutic strategies, offering a comprehensive perspective on its indispensability in human health.