The article reviews the role of vitamin D in immune function, focusing on its effects on both innate and adaptive immune systems. Vitamin D, primarily synthesized in the skin through UVB exposure, plays a crucial role in mineral metabolism and skeletal health. However, recent studies have highlighted its broader impact on human health, particularly in the context of immune regulation. The review discusses how vitamin D modulates the activity of various immune cells, including macrophages, monocytes, and dendritic cells, by converting inactive forms of vitamin D into active forms like calcitriol. This process is essential for maintaining a balanced immune response and preventing autoimmune diseases. The article also explores the relationship between vitamin D deficiency and autoimmune disorders such as type 1 diabetes mellitus (T1D) and multiple sclerosis (MS). While some clinical trials have shown promising results, others have been inconclusive. The authors emphasize the need for more extensive and well-designed clinical trials to fully understand the role of vitamin D in preventing and managing autoimmune diseases. Overall, the review suggests that vitamin D is a promising nutrient for the prevention and treatment of immune-related disorders, but further research is required to optimize its use.The article reviews the role of vitamin D in immune function, focusing on its effects on both innate and adaptive immune systems. Vitamin D, primarily synthesized in the skin through UVB exposure, plays a crucial role in mineral metabolism and skeletal health. However, recent studies have highlighted its broader impact on human health, particularly in the context of immune regulation. The review discusses how vitamin D modulates the activity of various immune cells, including macrophages, monocytes, and dendritic cells, by converting inactive forms of vitamin D into active forms like calcitriol. This process is essential for maintaining a balanced immune response and preventing autoimmune diseases. The article also explores the relationship between vitamin D deficiency and autoimmune disorders such as type 1 diabetes mellitus (T1D) and multiple sclerosis (MS). While some clinical trials have shown promising results, others have been inconclusive. The authors emphasize the need for more extensive and well-designed clinical trials to fully understand the role of vitamin D in preventing and managing autoimmune diseases. Overall, the review suggests that vitamin D is a promising nutrient for the prevention and treatment of immune-related disorders, but further research is required to optimize its use.