RESUMO
Vitamin D is a fat soluble hormone that is majorly involved in the classical function of calcium and phosphorus hemostasis and bone mineralization as well non classical functions of immune modulation in various viral and autoimmune diseases. Both innate and adaptive immunity is aided by vitamin D. Deficiency of vitamin D is not only linked with bone and muscle disorders but it has a critical role in many infectious and noninfectious diseases. A growing body of literature suggests vitamin D deficiency in human immunodeficiency virus (HIV) infected patients. HIV affects 36.7 million people worldwide. Currently a valuation of 0.13 million people are infected with acquired immunodeficiency syndrome (AIDS) in Pakistan. Various studies showed that hypovitaminosis D may aggravate the disease severity in HIV patients by compromising the immune system. Calcidiol supplementation is credibly a promising adjuvant of combination anti-retroviral therapy (cART) for the treatment of HIV by increasing CD4 T-cells and lowering the viral load. This review accentuates vitamin D's functions as an immune modulator in HIV, the effect of hypovitaminosis D in diseases severity, and its supplementation impact on the treatment of HIV infected patients.