Vitamin C is essential micronutrient for humans, with functions are: Vit C being a potent antioxidant has the ability to donate electrons. Important Enzymes are released by Vit C . which promotes GENE regulation. Various cellular functions of both the innate and adaptive immune system for immune defense are contributed by Vit C. Epithelial function against pathogens and oxidant scavenging activity of the skin are supported by Vit C and protects against the environmental oxidative stress caused by the gene regulatory. Enhancement of chemotaxis and phagocytosis are enhanced by Vit C. and ultimately microbial killing. Vit C supports apoptosis and scavenging of the spent neutrophils from sites of infection by macrophages, there by decreases necrosis. Vit C deficiency leads to Impaired immunity and higher susceptibility to infections. Vit C both prevents and treats respiratory and systemic infections Dietary vitamin C is required for Prophylactic and prevention of infection (100-200 mg/day), which optimize cell and tissue levels. In contrast, treatment of established infections requires significantly higher doses of Vit C to compensate for the increased inflammatory response and metabolic demand.