Vitamin C, or ascorbic acid, is a water-soluble vitamin well known for its role in supporting a healthy immune system.

Vitamin C contributes to immune defense by supporting various cellular functions of both the innate and adaptive immune system.

Vitamin C supports epithelial barrier function against pathogens and promotes the oxidant scavenging activity of the skin, thereby potentially protecting against environmental oxidative stress. Vitamin C accumulates in phagocytic cells, such as neutrophils, and can enhance chemotaxis, phagocytosis, generation of reactive oxygen species, and ultimately microbial killing.