Vitamin C is a water soluble micronutrient commonly found in our diet which orchestrates the function of both innate and adaptive immune system, influencing both cellular and humoral immune responses. Vitamin C inhibits excessive activation of the immune system to prevent tissue damage, but also supports antibacterial activity, stimulates NK cells and differentiation of Th0 subset into Th1 characterized by interferon γ production. In addition, vitamin C interferes with the synthesis of proinflammatory cytokines, or with the expression of adhesive molecules. Moreover, vitamin C as an antioxidat protects the immune cells against intracellular ROS (reactive oxygen species) formed in the inflammatory response. Vitamin C as an enzymatic cofactor is extremely important in maintaining tissue integrity, and plays a crucial role in formation of skin, epithelial and endothelial barriers.

Holmannová D, Koláčková M, Krejsek J. Fyziologická úloha vitaminu C ve vztahu ke složkám imunitního systému [Vitamin C and its physiological role with respect to the components of the immune system]. Vnitr Lek. 2012 Oct;58(10):743-9. Czech. PMID: 23121060.