Table 1.

Role of vitamin C in immune defense.

Immune System	Function of Vitamin C	Refs.
Epithelial barriers	Enhances collagen synthesis and stabilization	[30,31,32,33,34,35]
	Protects against ROS-induced damage 1	[36,37,38,39,40]
	Enhances keratinocyte differentiation and lipid synthesis	[41,42,43,44,45]
	Enhances fibroblast proliferation and migration	[46,47]
	Shortens time to wound healing in patients	[48,49]
Phagocytes (neutrophils, macrophages)	Acts as an antioxidant/electron donor	[50,51,52,53]
	Enhances motility/chemotaxis	[54,55,56,57,58,59,60,61,62,63]
	Enhances phagocytosis and ROS generation	[64,65,66,67,68,69,70,71]
	Enhances microbial killing	[54,55,57,58,70,72]
	Facilitates apoptosis and clearance	[71,73,74]
	Decreases necrosis/NETosis	[73,75]
B- and T-lymphocytes	Enhances differentiation and proliferation	[62,63,76,77,78,79,80,81,82]
	Enhances antibody levels	[78,83,84,85]
Inflammatory mediators	Modulates cytokine production	[75,77,86,87,88,89,90,91,92,93,94]
	Decreases histamine levels	[56,61,95,96,97,98,99,100,101]

¹ ROS, reactive oxygen species; NET, neutrophil extracellular trap. Note that many of these studies comprised marginal or deficient vitamin C status at baseline. Supplementation in situations of adequate vitamin C status may not have comparable effects.