As we have already seen in another article, vitamin C has different roles in our body: here we will focus on the ones dealing with immune system.
The first barrier against microorganisms is skin: it is important to keep it intact in order to avoid the entrance of pathogens. Vitamin C helps to maintain the integrity of skin by stabilizing the structure of collagen, enhancing the expression of tight junction proteins (proteins which help cells to stay close together) and preventing the cytoskeletal rearrangements. It also favours wound healing by inducing proliferation and migration of fibroblasts, cells which secrete collagen ﬁbers, the major component of the dermis.
Neutrophils are the first cell type recruited when an infection occurs: in this cells vitamin C seems to have more than one important role.
Neutrophils go through oxidative burst (so they produce Reactive Oxygen Species-ROS) to kill pathogens, and vitamin C is thought to have both an antioxidant effect in the host cells themselves and enhance the ROS production in order to kill the microorganisms, even if improvements given by the supplement of this molecule depend on the type of microorganism (some are more susceptible to non oxidative mechanisms) and on the baseline of vitamin C present in the organism.
Moreover, after their action is done, neutrophils die by apoptosis and their clearance by macrophages is necessary to prevent an inflammation status. Vitamin C enhances both these processes and it also inhibits NETosis (a microbial killing method which involves the release of ‘neutrophil extracellular traps’ -NETs- comprising neutrophil DNA, histones, and enzymes) which could lead to major tissue damage and inflammation.
The inflammation is decreased also by the production of antiinflammatory cytokines and the reduced production of proinflammatory ones induced by vitamin C, even if, also in this case, the efficacy of the supplement depends on the cell type and/or the inflammatory stimulant.