This nutrient is probably the best-known for fighting all kinds of sickness and infection. The way vitamin C works in the immune system is by improving various components’ functions, including NK cell activity and white blood cell proliferation. Ensuring an adequate level of vitamin C at all times supports immune system function because when extreme stress or infection occurs, vitamin C levels in the blood quickly decline. Vitamin C keeps cells stable and less vulnerable to oxidative stress and inflammatory response.
Some white blood cells, most notably T-cells and phagocytes, collect vitamin C and can’t function without it. Deficiency in this essential nutrient lowers our resistance to pathogens but ample quantities optimize immune system function. Vitamin C has been shown to reduce the duration of infection once it occurs. (38)
Additionally, vitamin C reduces the risk of contracting an infectious disease (including colds) and its severity once it’s affected us. (39) Furthermore, recent studies have shown that high doses of vitamin C will target cancerous cells, causing their death, while leaving healthy cells intact. The importance of vitamin C as an immune system booster should be considered in the broader long view: adequate vitamin C is critical for cardiovascular health, strong bones, moderating blood pressure, building collagen (for skin and connective tissues), and reduced cancer risk. You can get vitamin C in almost all vegetables and fruits, though some more than others. Load up to keep your immunity in tip-top shape.