Vitamin C is involved in the normal metabolism of tissues, an electron donor (or reducing agent) for intracellular and extracellular chemical reactions, and a natural antioxidant in the body. At the same time, vitamin C is an essential vitamin for the immune system, and a deficiency of vitamin C can affect the immune function of the body.

–Lin Xiaoming, Advanced Nutrition (2nd Edition) [M]. Beijing, Peking University Medical Press, 2017:236

 

Vitamin C can promote the formation of antibodies in the body, improve the phagocytosis of leukocytes, increase the body’s resistance to diseases and tolerance to cold, thus enhancing the body’s immune function.

–Zeng Xiangyun, Physiological function and dietary protection of vitamin C[J]. China Food and Nutrition, 2005,4:53

Animal studies have shown that when vitamin C is deficient, the body’s immune response to infection is abnormal. Vitamin C has an important effect on the function of phagocytes. In vitamin C deficiency, phagocytes are unable to function properly, resulting in decreased resistance to infection.

A large number of controlled trials were conducted in volunteers to assess the effect of vitamin C on the common cold. The results showed that people who regularly took vitamin C at a dose of 200 mg or more per day had a slightly shorter duration of the common cold than those who did not take vitamin C (about 10%).

–Yang Yuexin, Ge Keyou. The Complete Book of Chinese Nutritional Science [M]. Beijing, People’s Health Press, 2019: 337

Vitamin C can promote lymphoblastogenesis, stimulate the proliferative response of lymphocytes, improve the body’s recognition and phagocytosis of foreign or malignant cells, and also increase phagocytic activity. Vitamin C can enhance the chemotaxis of circulating blood neutrophils in healthy people. Vitamin C can also improve the movement of neutrophils and bactericidal function in people with abnormal immune function.

–Lin Xiaoming, Advanced Nutrition (2nd ed.) [M]. Beijing, Peking University Medical Press, 2017:237

Vitamin C spontaneously destroys histamine, so supplementation may help prevent asthma attacks as well as relieve symptoms of respiratory infections.

In patients supplemented with vitamin C, phagocytic neutrophil activity was increased, resulting in a lower rate of infection in patients. Some evidence suggests that taking vitamin C may enhance the viability of natural killer cells, which play a very important role in the immune surveillance of tumor cells early in tumor development.

–Yang Yuexin, Li Ning, Guidelines for the Application of Nutritional Functional Ingredients, Beijing, Peking University Medical Press, 2011:207