Vitamin C is water soluble and acts as a cofactor in hydroxylation reactions, which are required for collagen synthesis. It is an essential water-soluble nutrient which primarily exerts its effect on host defense mechanisms and immune homeostatsis by being the most important physiological antioxidant. It is also involved in a variety of other biochemical functions such as hormone synthesis, wound healing, and iron absorption.Vitamin C has been shown to inactivate a host of viruses upon exposure. It has been implicated as hoaving both a preventative and a therapeutic role in a variety of diseases including scurvy, viral infections and common cold, cancer and atherosclerosis.It also protects neutrophils from oxidation.

Part of vitamin C’s protective benefit is due to its antioxidant action. Oxidative stress increases the antioxidant requirements of the white blood cell macrophages and lymphyoctes. Vitamin C supplementation increases antioxidant glutathione concentration in lymphocytes and normalizes monocyte adhesion to endothelial cells. Oxidative damage plays a key role in endotoxin (LPS)-induced spesis leading to an inappropriate activation of the transcription factor NFkB and, subsequently, to an overexpression of inflammatory proteins. Vitamin C may protect from dysregulation of the immune-inflammatory response by its antioxidant properties. Long used against the common cold, vitamin C has shown mixed results. However, a 2002 study involving 180 British subjects found supplementation could prevent the common cold, as well as limit severe symptoms and shorten the duration.

Fourt independent double-blind studies have reported that ascorbic acid reguraly ingested in dialy amounts more than 100 mg decreases the incidence as well as the severity of colds in comparison with a placebo.

During active infection this nutrient is quickly depleted thus increasing the body’s need. The current RDI is 60 mg.

Foods Rich in Vitamin C: Food sources include citrus fruits, strawberries, mellons, tomatoes, broccoli and peppers (especially red). The body’s rate of absorption of Vitaimn C is often not greater than 1 g hour, so divided doeses are important. Second, if taking large doeses, rebound scurvy can develop if the individual abruptly stops taking the vitamin.