VITAMIN C: A POTENT ANTIOXIDANT, ROLE IN ACUTE VIRAL INFECTION

Understanding how a virus damage human cells and organs give us clues for developing a more effective therapy. Viruses cause infections that are often associated with redox modification leading to oxidative stress. Changes in redox homeostasis in infected cells are one of the key events in the pathogenesis of respiratory viral infections in all phases of the disease, contributing to severe inflammatory reaction and subsequent tissue damage. Redox changes to an oxidised state also play a critical role in the activation of numerous cell pathways that are hijacked by viruses to replicate and to suppress the patient’s immune response.

Viruses use several strategies to manipulate host cell to their advantage. Among these, the imbalance of intracellular redox state caused by viruses could play an important role in modulating the activity of several signaling pathways. Oxidative imbalance caused by viral infections, ligand–receptor binding or cytokine storm could result in localised oxidation of reactive residues of redox-sensitive proteins. Increased oxidative stress leads to a systemic inflammatory response due to increased production of cytokines, contributing to ARDS, the key pathology in the high mortality of acute respiratory viral infections. Despite the antiviral role of cytokines in respiratory infections, their overproduction during the cytokine storm is more damaging to lung tissue than the viruses themselves.

As a common immunological defense mechanism, immune cells respond to foreign infection by producing large quantities of reactive oxygen species  to destroy invading organisms. Previous pathological and histological examinations showed that coronaviruses and influenza induced significant down regulation of the airway antioxidant system, leading to lethal lung injury and death from ARDS due to oxidative damage.

C reactive protein (CRP) is raised in many acute viral infections which suggest increased oxidative stress.

Role of vitamin C in viral infection:

Viruses like influenza, corona and rhino viruses increase oxidative stress in the body leading to cellular and tissue damage.  In addition to standard conventional supportive treatments, administration of vitamin C (ascorbic acid or ascorbate), has been shown to be a safe and effective therapy for respiratory viral infections.

Implementation of high-dose vitamin C therapy could dramatically reduce the need for high doses of corticosteroids, antibacterials and antiviral drugs that may be immunosuppressive, adrenal depressive and toxic, complicating the disease course. In order to effectively fight the stubborn viruses, medical professionals should explore readily available pharmaceutical and nutritional therapeutic agents with proven antioxidant, anti-inflammatory and immunosupportive properties.

Vitamin C has many properties that make it a valuable therapeutic agent for respiratory infections. It is a potent antioxidant with anti-inflammatory and immune supportive properties. Vitamin C is a small, water-soluble molecule that readily acts as a one- or two-electron reducing agent for many free radicals and oxidants. Almost all mammals, except for humans, primates and guinea pigs, can synthesise vitamin C in their livers, with increased production during stress. Vitamin C is an essential vitamin that acts as a cofactor for several enzymes and facilitates the production of catecholamines, vasopressin, l‐carnitine, collagen neurotransmitters and cortisol, which are central to cellular function and homeostasis. Additionally, vitamin C plays a significant role in viral infection, including attenuation of the pro-inflammatory response, enhancement of epithelial barrier function, increased alveolar fluid clearance, and prevention of sepsis-associated coagulation abnormalities.

This essential vitamin has a huge role in antiviral activity and immune enhancement. It has been shown that vitamin C is an essential factor in the production of type I interferons during the antiviral immune response. Vitamin C has also been shown to upregulate natural killer cell and cytotoxic T-lymphocyte activity. Other studies have used this vitamin as an inactivating agent both for RNA and DNA viruses, lessening viral infectivity. In addition, vitamin C can detoxify viral products that produce pain and inflammation. Evidence has shown the effectiveness of vitamin C in treating pneumonia and infection owing to its direct inhibitory effects on pathogens. Also, vitamin C is present in the epithelial lining of the respiratory tract where it functions as a local mucosal protecting agent, helping to ameliorate symptoms of upper respiratory tract infection.

A high dose of vitamin C may be a proven therapeutic agent that not only ameliorates oxidative stress and inflammation during acute virus infection, but also suppresses viral replication and improves antiviral immune defense and adrenal function.

Supplemental vitamin C may also provide additional benefits for the prevention of viral infection, shorten the disease course and lessen complications of the disease.