Covid-19 and the co-administration of Vitamin C and quercetin! To be

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) represents an emerging global threat that is overwhelming the world's healthcare capacity. In the effort to study and develop adequate pharmacological treatments for its prevention and treatment, the co-administration of vitamin C with quercetin presents interesting results, as it exerts a synergistic antiviral action due to the overlap of antiviral and immunomodulatory properties and the ability of ascorbate to recycle quercetin, increasing its efficacy.

Quercetin is a bioactive compound belonging to the flavonoids, and there is an enormous amount of literature supporting its antiviral properties. Quercetin inhibits various respiratory viruses in cultured cells, and it inhibits the cytopathic effects caused by many serotypes of rotaviruses, echoviruses, coxsackieviruses, and polioviruses.

In turn, vitamin C is an essential nutrient involved in a wide range of immune functions. Its supplementation has shown beneficial effects in various types of viral infections. Reduced ascorbate levels have been found in patients with viral infections, sepsis, and other critical illnesses. During infection, vitamin C is necessary for neutrophil killing, concentrates in macrophages; furthermore, it is responsible for T-cell maturation and promotes phagocytosis and apoptosis of exhausted neutrophils.

In a review, Biancatelli, 2020, proposes a multi-drug approach for prophylaxis in high-risk populations and for the treatment of mild cases with 250mg-500mg quercetin and 500mg vitamin C. For severe cases, it indicates doses of 500mg quercetin and 3g vitamin C for 7 days. This approach can interrupt viral entry, replication, enzymatic activity, and assembly, while simultaneously strengthening the immune response by promoting early IFN (Interferon-γ) production, modulating interleukins, and promoting T-cell maturation and phagocytic activity.

The co-administration of quercetin and ascorbic acid represents an experimental strategy for the prophylaxis and treatment of various respiratory viruses, such as SARS-CoV-2. Blocking viral entry is a key strategy, and quercetin prevents viral membrane fusion for influenza and SARS-CoV.

In conclusion, this review strongly suggests, due to the lack of severe side effects and low cost, the combined administration of these two compounds for the prophylaxis and early treatment of respiratory tract infections, especially including patients with COVID-19.

Reference: Colunga Biancatelli RML, Berrill M, Catravas JD, Marik PE. Quercetin and Vitamin C: An Experimental, Synergistic Therapy for the Prevention and Treatment of SARS-CoV-2 Related Disease (COVID-19). Front Immunol. 2020 Jun 19;11:1451. doi: 10.3389/fimmu.2020.01451. PMID: 32636851; PMCID: PMC7318306.

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