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Quercetin and Vitamin C – More Options for fighting Covid-19?

While quercetin may not be quite as well-known as other immune strengthening ingredients, it is quite common in healthy diets. In fact, this flavonoid polyphenol compound is found in many foods, including apples, grapes, onions, tea, and various herbs.

There’s no doubt that a diet rich in foods that contain quercetin and vitamin C foods can help you stay healthy, but there’s also plenty of research that backs up the use of quercetin especially as a nutrient for fighting viral infections.

In fact, scientific studies show that pretreatment with quercetin is the best way to stop viruses from replicating, and has effectively blocked H1N1 within 48 hours. Other in vitro work found that quercetin inhibited rhinovirus replication within 24 hours. Other laboratory research has found that quercetin reduces bronchial inflammation and moderates the immune response to prevent it from going into overdrive. It is considered a valuable natural antiviral in cases of influenza A virus, and most likely, can help stop many others as well.

Quercetin activates T-helper cells (Th-1) that produce interferon-gamma (INF-y), a cytokine that, in turn, activates macrophages that hunt down and destroy viral and bacterial invaders. Quercetin also balances Th-2 cells to keep the immune responses helpful, and not too severe.

Researchers in Italy, one of the nations with an early (and especially deadly), outbreak of Covid-19 have proposed that both quercetin and vitamin C be used as synergistic nutrients for preventing and for treating the virus as an adjunct medicine along with conventional medications.

Quercetin can be difficult for the body to absorb consistently, so when adding it as a supplement, it’s wise to find a form that combines it with an absorption booster such as gamma cyclodextrin. Vitamin C, an immune enhancer on its own, helps the body recycle quercetin, so it is a good partner nutrient as well.



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.

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) represents an emergent global threat which is straining worldwide healthcare capacity. As of May 27th, the disease caused by SARS-CoV-2 (COVID-19) has resulted in more than 340,000 deaths worldwide, with 100,000 deaths in the US alone. It is imperative to study and develop pharmacological treatments suitable for the prevention and treatment of COVID-19. Ascorbic acid is a crucial vitamin necessary for the correct functioning of the immune system. It plays a role in stress response and has shown promising results when administered to the critically ill. Quercetin is a well-known flavonoid whose antiviral properties have been investigated in numerous studies. There is evidence that vitamin C and quercetin co-administration exerts a synergistic antiviral action due to overlapping antiviral and immunomodulatory properties and the capacity of ascorbate to recycle quercetin, increasing its efficacy. Safe, cheap interventions which have a sound biological rationale should be prioritized for experimental use in the current context of a global health pandemic. We present the current evidence for the use of vitamin C and quercetin both for prophylaxis in high-risk populations and for the treatment of COVID-19 patients as an adjunct to promising pharmacological agents such as Remdesivir or convalescent plasma.

Here is the link to the complete article: Quercetin and Vitamin C: An Experimental, Synergistic Therapy for the Prevention and Treatment of SARS-CoV-2 Related Disease (COVID-19)

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Terry is happy to provide his opinion on diet and nutrition, supplements and lifestyle choices. This information is for educational purposes only. It is not meant to replace the advice of your physician and is not to be considered medical advice, diagnosis or treatment. Should you have any concerns please contact your physician directly.
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