By Steve Blechman

An article was recently published in the June 19, 2020 journal Frontiers in Immunology entitled: Quercetin and Vitamin C: An Experimental, Synergistic Therapy for the Prevention and Treatment of SARS-CoV-2 Related Disease (Covid-19). The article states, “Quercetin is a well-known flavonoid whose antiviral properties have been investigated in numerous studies. There is evidence vitamin C and quercetin co-administration exerts a synergistic antiviral action due to overlapping antiviral and immunomodulatory properties.” Also, the ability of vitamin C to recycle and enhance the benefits of quercetin. The researchers noted, “The article presents 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.”

Quercetin has a long history as an antioxidant with anti-inflammatory and anti-blood clotting effects in the Mediterranean diet. Quercetin is very abundant in red grapes and red wine. There is a great amount of research supporting the antiviral properties of quercetin and polyphenols in the scientific literature. It has been shown in the literature that overtrained athletes supplemented with quercetin and vitamin C help protect them from upper respiratory tract infections.

Research has shown over the years that vitamin C, quercetin, and other polyphenols, found in grapes, are important antioxidants in the body that lower inflammation. Selenium, N-acetylcysteine (NAC) and zinc are important antioxidants in the body that can lower inflammation. When a virus particle enters your body through your nose, mouth or eyes, into your lungs, the immune system recognizes the virus and sends immune-signaling molecules called cytokines such as interleukin-6 (IL-6) and tumor necrosis factor (TNF). Normally these cytokines play a beneficial role by activating our innate immune response and certain white blood cells called macrophage, neutrophils and natural killer cells that destroy and kill certain dangerous pathogens, bacteria and viruses. These white blood cells are like killer, phagocytic Pac-Men that release reactive oxygen species (ROS) free radicals and kill these bacteria and viruses at the same time these ROS free radical species damage normal tissues and can cause inflammation and cell death. So these white blood cells in fact are a two-edged sword – they kill dangerous viruses and bacteria, or they can go haywire, causing severe inflammation, cell damage and organ failure. Antioxidant nutrients such as vitamin C, polyphenols, selenium, zinc and N-acetylcysteine (NAC) have been shown in the scientific literature to be potent scavengers of ROS and free radicals, helping to lower inflammation in the lungs and other organs and tissues.

Polyphenols such as quercetin and grape skins and grapeseed extract are effective and work synergistically with vitamin C as antioxidants, having anti-inflammatory and antiviral properties. Quercetin appears to prevent viruses from entry in the cell, thereby reducing viral load (Viruses, December 2016). Polyphenols also function as prebiotics and help promote healthy bacteria flora. Curcumin, a polyphenol found in the spice turmeric, has anti-inflammatory properties. There are no studies that demonstrate curcumin prevents or reduces viral infections in humans. One concern is that curcumin may increase the expression of the ACE2 receptor that makes it easier for the virus to enter the cell. This is controversial, and more research is needed to clarify this.

There currently are no products or dietary supplements that are scientifically proven to treat or prevent the coronavirus, according to the U.S. Food and Drug Administration (FDA). Still, some unethical supplement companies have promoted fraudulent cures and claims and treatments not based on good science, such as colloidal silver products for coronavirus. The FDA has cautioned that colloidal silver is not a safe or effective treatment for any disease or condition! By law, companies are not allowed to make claims on their product labels or ads that the product is intended to diagnose, treat, cure or prevent any disease.  

Research in the scientific literature has shown that certain immune dietary supplements and nutrients such as zinc, vitamin D, vitamin C, selenium, N-acetylcysteine, and polyphenols have potential immune modulating benefits. I was so pleased by a recently reported Cleveland Clinic study! Researchers published a scientific review article (June 2, 2020, Cleveland Clinic Journal of Medicine) entitled: What is the role of supplementation with ascorbic acid, zinc, vitamin D, or N-acetylcysteine for prevention or treatment of COVID-19? This is a very important and significant article and requires further investigation and research. The Cleveland Clinic has pioneered many medical breakthroughs and has been known for many years as one of the best hospitals and medical institutions in the United States. 

In conclusion, the article says “quercetin displays a broad range of antiviral properties that can interfere at multiple steps of pathogen virulence – to separate virus entry, virus replication, protein assembly – and these therapeutic effects can be augmented by the co-administration of vitamin C. Furthermore, due to their lack of severe side effects and low costs, we strongly suggest the combined administration of these two compounds for both the prophylaxis and the early treatment of respiratory tract infections especially including COVID-19 patients.” 

©Published by Advanced Research Media, Inc. 2020

©Reprinted with permission from Advanced Research Media, Inc.

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