Quercetin and Vitamin C: prophylactic antiviral support

Dwayne N. Jackson, PhD CSO ATP LAB

From masks to social distancing, there are many things we can do to limit our exposure to viruses circulating in our environment. However, if we are exposed to SARS-CoV-2 (“the coronavirus”) we must be prepared, otherwise the ensuing COVID-19 symptoms may be deadly.

It’s due to the differences in the way our bodies “process” SARS-CoV-2 that decides our fate with COVID-19. This is why one person can test positive for COVID-19 and barely exhibit symptoms, while others may end up in the hospital critically ill.

The best defense is a good offense! Currently, your best defense against SARS-CoV-2 is to maintain a healthy body composition, stay active and fit, and keep blood glucose normalized by eating a healthy high protein diet, rich in vegetables and omega-3 fatty acids. During times like these, when stress and viral load are both high, you should also be supporting healthy immunity by maintaining good sleep patterns, getting some sunshine (vitamin D), avoiding alcohol, and using a few key pharmaceutical grade supplements.

Micronutrient requirements increase significantly in critical illness! Science tells us that the most severe cases of COVID-19 occur in those who are micronutrient deficient. It has been shown that even slight micronutrient deficiencies can become larger health problems in those with COVID-19. This is because micronutrient requirements increase significantly in critical illness, as our bodies respond and work to recover.

NOTE: Supplements are not a cure for diseases like COVID-19, but there are studies that strongly suggest that keeping micronutrients and key supplements topped up during this time may help you fight COVID-19 should you encounter SARS-CoV-2.

VITAMIN C (Ascorbic Acid)
Vitamin C is an essential and potent antioxidant that plays numerous fundamental roles in immune function, including regulation of the genes in our immune system. It plays a vital role in buffering oxidative stress and has shown promising results when administered to the critically ill. Although the vitamin C status of patients with COVID-19 has not yet been reported, it is known that the vitamin C status of patients with environmentally-acquired pneumonia is severely depleted due to elevated oxidative stress from infection.

Quercetin is a flavonoid that is found in abundance in our diet, especially in broccoli, citrus fruits, grapes, apples, and red wine. Its antioxidant, antiviral, anti-inflammatory and anti-cancer effects have been studied extensively and, as such, it has been gaining widespread popularity as a prophylactic for colds and flu. Quercetin blocks the entry and incorporation of SARS-Cov and influenza viruses into cells, which represents one of its key prophylactic anti-viral roles.

There is evidence that stacking vitamin C and quercetin exerts a synergistic antiviral action due to overlapping antiviral and immunomodulatory properties and the capacity of vitamin C to recycle quercetin, increasing its efficacy. Importantly, under conditions of high turnover, quercetin can exert prooxidant effects if vitamin C levels aren’t adequate; thus, it’s important to stack quercetin with vitamin C.

Stacking vitamin C and quercetin may be an effective experimental strategy for prophylaxis and treatment of several respiratory viruses, such as SARS-CoV-2. A supplemental approach to virus protection using quercetin and vitamin C may disrupt virus entry, replication, enzyme activity and assembly, and fortify immune responsiveness in your favour.

SYNER-C is a novel science backed synergistic formulation of vitamin C and quercetin. 
Syner-C by ATP Laboratory combines several highly bioavailable forms of vitamin C with pharma-grade quercetin, bromelain and grapeseed extract. Our R&D team feels that Syner-C is the best vitamin C and quercetin based anti-oxidant/anti-viral nutraceutical your money can buy. For the best protection we recommend using 1-3 capsules of Syner-C, 2-3x per day.


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;11:1451. Published 2020 Jun 19. 

Carr AC, Rosengrave PC, Bayer S, Chambers S, Mehrtens J, Shaw GM. Hypovitaminosis C and vitamin C deficiency in critically ill patients despite recommended enteral and parenteral intakes. Crit Care. 2017;21:300.

Carr AC. Vitamin C in pneumonia and sepsis. In: Chen Q, Vissers M, editors. Vitamin C: new biochemical and functional insights. Oxidative stress and disease. Boca Raton: FL CRC Press/Taylor & Francis; 2020. pp. 115–135.

Carr AC. Micronutrient status of COVID-19 patients: a critical consideration

Critical Care volume 24, 349; 2020.

Carr AC, Spencer E, Dixon L, Chambers ST. Patients with community acquired pneumonia exhibit depleted vitamin C status and elevated oxidative stress. Nutrients. 2020;12(1318):10.

Heinz SA, Henson DA, Austin MD, Jin F, Nieman DC. Quercetin supplementation and upper respiratory tract infection: a randomized community clinical trial. Pharmacol Res 2010; 62: 237–242.

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