Zinc and Quercetin: An Effective Antiviral for COVID-19?

Zinc is a well known supplement that is generally contained in standard multivitamins. It provides immune support amongst other functions. Zinc inhibits coronavirus replication and is a general stimulant of antiviral immunity (source). Higher levels of intracellular zinc showed to increase intracellular pH; which affect on RNA-dependent RNA polymerase and decreases the replication mechanism of RNA viruses (e.g. COVID-19). Therefore, zinc ionophores (e.g. Quercetin) can likely be used with zinc supplement to act as antiviral against many RNA viruses including influenza and COVID-19. Suggested benefits of zinc supplementation along with zinc ionophores to prevent and treat COVID-19 and other respiratory tract infections are supported by countless studies (source). In most cases, prophylactic and early use of zinc supplementation was more effective than late therapeutic proceedings. Up to 30% of the everyday respiratory infections, briefly named “common cold,” are due to infections with coronaviruses. Studies showed reduced symptom severity, reduced frequency, and duration of the common cold after zinc administration depending on dosage, zinc compound and the start time after initial symptoms (source).

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Zinc deficiency is very common especially in the elderly, diabetics, cancer patients, asthma, immunosuppressed and obese - all of which have higher levels of mortality for COVID-19. Furthermore, zinc deficiency is associated with increased risk of infectious disease, pneumonia and severity of COVID-19. Conversely, zinc supplementation is associated with a significant decrease in COVID-19 mortality as long as it is delivered with a zinc ionophore (source). 

In short, a balanced zinc homeostasis is essential. Zinc supplementation improves the mucociliary clearance, strengthens the integrity of the epithelium, decreases viral replication, preserves antiviral immunity, attenuates the risk of hyper-inflammation, supports anti-oxidative effects and thus reduces lung damage and minimizes secondary infections. Especially older subjects, patients with chronic diseases and most of the remaining COVID-19 risk groups would most likely benefit.

Quercetin is a natural antihistamine and anti-inflammatory plant pigment that boosts your immune system and may work to control viral replication, according to some research. It allows zinc to exert its proven antiviral properties; in treating COVID-19, quercetin may also lower inflammation, help clear mucus, prevent ventilator-induced damage and support immunity.

Foods high in quercetin include onions, kale, tomatoes, broccoli, asparagus, berries, red wine, citrus fruits, cherries, and tea. 

According to the research, quercetin has been shown to help fight obesity, Type 2 diabetes, circulatory dysfunction, chronic inflammation and mood disorders. It has even been found to help lower blood pressure. Researchers have found that quercetin can trigger tumor regression and begin the process of apoptosis. This is programmed cell death, without which cells can grow uninterrupted and develop into cancerous growths.

Quercetin was initially found to provide broad-spectrum protection against SARS coronavirus in the aftermath of the SARS epidemic that broke out across 26 countries in 2003. Quercetin has also been found to have antiviral activity in Influenza A, Ebola and Zika viruses. Now, some doctors are advocating its use against SARS-CoV-2, in combination with vitamin C, noting that the two have synergistic effects.

Quercetin helps zinc by acting as a zinc ionophore (PubMed 2014), the same mechanism of action that hydroxychloroquine has via helping zinc pass the cell wall where it might halt viral replication.

This zinc ionophore activity of quercetin facilitates the transport of zinc across the cell membrane. It is known that zinc will slow down the replication of coronavirus through inhibition of enzyme RNA polymerase (PubMed 2010). 

The COVID-19 is an RNA (RiboNucleicAcid) virus and requires the RNA polymerase to replicate. Do take note that the study publication was a 2010 publication and is referring to a different coronavirus as compared to the latest coronavirus (COVID-19); though both are from the same family of coronaviruses.

Zinc is safe and well-tolerated. The FLCCC I-MASK+ protocol recommends 30 - 40 mg/day (elemental zinc) for COVID-19 prevention and 100 mg/day for treatment. Zinc lozenges are preferred. While better absorbed on an empty stomach, the most common side effect is nausea and that is much less common when taken with food, so do take it after a meal.

The percentage of elemental zinc varies by form. For example, approximately 23% of zinc sulfate consists of elemental zinc; thus, 220 mg of zinc sulfate contains 50 mg of elemental zinc (Ref). Zinc picolinate (20% of elemental zinc), zinc ascorbate (15%), zinc chloride (48%), zinc carbonate (52%), zinc citrate (31%), zinc bisglycinate (25%) (Ref) and zinc gluconate (14%) and zinc oxide (80%) (Ref).

As for quercetin, the FLCCC I-MASK+ protocol recommends 250 mg/day for COVID-19 prevention and 250 mg twice a day for treatment. 

That said, quercetin is less potent than HCQ (hydroxychloroquine) as a zinc transporter, and it does not reach high concentrations in lung cells that HCQ does. Quercetin may help reduce risk of viral illness if you are basically healthy. But it is not potent enough to replace HCQ for treatment of COVID once you have symptoms, and it does not adequately get into lung tissue. However, if you simply cannot get hydroxychloroquine or ivermectin, quercetin is a viable stand-in. Quercetin works best when taken with vitamin C and Bromelain, as vitamin C helps activate it and bromelain helps with the absorption. 

Update: 

• Recently, Ivermectin has come to the fore as a more effective (also long standing, cheap, generic drug), in all three stages of COVID-19.