Better than Hydroxychloroquine? Two New Studies Show Quercetin Improves COVID Outcomes

Better than Hydroxychloroquine? Two New Studies Show Quercetin Improves COVID Outcomes – Easier to Get


Dr. Joseph Mercola and Dr. Robert Gorter

October 18th, 2021


Two studies suggest that this antiviral, anticoagulant, and anti-inflammatory agent is an alternative to hydroxychloroquine. In addition, it is much less expensive, easier to obtain, and COVID clears up faster than those given painkillers and antibiotics. Where are the media?.

Two recently published studies confirm that quercetin is useful as adjunctive therapy in the early outpatient treatment of mild SARS-CoV-2 infection

In one study, the virus cleared more quickly in SARS-CoV-2 patients who received quercetin in addition to analgesics and an antibiotic than those who received only painkillers and antibiotics, and a greater number of patients reported a reduction in symptoms.

In the second study, the daily addition of quercetin for one month reduced the frequency and length of hospitalization, the need for non-invasive oxygen therapy, intensive care, and death rates.

Quercetin has antiviral, anticoagulant, anti-inflammatory, and antioxidant properties, all of which are important in the treatment of SARS-CoV-2 infection.

Quercetin also inhibits the binding of specific spike proteins to your ACE2 receptors, blocking the virus from its ability to infect your cells. It has also been shown to directly neutralize viral proteins critical for SARS-CoV-2 replication.

In a newsletter dated August 21, 2021, 1, Dr. Michael Murray’s use of quercetin for the symptoms of respiratory infections. In November 2020, he had had a “very mild and brief bout of COVID-19” and one of his “secret weapons,” he believes, may have been quercetin.

He also tells of an anecdotal story of a friend who developed suspicious respiratory symptoms. His friend had taken some supplements that were said to provide protection, but still wasn’t feeling well.

As it turned out, the only thing he hadn’t taken was quercetin, and as soon as he did, that same day, his symptoms began to subside. This experience, Murray says, “concurs with the results of two clinical studies” recently published.

Quercetin appears to be a very safe, much cheaper, and more readily available alternative to hydroxychloroquine, and it works through a similar mechanism, driving zinc into the cells to stop viral replication.

Statistical Improvement of Clinical Outcomes

In the first study, 2 were 42 COVID-19 outpatients divided into two groups. One group of 21 patients received standard medical therapy consisting of analgesics and an antibiotic (acetaminophen 500-milligram (mg) to 1000-mg dose if body temperature was above 37.5 degrees C – 99.5 F – with a maximum daily dose of 3 grams, and 500 mg of azithromycin for three consecutive days).

The other group of 21 patients received standard therapy plus the equivalent of 600 mg quercetin per day (divided into three doses) for seven days, followed by a further seven-day course of 400 mg quercetin per day (divided into two doses).

The quercetin used was a brand name formulated with sunflower lecithin, which has been shown to increase absorption in the gut by up to 20 times, compared to pure quercetin formulations.

The main results evaluated were virus removal and symptoms. After one week of treatment, 16 of the 21 patients in the quercetin group tested negative for SARS-CoV-2, and 12 reported that all symptoms had subsided.

In the standard group, only two tests were negative and four had partially improved symptoms. At the end of week 2, the five remaining patients in the quercetin group had tested negative. In the standard care group, 17 of the 19 remaining patients had a negative test result and one of them had died.

As noted by the authors, “quercetin supplementation statistically shortens the timing of molecular test conversion from positive to negative, simultaneously reducing symptom severity and negative predictors of COVID-19.”

“These results are impressive and hopefully additional studies will be conducted on hospitalized patients to see how quercetin could be helpful in more severe cases,” Murray wrote in his newsletter.

Quercetin reduces hospitalizations and deaths

The second study 3 – a prospective, randomized, controlled, and open-label study – gave 152 COVID-19 outpatients a daily dose of 1,000 mg quercetin for 30 days to evaluate its adjuvant effects in the treatment of early symptoms and prevention of serious infections. According to the authors:

“The results revealed a reduction in frequency and length of hospitalization, in need for non-invasive oxygen therapy, in progression to intensive care units, and in death rates. The results also confirmed the very high safety profile of quercetin and suggested possible anti-fatigue and appetite-promoting properties.

QP (Quercetin Phytosome®) is a safe agent and, when used in the early stages of a viral infection with standard care, may help improve early symptoms and prevent the severity of COVID-19 disease. It is suggested that a double-blind, placebo-controlled study be conducted urgently to confirm the results of our study.”

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Mechanisms of Action

As noted in the first study 4 above, quercetin was chosen based on the fact that it has antiviral, anti-blood clotting, anti-inflammatory, and antioxidant properties, all of which are important in the treatment of SARS-CoV-2 infection. In the second study, more detailed mechanisms of action are discussed. According to the authors: 5

“SARS-CoV-2 proteases, such as 3-chymotrypsin-like protease (3CLpro), papain-like protease (PLpro), RNA-dependent RNA polymerase, spike (S)protein, and human angiotensin-converting enzyme 2 (hACE2 ) are considered potential targets for the development of effective anti-COVID-19 drugs.

Recently, molecular docking studies have suggested the possible binding interaction of quercetin with the 3CLpro, PLpro, and S-hACE2 complex. Some recent results obtained with biophysical techniques seem to support the results of the molecular docking studies.

Quercetin, a flavonol not naturally present in the human body, is the most abundant polyphenol in fruits and vegetables and is widely used as a dietary supplement to boost the immune system and promote a healthy lifestyle.

Quercetin is characterized by three crucial properties:

1) antioxidant,

2) anti-inflammatory

3) immunomodulatory.

The combination of these actions makes quercetin a potential candidate to support all unhealthy conditions involving oxidative stress, inflammation, and immunosuppression.”

Initially, quercetin attracted attention as a potential treatment for SARS-CoV-2 infection because it is a zinc ionophore, meaning it brings zinc – which has known antiviral effects – into your cells, much like the drug hydroxychloroquine.

In particular, quercetin significantly inhibits the binding of specific spike proteins to ACE-2 receptors, blocking the virus’ ability to infect human cells. Quercetin has also been shown to directly neutralize viral proteins critical in SARS-CoV-2 replication.

Some argued that the main reason hydroxychloroquine and quercetin worked was because of this property. Of course, you also had to take zinc along with one of these remedies. To work effectively as a zinc ionophore, quercetin also needs vitamin C.

Since then, other studies, including the two discussed here, have shown that quercetin has other actions that also make it useful against SARS-CoV-2. As Murray reports in his newsletter:

“In particular, quercetin significantly inhibits the binding of specific spike proteins to ACE-2 receptors, blocking the virus’ ability to infect human cells. Quercetin has also been shown to directly neutralize viral proteins critical in SARS-CoV-2 replication.”

Quercetin has also been shown in some studies to inhibit the release of pro-inflammatory cytokines, which could help alleviate infection-related symptoms and suppress excessive inflammatory responses. The antioxidant activity of quercetin may also help prevent tissue damage caused by scavenging free radicals, aiding the recovery process from viral infections. 6

Quercetin’s Antiviral Properties in General

Quercetin’s antiviral properties are attributed to three main mechanisms of action:

  • Inhibiting the ability of the virus to infect cells
  • Inhibiting the replication of already infected cells
  • Reducing the resistance of infected cells to antiviral treatment

For example, study 7, funded by the US Defense Advanced Research Projects Agency (DARPA) and published in 2008, found that it lowers your risk of viral illnesses like the flu and improves your mental performance after extreme physical stress, which could otherwise undermine your immune function and could make you more prone to (viral) infections.

Cyclists given a daily dose of 1000 mg quercetin in combination with vitamin C (which increases plasma quercetin levels 8,9 ) and niacin (to improve absorption) for five weeks were significantly less likely to develop a viral disease. walking after cycling for three hours a day for three consecutive days, compared with untreated controls. While 45% of the placebo group got sick, that was only 5% of the treated group.

Quercetin works against common cold and flu viruses

Before the COVID-19 pandemic hit, several studies had already shown that quercetin is able to prevent and treat the common colds and seasonal flu. 10,11,12,13,14,15,16,17,18 By reducing oxidative damage, it also lowers the risk of secondary bacterial infections, 19 which is actually the leading cause of deaths from flu.

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Importantly, quercetin increases mitochondrial biogenesis in skeletal muscle, suggesting that some of the quercetin’s antiviral effects are due to enhanced mitochondrial antiviral signaling. 20 Quercetin also works against other viruses, as shown by the following studies:

  • A 1985 study showed that quercetin inhibits the infectivity and replication of herpes simplex virus type 1, poliovirus type 1, parainfluenza virus type 3, and respiratory syncytial virus (RSV). 21
  • An animal study from 2016 22 showed that quercetin the dengue virus and hepatitis virus are inhibited in mice.
  • Other studies have confirmed that quercetin is able to inhibit both hepatitis B 23 and C 24 infections.

A March 2020 study25 found that quercetin provides “comprehensive protection” against Streptococcus pneumoniae infection, both in vitro and in vivo, primarily by neutralizing pneumolysin (PLY),26 one of the toxins released from pneumococci that inhibit the S pneumonia infection in the first place.

Streptococcus pneumonia is not only responsible for pneumonia but can also be involved in some ear and sinus infections, meningitis, and certain blood infections. 27 As reported by the authors of this study: 28

“The results indicated that quercetin significantly reduced PLY-induced hemolytic activity and cytotoxicity via suppression of oligomer formation.

In addition, quercetin treatment may reduce PLY-mediated cell damage, improve the survival rate of mice infected with a lethal dose of S. pneumoniae, alleviate pathological damage of lung tissue, and release cytokines (IL-1β and TNF-α) in bronchoalveolar lavage fluid. to slow down.

Given the importance of these events in the pathogenesis of antimicrobial-resistant S. pneumonia, our results indicate that quercetin could be a new potential drug candidate for the treatment of clinical pneumococcal infections.”

How quercetin fights inflammation and boosts immunity

In addition to its antiviral activity, quercetin is also known for boosting immunity and fighting inflammation. As noted in a 2016 study 29 in the journal Nutrients, its mechanisms of action include (but are not limited to) the inhibition of 30

  • Lipopolysaccharide (LPS)-induced tumor necrosis factor α (TNF-α) production in macrophages. TNF-α is a cytokine involved in systemic inflammation and is secreted by activated macrophages, a type of immune cell that digests foreign substances, microbes, and other harmful or damaged components
  • LPS induces mRNA levels of TNF-α and interleukin (IL)-1α in glial cells, resulting in “reduced apoptotic neuronal cell death”
  • The production of pro-inflammatory enzymes the influx of calcium into the cell, which in turn inhibits the release of pro-inflammatory cytokines, as well as the release of histamine and serotonin by intestinal mast cells 31
  • According to this paper, quercetin also stabilizes mast cells, has cytoprotective activity in the gastrointestinal tract, and has “a direct regulatory effect on the basic functional properties of immune cells,” enabling it to “inhibit a vast panoply of molecular targets in the micromolar concentration range, either by down-regulating or suppressing many inflammatory pathways and functions. “ 32

Although quercetin has potent antiviral activity, it takes a high enough dose to increase the level of quercetin in your body’s tissues to be effective.

The relatively slow absorption rate of quercetin is why a sunflower lecithin formula, sold under the brand name Quercetin Phytosome®, has been used in the two featured studies discussed at the beginning of this article. However, that is not the only option.

Study 33 published in the July-December 2021 issue of the Journal of Natural Health Products Research found that Quercetin LipoMicel Matrix™ has the same total absorption rate as Quercetin Phytosome – and higher peak levels in the blood.

“Since both these forms of quercetin produce similar blood levels, they should have the same effects at equal doses based on quercetin levels,” Murray wrote in his newsletter, adding:

“My dosing recommendation as part of a nutritional supplement program to support immune function in the prevention of COVID-19 is Quercetin LipoMicel Matrix™ 250 mg BID.

And in patients with active COVID-19, my recommendation is… six capsules of Quercetin LipoMicel Matrix™ twice daily, totaling 3000 mg of quercetin in this enhanced form. This high dose should be taken for at least 10 days and then reduced to a maintenance dose of 250mg twice daily…

[This] high dose may not be necessary. But my dosage calculations are based on likely tissue concentrations needed to exert the strongest antiviral effects. And given the safety of quercetin, there is no harm at this level.”

Early treatment protocol with quercetin

One doctor who put quercetin in the spotlight early on in the COVID pandemic was Dr. Vladimir Zelenko. When hydroxychloroquine became difficult to obtain, Zelenko switched to quercetin because it is readily available as an over-the-counter supplement. For a downloadable “cheat sheet” of Zelenko’s protocol for COVID-19, visit

Other Health Benefits of Quercetin

There are other lesser-known benefits and uses of Quercetin, including the prevention and/or treatment of 34

  • High blood pressure 35.36
  • Cardiovascular disease 37
  • Obesity 38 and metabolic syndrome 39 (a cluster of conditions including high blood pressure, high blood sugar, high triglyceride levels, and fat accumulation around the waist that increase the risk of type 2 diabetes, heart disease, and stroke)
  • certain types of cancer, especially leukemia, and to a lesser extent breast cancer 40
  • Non-Alcoholic Fatty Liver Disease (NAFLD) 41
  • gout 42
  • arthritis 43
  • mood disorders 44
  • aluminum-induced neurodegenerative changes, such as those seen in Alzheimer’s, Parkinson’s and amyotrophic lateral sclerosis (ALS) 45
  • Life extension, thanks to the hemolytic action (clearing damaged and worn cells) 46.47

Research has also shown the epigenetic influence of quercetin and its ability to: 48

  • Interaction with cell signaling pathways
  • modulate gene expression
  • Influencing the activity of transcription factors
  • Modulate microRNAs

MicroRNAs used to be considered “junk” DNA. But research has shown that so-called “junk” DNA is actually microRNA and plays a vital role in regulating genes that make the proteins that make up your body.

The microRNAs act as “on/off” switches for the genes. Depending on the microRNA input, a single gene can encode one of over 200 protein products. Quercetin’s ability to modulate microRNA may also help explain why it has cytotoxic effects and why it appears to improve cancer survival (at least in mice).

Sources and references:


2,  4  International Journal of General Medicine June 2021; 14: 2807-2816

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6  Journal of Natural Health Product Research July-December 2021; 3(2) Rationale for Quercetin as a Potential Supplement to Increase Resistance to COVID

7  American Journal of Physiology August 1, 2008

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22  Asian Pacific Journal of Tropical Medicine Jan 2016; 9(1): 1-7

23  Virologica Sinica August 2015; 30(4): 261-268

24  Hepatology 2009 Dec;50(6):1756-64

25,  28  Microbial Pathogenesis March 2020; 140: 103934

26  Clinical & Experimental Immunology Nov 2004; 138(2): 195-201

27  CDC Pneumococcal Disease

29  Nutrients 2016 Mar; 8(3): 167, 5.2.1 Animal Models

30,  32  Nutrients 2016 Mar; 8(3): 167, 5.1.2 Mechanism of Action

31  Nutrients 2016 Mar; 8(3): 167, Table 1: Mast cell

33  Journal of Natural Health Product Research July-December 2021; 3(2)

34  Genetic Life Hacks December 17, 2019

35  J Am Heart Assoc. 2016 Jul 12;5(7). pii: e002713

36  Nutrition Reviews January 6, 2020 DOI: 10.1093/nutrit/nuz071

37  Int J Mol Sci. 2019 Dec 3;20(23). pii: E6093

38  Obesity (Silver Spring). 2008 Sep;16(9):2081-7

39  Phytotherapy Research March 8, 2019; 33(5)

40  Scientific Reports April 12, 2016; 6 Article Number: 24049

41  Phytotherapy Research August 26, 2019 DOI: 10.1002/ptr.6486

42  Br J Nutr. 2016 Mar 14;115(5):800-6

43  J Am Coll Nutr. 2017 Jan;36(1):9-15

44  Fitoterapia 2015 Oct;106:256-71

45  Neuroscience 2016 Jun 2;324:163-76

46  EBioMedicine. 2019 Sep;47:446-456

47  BMB Rep. 2019;52(1):47–55

48  Molecules 2019 Dec 23;25(1). pii: E63

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