Why You Shouldn't Turn to Natural Supplements to Fight COVID-19

There's no evidence that supplements prevent COVID-19 or lessen symptoms.

Posted Mar 26, 2020

During this time of global pandemic many people are seeking reliable information about both conventional pharmaceuticals and complementary and alternative medicine (CAM) treatments that may reduce the risk of contracting COVID-19 or lessen the severity of symptoms. Because COVID-19 is a coronavirus some people are taking vitamin C, Echinacea, zinc, and other supplements that may reduce symptoms of the common cold in the hope that the same supplements may also reduce their risk of contracting COVID-19 .

Although some supplements may contribute to overall health, and a few studies investigating the possible effectiveness of select supplements have begun, currently there is no evidence that taking vitamin C, Echinacea, zinc, or any other supplements reduces the risk of becoming infected with COVID-19, or lessens the severity of symptoms in individuals who have already contracted the virus. Relying on a natural supplement may not only place you at greater risk of contracting COVID-19, but may delay the start of appropriate medical treatment. The false belief that taking a supplement may ‘protect’ you from becoming infected with COVID-19 may lead some to not take appropriate precautions that have been shown to mitigate the risk of contracting COVID-19, such as social distancing and avoiding gatherings of more than a few people. In recent weeks, false claims about vitamin C and COVID-19 have been removed from large social media sites such as Facebook, Twitter, and Youtube. If you are concerned that you may be infected with COVID-19 and are experiencing respiratory symptoms such as a persistent cough, and have a fever, it is prudent to urgently contact your family physician for advice and to not rely on any information posted in the popular press or on the internet as a substitute for medical advice.

In this post I comment on the lack of evidence for all-natural supplements both for reducing the risk of contracting COVID-19 and for reducing symptom severity in individuals who are infected.

Vitamin C, D, and Zinc

There is limited evidence that taking vitamin C (ascorbic acid) may reduce the risk of contracting the common cold or reduce the severity of cold symptoms. There is no evidence that taking vitamin C, even at high doses up to 5 gm/day, reduces the risk of contracting COVID-19. Taking high doses of vitamin C can also cause diarrhea and interfere with beneficial effects of some prescription medications. There is limited evidence that taking vitamin D during the winter months may reduce the risk of contracting influenza and other upper respiratory infections.

Over-the-counter zinc preparations are widely used to self-treat the common cold. Research findings suggest that zinc may have anti-viral properties. There is limited evidence that zinc supplementation may reduce the risk of developing an upper respiratory infection, especially in the elderly however there is currently no evidence that zinc supplementation reduces risk of COVID-19 infection

Herbals, quercetin, coconut oil, and medicinal mushrooms

Curcumin, derived from the herb turmeric, is widely used for its general anti-inflammatory benefits. A recently published study found evidence that curcumin may inhibit the coronavirus that causes COVID-19 (in cell cultures), reducing the risk of infection. However, no human clinical studies have been done on curcumin as a treatment of the common cold or influenza, and there is no evidence that curcumin decreases the risk of COVID-19 infection

The extract of elderberry may inhibit replication of the virus that causes influenza and shorten the duration of symptoms. There is no evidence that elderberry reduces the risk of contracting the virus that causes COVID-19 or reduces the severity of symptoms in individuals infected with the virus.

There is inconclusive evidence that the herbal Echinacea may reduce the risk of contracting the common cold. A recently completed study that has not yet been published reported that an extract of Echinacea may inhibit certain coronaviruses; however the virus that causes COVID-19 was not tested.

There is limited evidence that quercetin, found in apples, berries, and onions, may inhibit different viruses including the coronavirus that causes Severe Acute Respiratory Syndrome (SARS). A human clinical trial evaluating quercetin in individuals infected with COVID-19 is now ongoing but no results have been reported.

Coconut oil contains lauric acid which may have anti-viral activity. A study was recently proposed to evaluate the possible efficacy of this natural product against COVID-19 but currently there is no evidence that lauric acid reduces the risk of contracting the virus that causes COVID-19.

Medicinal mushrooms such as Reishi, Shitake, Turkey tail, Maitake, and Cordyceps have been investigated for their putative role in boosting immune function. There is some evidence that Cordyceps may reduce the severity of asthma and upper respiratory infections, but there is no evidence that taking any medicinal mushroom reduces the risk of contracting the virus that causes COVID-19. 

Natural products that are not only ineffective but dangerous

In addition to the above supplements, some natural products not only lack beneficial antiviral effects against the virus that causes COVID-19, but result in potentially serious toxic side effects. Examples include Miracle Mineral Solution (which contains 28% sodium chlorite in distilled water), chlorine dioxide, and colloidal silver. In 2019 the FDA issued a strong warning advising all consumers to not drink Miracle Mineral Solution.

Colloidal silver is a widely used disinfectant used to kill viruses on surfaces, but there is no evidence that ingesting colloidal silver is an effective treatment of the virus that causes COVID-19. Further, when ingested colloidal silver may accumulate in different organs causing severe damage.

Although social media sites have tried to remove false claims about the above products as treatments of COVID-19 there is concern among public health officials that people may read about them and use them with potentially serious health consequences.

Bottom line

There is limited evidence that select supplements may reduce the risk of contracting the common cold or influenza, but there is currently no evidence that any supplement reduces the risk of contracting the virus that causes COVID-19 or lessens the severity of symptoms in infected individuals. Studies investigating possible antiviral effects of select natural products have recently started or are being planned, but these studies are still in very early stages and no findings have been reported. In the absence of reliable information about putative antiviral effects of natural supplements for reducing the risk of contracting the virus that causes COVID-19 or for treating symptoms in infected individuals, relying on any natural supplement to reduce the risk of being infected or to treat symptoms of COVID-19 may place you—and those near you—at unnecessary risk.