Have you ever heard that taking vitamin D supplements or following a ketogenic (keto) diet will protect you from the new coronavirus? In this Special Feature, we explain why these and other persistent myths are not grounded in science.

person scrolling on smartphoneShare on Pinterest
Some coronavirus claims keep making an appearance, but most are not grounded in scientific fact.

Coronavirus data

All data and statistics are based on publicly available data at the time of publication. Some information may be out of date. Visit our coronavirus hub for the most recent information on COVID-19.

Was this helpful?

Even before the World Health Organization (WHO) declared the new coronavirus outbreak a “pandemic,” their director general, Dr. Tedros Adhanom Ghebreyesus, warned of the danger associated with spreading false information about the virus.

At a conference on February 15, 2020, he declared that “we’re not just fighting an epidemic; we’re fighting an infodemic.”

“Fake news spreads faster and more easily than this virus and is just as dangerous,” he emphasized.

However, it can be difficult to tell what is credible and what is not given the sheer quantity of information that people are sharing both on and offline.

Previously on Medical News Today, we compiled a list of 28 myths surrounding the new coronavirus (SARS-CoV-2). In this Special Feature, we will take an in-depth look at five more persistent myths and explain why people should not take them at face value.

Coronavirus resources

For more advice on COVID-19 prevention and treatment, visit our coronavirus hub.

Was this helpful?

Some articles claim that if a person takes vitamin D supplements, they will be less likely to contract SARS-CoV-2.

In part, people have based these claims on a controversial paper that appears in the journal Aging Clinical and Experimental Research.

The paper’s authors claim to have found a correlation between low mean levels of vitamin D in the populations of certain countries and higher rates of COVID-19 cases and related deaths in those same countries.

Based on this correlation, the authors hypothesize that supplementing the diet with vitamin D may help protect against COVID-19. However, there is no evidence to suggest that this would actually be the case.

In a rapid review of the evidence published on May 1, 2020, researchers from the Centre for Evidence-Based Medicine at the University of Oxford in the United Kingdom unequivocally conclude: “We found no clinical evidence on vitamin D in [the prevention or treatment of] COVID-19.”

They also write that “[t]here was no evidence related to vitamin D deficiency predisposing to COVID-19, nor were there studies of supplementation for preventing or treating COVID-19.”

Other researchers who have conducted reviews of the existing data surrounding a potential relationship between vitamin D and COVID-19 agree.

One report by specialists from various institutions in the U.K., Ireland, Belgium, and the United States — which appeared in BMJ Nutrition, Prevention & Health in May 2020 — also points to a lack of supporting evidence in favor of taking vitamin D supplements to prevent infection with SARS-CoV-2.

The report’s authors warn that:

“[C]alls [for high dose vitamin D supplementation as a preventive strategy against COVID-19] are without support from pertinent studies in humans at this time, but rather based on speculations about presumed mechanisms.”

They also note that although sufficient vitamin D can contribute to overall good health on a day-to-day basis, taking supplements without first seeking medical advice can be harmful.

For example, taking too much vitamin D in the form of a dietary supplement could actually jeopardize health, especially among people with certain underlying chronic conditions.

Another widespread rumor is that taking zinc supplements could help prevent infection with SARS-CoV-2 or treat COVID-19.

It is true that zinc is an essential mineral that helps support the functioning of the human immune system.

Starting from this notion, a team of researchers from Russia, Germany, and Greece hypothesized that zinc might be able to act as a preventive and adjuvant therapeutic for COVID-19. Their results appear in the International Journal of Molecular Medicine.

The researchers refer to in vitro experiments that apparently showed that zinc ions were able to inhibit the action of a certain enzyme that facilitates the viral activity of SARS-CoV-2.

However, they also point out the lack of actual clinical evidence that zinc might have an effect against SARS-CoV-2 in humans.

Other papers that cite the potential of zinc as an adjuvant in COVID-19 therapy — including one that appears in Medical Hypotheses — are more speculative and not based on any clinical data.

In a “Practice patterns and guidelines” paper from April 2020 — which appears in BMJ Nutrition, Prevention & Health — nutritionist Emma Derbyshire, Ph.D., and biochemist Joanne Delange, Ph.D., reviewed existing data about zinc (alongside other nutrients) in relation to viral respiratory infections.

They found that, according to available research in humans, zinc supplementation may help prevent pneumonia in young children, and that zinc insufficiency may impair immune responses in older adults.

However, they note that there is not enough evidence about the role of zinc supplementation in preventing viral infections in general.

“Rigorous trials […] are yet to determine the efficacy of zinc supplementation,” they write.

Vitamin C is another essential nutrient that has received a lot of attention. Many people believe that it can prevent or even cure the flu or common cold.

Although it is true that sufficient vitamin C can help support immune function, current evidence regarding its effectiveness in treating or preventing colds and influenza is limited and often contradictory.

Despite this, there have been claims that this vitamin might help fight infections with the new coronavirus.

It is possible that people are basing these claims on an existing ongoing clinical trial in China, which is looking at the effects of high dose intravenous (IV) vitamin C on hospitalized patients receiving care for severe COVID-19.

The researchers expect to complete the trial by the end of September 2020. No results are available in the interim.

Commenting on the trial, experts from the Linus Pauling Institute — which focuses on health and nutrition — at Oregon State University in Corvallis explain that although high dose IV vitamin C might help alleviate COVID-19 symptoms in severely ill patients, regular vitamin C supplements are very unlikely to help people fight off infections with SARS-CoV-2.

The experts warn that “IV vitamin C is not the same as taking vitamin C supplements,” as they would never raise blood levels of this vitamin as highly as an IV infusion would.

They also warn people who may be tempted to up their dosage of vitamin C of the fact they could end up taking too much and experiencing adverse side effects.

Keto diets, which are high in fats and low in carbohydrates, have also received some attention in the context of treating or preventing COVID-19.

This may be because there is some evidence to suggest that keto diets could help boost the immune system. However, much of that evidence is based on animal studies rather than human trials.

Also, an upcoming clinical trial from Johns Hopkins University in Baltimore, MD, proposes to look at whether or not a ketogenic intervention might help intubated COVID-19 patients by reducing inflammation.

The intervention would necessitate the administration of a specially devised ketogenic formula through enteral feeding. It would be a last-resort procedure for those in a critical condition.

There is currently no evidence to suggest that following a keto diet could help a healthy person prevent or treat infection with SARS-CoV-2.

However, there is evidence to suggest that keto diets can expose people to certain health risks — such as by raising cholesterol levels. Keto diets may also have side effects, such as flu-like symptoms, headaches, nausea, and changes in blood pressure.

There are also claims suggesting that various herbal medicines might be able to fight off the new coronavirus.

This may partly be based on a statement issued by a Chinese official in April 2020, suggesting that certain herbal drugs could help treat COVID-19, as a communication in The Lancet on May 15, 2020, reports.

Author Yichang Yang — from the Department of Traditional Chinese Medicine at the Second Affiliated Hospital of Zhejiang University School of Medicine in Hangzhou, China — warns that people should take encouragements to use herbal remedies in the treatment of COVID-19 with a pinch of salt.

Yang warns that herbal remedies — including the drugs that the Chinese official names — can have unexpected risks and may not be as effective as some people claim. Also, evidence from human trials is very limited.

For similar reasons, he also notes that the mechanisms through which herbal drugs work on the body are often unclear, which may mean that they are not always safe.

A mystery “herbal cure” for COVID-19 on sale in Madagascar — a herbal tea made from artemisia plants — has also spurred worry among specialists, who say that the “remedy” may do more harm than good.

Matshidiso Moeti, director of WHO Africa, has also commented on this:

“We [the WHO] would caution and advise countries against adopting a product that has not been taken through tests to see its efficacy.”

Although people may be tempted to try anything and everything in the face of such a threat to health as SARS-CoV-2, the most important preventive step is to follow official national and international guidelines for public health, as well as individual health advice from doctors and other healthcare professionals.

For more information on the new coronavirus and how to stay safe during the pandemic, take a look at the information from the Centers for Disease Control and Prevention (CDC) and the WHO.

For live updates on the latest developments regarding the novel coronavirus and COVID-19, click here.