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Vitamins Supplements and COVID-19

Vitamin C, vitamin D, zinc, and elderberry are a few of the vitamins and supplements making headlines lately as researchers begin to study their possible role in the prevention and treatment of COVID-19 and anecdotal reports circulate social media.

“These are all compounds with a known role in immune function, but none are yet proven to benefit in the prevention or treatment of COVID-19, the illness caused by SARS-Cov-2,” says Susan M. Goodman, MD, a rheumatologist at Hospital for Special Surgery in New York City.

We asked experts to explain what’s behind these claims — including what we know and don’t know — and what people with arthritis and rheumatic disease should consider prior to taking supplements during the COVID-19 pandemic.

The bottom-line message: No vitamin or supplement has been proven to prevent or treat COVID-19, nor can these replace social distancing, hand washing, wearing a mask, other public health guidance, or taking your disease-modifying medications as prescribed. Unfortunately, as most of us have learned, “the best methods to prevent COVID-19 are simple to understand, but challenging to perform over months and months,” says Dr. Goodman.

Vitamin D

It’s not too surprising that researchers are investigating a link between vitamin D and COVID-19. Vitamin D deficiency has long been linked to an increase in risk for respiratory tract infections.

Plus, many Americans who are deficient in this so-called “sunshine vitamin” are also among groups at higher risk for severe COVID-19, including the elderly and those with darker skin, diabetes, and obesity, as well people taking glucocorticoids, says Dr. Goodman.

Vitamin D is called the sunshine vitamin because your body can manufacture it after you’ve spent time in the sun, but many people require supplementation to get to optimal levels.

“Vitamin D helps resolve inflammation, which is how it regulates the immune system,” says Marhgerita T. Cantorna, PhD, a medical microbiologist and immunologist at Pennsylvania State University who studies the functions of vitamin D in immune cells. “Patients with COVID-19 have local and systemic inflammation later in the infection, so the idea is that vitamin D can help resolve inflammation,” she explains. “But it’s not known yet what vitamin D is doing to the virus.”

A recent study led by Northwestern University researchers found a link between vitamin D levels and cytokine storm — a hyperactive immune response that occurs in some people with COVID-19 — as well as a correlation between vitamin D deficiency and mortality. The researchers discovered that patients from countries with high COVID-19 mortality rates, including Italy, Spain, and the UK, had lower levels of vitamin D.

However, other research indicates that the link between vitamin D and COVID-19 is likely a correlation rather than a causation. Two recent studies using data from the U.K. Biobank, which tracked the health of a half million people, found that when results were adjusted for age, race, obesity, and socioeconomic status, participants who tested positive for the coronavirus were not found to be more likely to have low or deficient levels of vitamin D.

The second group found similar results: After analyzing nearly 600 participants who tested positive for coronavirus, they found that their vitamin D blood levels were “almost identical” to those who tested negative for the virus.

In other words, it may be the case that people who are at high risk for COVID-19 complications just happen to also have lower levels of vitamin D, rather than the low levels of vitamin D making them at an increased risk.

Vitamin D Dosage

Still, it can’t hurt to make sure you’re getting enough vitamin D each day, because the vitamin is also important for bone health and many people with rheumatic or autoimmune conditions seem to have low levels of it. Exactly how much vitamin D healthy adults should get has been debated, ranging from 200 IU per day to 2,000 IU per day, says Dr. Cantorna.

“Some studies suggest really high doses of vitamin D, and this worries me,” says Dr. Cantorna. “More is not better.” Taking too much vitamin D can lead to hypervitaminosis D, which is a serious condition that causes nausea and vomiting, weakness and frequent urination, bone pain, and possibly the formation of kidney stones.

Yet, she adds, you certainly won’t experience vitamin D toxicity from eating a diet rich in vitamin D (oily fish like mackerel, tuna, and sardines; mushrooms; and fortified dairy and non-dairy substitutes are good sources). And it can’t hurt to take a socially distanced walk and soak up some sun. Just 10 to 15 minutes outdoors without sunscreen can provide the body with a good amount of vitamin D. “Getting outside and enjoying the outdoors would also help with mood, and you might improve your vitamin D status even if you wear sunscreen,” says Dr. Cantorna.

Consider talking to your rheumatologist about getting your vitamin D levels checked periodically so you can decided together whether you need to take supplements, suggests rheumatologist Douglas Roberts, MD, assistant clinical professor of medicine at the University of California Davis Medical School and founder of PainSpot.org.

“Testing and supplementing those with low vitamin D levels is good standard practice,” agrees Dr. Goodman.

Vitamin C

You’ve likely heard about taking vitamin C to support your body’s natural defenses against the common cold (though the research there is modest). Now clinical trials are testing how high-dose vitamin C infusions may work against COVID-19.

A study published last year found lower death rates in patients with severe infections (though not COVID-19) who had sepsis and acute respiratory distress syndrome (ARDS) who were treated with vitamin C therapy. Sepsis and ARDS are common among those with severe COVID-19 infections.

For vitamin C, its potential role is linked to possible modulation of the marked inflammatory response to COVID-19, or ‘cytokine storm’ described in COVID-19 patients,” says Dr. Goodman.

Vitamin C (also known as L-ascorbic acid) is best known for its antioxidant properties. It helps protect the body from free radicals that damage and destroy otherwise healthy cells.

Yet it has numerous other important functions within the body, including those known to support healthy immune function.

“Vitamin C may play a role in damping down mediators of inflammation in the normal immune system, and the hypothesis is that it could lessen the impact of inflammation in COVID-19 patients,” notes Dr. Goodman.

While we don’t know whether vitamin C is effective at any dose for COVID-19, we do know that the megadoses being studied are not safe for you to take on your own. Too much vitamin C can lead to sleep troubles and unpleasant gastrointestinal effects (stomach pain, diarrhea, nausea) as well as hemochromatosis, which causes the body to store too much iron and damage body tissues.

Vitamin C Dosage

Healthy adults only need 75 mg to 90 mg of vitamin C a day, according to the National Institutes of Health. You can reach the recommended amount pretty easily by eating a diet rich in colorful fruits and vegetables. For example, one orange contains 75 mg, a cup of chopped raw red peppers has 195 mg, and one cup of cooked broccoli has 101 mg.


Zinc has been well-studied in its role in the common cold (with mixed results). Though some anecdotal reports are touting the supplement for antiviral effects, studies are underway to determine if these antiviral effects translate to the prevention and treatment of COVID-19.

When it comes to common colds and viruses, zinc lozenges are thought to work when taken within 24 hours of the onset of symptoms when infection is just starting to spread — and then stopped once the symptoms subside. The mineral inhibits virus activity in the throat, slightly lessening cold symptoms.

“There have also been links found between zinc deficiency [which is rare in North America] and an increased susceptibility to infection,” says Dr. Cantorna.

Zinc has a role in the normal immune system and in normal physiology, notes Dr. Goodman. “Those who are zinc deficient have higher levels of the same inflammatory mediators, or cytokines, that contribute to the cytokine storm in COVID-19 patients,” she says. However, “there are no studies that demonstrate zinc’s efficacy in preventing or treating COVID-19.”

Warns Dr. Roberts: “If you take too much zinc [for too long], you can get lower copper levels.” Excess zinc can also lead to lower levels of immunity and low levels of HDL (“good”) cholesterol.

Zinc Dosage

Healthy adults only need 8 mg to 11 mg of zinc a day, according to the National Institutes of Health (NIH). Oysters contain the most zinc, with 74 mg per one serving, but there’s also a variety of everyday foods you can incorporate in your diet to increase your zinc levels, including beans, nuts, whole grains, dairy products, and fortified cereals.

There is usually no need to take zinc supplements on a regular basis (a typical diet should give you adequate levels) but over-the-counter zinc lozenges can be taken at the onset of cold-like symptoms per the package instructions.


Studies have found that elderberry (in the form of teas, lozenges, gummies, or pills) can help people recover faster from the flu. Researchers attribute it to the antiviral properties of the dark, purple berry, which is thought to help stop the influenza virus from entering and replicating in human cells. Yet there is no data to suggest this will work in the same way for the coronavirus.

Importantly, if you have arthritis or rheumatic disease, it may be downright dangerous to experiment with elderberry. “We know that elderberry augments certain cytokines, like TNF and interleukin-1, but we don’t know if it reduces the effectiveness of your immunosuppressing medication,” says Dr. Roberts. “Most experts agree it’s not a good idea to take elderberry at any time if you’re taking immunosuppressants.”

The bottom line for now: Until we know more about COVID-19 and additional, more robust studies are conducted, there doesn’t seem to be a strong reason to take these (or any) supplements specifically to prevent and/or shorten the duration of COVID-19.

That doesn’t mean these supplements may not be helpful for other reasons — your doctor might recommend you take vitamin D to help your bone density, for example; vitamin C may have value as an anti-inflammatory supplement for people with arthritis.

That said, it’s always a good idea to talk to your doctor before taking any vitamins and/or supplements, as they can potentially interact with your medications. And don’t forget to focus on other important ways you can help your immune system function optimally, such as sleep, balanced nutrition, exercise, and stress management.

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Can vitamin C prevent a cold? Harvard Health Letter. January 2017. https://www.health.harvard.edu/cold-and-flu/can-vitamin-c-prevent-a-cold.

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Interview with Douglas Roberts, MD, rheumatologist and assistant clinical professor of medicine at the University of California Davis Medical School and founder of PainSpot.org.

Interview with Marhgerita T. Cantorna, PhD, a medical microbiologist and immunologist at Pennsylvania State University

Interview with Susan M. Goodman, MD, a rheumatologist at Hospital for Special Surgery in New York City

Kumar A, et al. Potential Role of Zinc Supplementation in Prophylaxis and Treatment of COVID-19. Medical Hypotheses. November 2020. doi: https://doi.org/10.1016/j.mehy.2020.109848.

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Porter RS, et al. A Review of the Antiviral Properties of Black Elder (Sambucus Nigra L.) Products. Phytotherapy Research. April 2017. doi: https://doi.org/10.1002/ptr.5782.

Singh S, et al. Assessing the Role of Zinc in COVID-19 Infections and Mortality: Is Zinc Deficiency a Risk Factor for COVID-19? MedRxIV: The Preprint Server for Health Sciences. June 14, 2020. doi: https://doi.org/10.1101/2020.06.12.20105676.

Torabian G, et al. Anti-influenza activity of elderberry (Sambucus nigra). Journal of Functional Foods. March 2019. Doi: https://doi.org/10.1016/j.jff.2019.01.031. 

Vitamin C. Office of Dietary Supplements. National Institutes of Health. https://ods.od.nih.gov/factsheets/VitaminC-Consumer.

Vitamin C Infusion for the Treatment of Severe 2019-nCoV Infected Pneumonia. ClinicalTrials.gov. U.S. National Library of Medicine. https://clinicaltrials.gov/ct2/show/NCT04264533.

Zinc. Office of Dietary Supplements. National Institutes of Health. https://ods.od.nih.gov/factsheets/Zinc-Consumer.

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