Research is exploring connections between vitamin D and the coronavirus. Before you go and stock up on vitamins, here's what you need to know.

Jessica Ball, MS RD
Updated November 05, 2020
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Vitamin D plays an important role in our health, and now new preliminary research suggests it may have a role in fighting COVID-19. A recent study in the Journal of Clinical Endocrinology & Metabolism found that over 80% of 200 COVID-19 patients at a hospital in Spain had vitamin D deficiency, with men having higher rates of deficiency than women. Another study conducted at Northwestern University collected data from 10 countries that were significantly affected by the coronavirus, including China, Italy, Spain and South Korea, and found a correlation between vitamin D deficiency and severity of COVID-19, as well as mortality rates associated with the virus. Other studies have connected sufficient vitamin D levels to better COVID-19 survival rates for hospitalized elderly people, with those who are deficient being at almost double the risk.

More than 1 in 3 American adults have insufficient levels of vitamin D. It can be difficult to consistently meet the daily recommendation of 15 micrograms through food, especially if you live in a northern state that experiences winter. So does this mean we should all start stocking up on vitamin D supplements and cod liver oil? Not necessarily. We dove into what the science says to learn more.

The science connecting low vitamin D levels and coronavirus mortality

Scientists have found that people with low levels of vitamin D had disproportionately higher mortality rates from the coronavirus, even when they controlled for age, health care quality and testing rates. Why do they think that is? Well, vitamin D plays a role in several body functions, like keeping your bones, heart and mind healthy, plus it strengthens and regulates the immune system. When someone is deficient in vitamin D, that means less regulation, which can lead immune cells (also called cytokines) to overreact. If that same person contracts COVID-19, their immune system may overreact—what researchers call a "cytokine storm"—and possibly lead to severe damage to the lungs, acute respiratory distress syndrome and even death.

Recent research suggests that sufficient levels of vitamin D can support a healthy immune system and might help prevent it from becoming overactive. This could also explain why children are considered to have a relatively low risk of complications from the virus, since their immune systems are not totally developed to trigger this response. More studies are needed to clarify the interactions between vitamin D and COVID-19, including direct measurement of vitamin D levels in subjects.

Should I take a supplement?

This research doesn't mean everyone should start taking vitamin D supplements. However, it does mean that being deficient in vitamin D might put you at a greater risk of complications if you contract COVID-19. This may be especially important for populations, like older adults and African Americans, who are more prone to vitamin D deficiency and anyone considered in the high-risk group for COVID-19 complications.

Vitamin D can be found in many forms aside from supplements. Food sources of vitamin D include salmon, mushrooms, fortified milk (and fortified dairy alternatives), sardines, eggs, tuna and cheese. Just 3 ounces of cooked salmon can provide 71% of the daily recommended amount. Vitamin D comes mostly from animal sources, so people who follow vegetarian or vegan diets may need to be more diligent about meeting their needs through fortified foods. Your body can also produce vitamin D from the sun, but the National Institutes of Health warns that although we can meet some of our D needs this way, skin cancer prevention should be top of mind when considering sun exposure. It's also harder to make vitamin D from the sun in winter months.

If your climate makes it challenging to get outside in the sun regularly or you are concerned about your intake from food, a supplement can be helpful to meet the daily recommended amount of vitamin D. It's likely supplementing with vitamin D is a low-risk way to help protect yourself. Dr. Fauci recommends taking a vitamin D and a vitamin C supplement to help support a healthy immune system and ensure you are meeting your needs. If you're exploring taking a supplement, the best thing to do is talk to your doctor first, since they will know a little bit more about your health history and can also request a vitamin D test. (Learn more about how to keep your immune system healthy.)

Bottom Line

We know that vitamin D can help support a healthy immune system, which may be particularly helpful against the coronavirus. While it does not cure people who have contracted the virus and there is no magic amount you should take, getting enough vitamin D can keep you and your immune system healthy. Because many Americans are deficient, it's important to try to get plenty of vitamin D from food and from some time outside in the sunshine (so long as you are being safe during your outdoor time). If you are concerned you might have a deficiency, talk to your doctor to learn more about your options and if supplementation is right for you.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While EatingWell is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.