Does Vitamin D Protect Against the Coronavirus?

Fact-checking circulating advice

Photo: Marc Schmerbeck/EyeEm/Getty Images

Former CDC Director Tom Frieden, MD, published an opinion piece on Fox News this week that suggested taking vitamin D supplements could help boost the immune system, an essential piece of the puzzle in terms of how serious Covid-19 can be.

Vitamins are critical to keeping the body, especially the immune system, healthy. If you are vitamin deficient, it is a good idea to take a supplement; however, very few people in the United States actually are deficient. The one notable exception may be vitamin D.

By some estimates, nearly half of Americans are low in vitamin D, which humans synthesize from UV light. Now that most of us are sheltering in place, we’re probably getting even less vitamin D from sun exposure than before, so in theory taking a vitamin D supplement makes sense. In his article, Frieden cites a 2017 meta-analysis that reported people who took daily or weekly vitamin D reduced their risk of developing a respiratory tract infection. However, the benefit was only found in people who were vitamin D deficient; if people were not deficient, there was no effect. It’s also important to note that there has been no research on vitamin D and Covid-19, specifically.

“Big picture, there are a bunch of vitamins that, when people are in a state of deficiency, it will weaken the immune system, and increasing those vitamin levels will help,” says Pieter Cohen, an associate professor of medicine at Harvard Medical School. “For healthy people who are already taking care of themselves and are now wondering what else they can do to prevent coronavirus, increasing vitamin levels probably is not the way to go.”

Verdict: If you’re worried about your vitamin D levels or have been told by a doctor you’re deficient, go ahead and take a supplement. But please don’t go to your doctor asking for a vitamin level test now. Remain obsessive about hand-washing and adhere to social distancing.

Health and science writer • PhD in 🧠 • Words in Scientific American, STAT, The Atlantic, The Guardian • Award-winning Covid-19 coverage for Elemental

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