What We Know About Vitamin D and Covid-19

Why we still don’t know whether a vitamin D supplement helps for coronavirus

Gideon M-K; Health Nerd
Medium Coronavirus Blog
7 min readOct 1, 2020


Pictured: More of a mystery than you might imagine. Source: Unsplash

We all want a miracle cure. We want a silver bullet, a single source of salvation that can save us from everything. This isn’t news, or particularly surprising, but it’s amazing how much this desire permeates everything we say and do when it comes not just to COVID-19, but to every aspect of our lives. It would be so much simpler if there was one cure that could fix everything.

Unfortunately, there almost never is. But that doesn’t stop us from wanting one.

Pictured: A wall full of hope, with very little promise. Source: Unsplash

But while this is true of every aspect of our lives, it’s so astonishingly true for COVID-19. From hydroxychloroquine to ivermectin, this year has been filled with nothing but miracle cure after miracle cure, and thus far they’ve all failed*.

Which brings us to vitamin D.

I’ve written before about the hazy promise of vitamin D for COVID-19, months ago, and how way back in early May the evidence just wasn’t there to recommend supplementation for COVID-19. Usually, updating this sort of analysis after such a short space of time would be a bit of a waste, but it turns out that during 2020 evidence moves so fast that even a week or two is enough for a deluge of new data to swamp what came before.

And yet, despite literally hundreds of new studies on the topic since my last article, the message that I have today is almost identical.

If we ask the question “Does vitamin D prevent/treat COVID-19?” the only real answer is “How could you possibly know?”

Sensationalist Science

A recent study on vitamin D and COVID-19 is a brilliant example of this. Hyped in the news and on social media as definitive evidence that we should all be supplementing our vitamin D levels, the study was a simple retrospective epidemiological paper looking at a small group of people who were hospitalized with COVID-19. The authors found that people who had lower vitamin D levels were more likely to experience some negative…