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News Article

Vitamin D and COVID-19

No firm evidence yet...

The debate around whether vitamin D could help treat or prevent COVID-19 is still unresolved. Recent preprint papers reported in the media suggest supplements may provide no benefit. There is a need for some gold standard randomised controlled trials to be conducted and published before this can be settled one way or the other. Official guidance continues to stress the need to avoid vitamin D deficiency for general health reasons but doesn’t advocate taking a supplement to prevent disease.

Over the last year there has been many papers suggesting that vitamin D could prevent or reduce severity of COVID-19. The vitamin has been shown to play a role in immunity against infection and in cytokine production. There is possible evidence (Jolliffe and colleagues, awaiting peer review) that it could prevent other viral infections.


Whats the latest?

Recently the Guardian newspaper reported 2 more non peer reviewed studies that suggested vitamin D supplementation may not help prevent or treat COVID-19 infection. The first study studied the association between outcomes from COVID-19 and genes that raise vitamin D metabolite levels in the blood. The second examined the relationship between population vitamin D deficiency and COVID mortality in 24 European countries.

These studies may in time, help clarify the role of vitamin D in COVID-19 but as the preprint server on which they sit, points out “They should not be relied on to guide clinical practice or health-related behaviour and should not be reported in news media as established information.” We need to wait until the peer review process is complete.  

Meanwhile  a third study published in JAMA Network Open last week provides more evidence of the association between vitamin D levels in the blood and risk of disease. It found that having vitamin D levels below 40 ng/ml within the last year was associated with increased risk of a positive COVID test among Black individuals but not among Whites. However, finding an association does not prove that an intervention would work. Randomised controlled trials  with Vitamin D supplements are needed to prove that.


Clinical guidelines and evidence reviews

There is very little good quality peer reviewed evidence one way or the other at the moment for the effectiveness of vitamin D for treating and preventing COVID-19. Clinical guidelines published by NICE in December were based on an evidence review in which just one study of treatment met the criteria for inclusion and there were no studies on prevention that met the criteria for inclusion.

In the light of that, it is not surprising that the formal clinical guidelines in the US and UK do not endorse vitamin D supplements  for COVID-19 and say more evidence is needed.

The guidance from NICE however, stresses that people should be following government advice to take vitamin D supplements through the winter months or all year round if they are not exposed to much sunlight outdoors. The recommended amount is 400 units daily (10 micrograms).

NICE’s evidence review also considered whether vitamin D was associated with COVID-19 susceptibility and severity. It found 12 studies that met the inclusion criteria but the evidence was low quality and not conclusive with some studies finding an association and some not.

It seems sensible to avoid vitamin D deficiency as NICE recommends, but it seems the evidence for people to take supplements to stop COVID-19 isn’t there yet.


In the pipeline

There are some studies in progress now that could help build more evidence alongside the studies reported last week that await peer review.

·         Annweiler and colleagues have published a protocol for a randomised controlled trial which is in progress now. 10.1186/s13063-020-04928-5.

·         Wang and colleagues from Harvard University also recently published a protocol.

·         Queen Mary University of London also has a planned trial in progress due to finish in June registered on clinical


More studies on vitamin D and COVID-19 in progress can be found at

Article details

  • Author(s)
  • I. Hoskins
  • Date
  • 19 March 2021
  • Subject(s)
  • Nutrition & disease