Nope, Vitamin D Does Not Prevent COVID

It really is becoming hard to remember just how we were clutching at straws to cope with the pandemic two years ago when all we had to prevent COVID was social distance and masks. No vaccines or Paxlovid. One of the straws we were clutching then was vitamin D. Both our ex-President and Tony Fauci were taking it. Might help, can’t hurt seemed to be the rationale. Well, the might help part of that rationale just fell apart with two new studies published yesterday in The BMJ. Both of these randomized, controlled studies showed that vitamin D supplementation will indeed not prevent COVID-19.

Test and Treat?

The first of these two trials was was a randomized controlled study of testing and treating people for low vitamin D levels. The object was to see if the test and treat strategy would prevent any respiratory infections and also if it would prevent COVID infections. It was large, with 6,200 persons randomized between two test and treat groups and a control group. In low-dose group, people who had low vitamin D levels received an 800 IU daily supplement. The high-dose group got a 3,200 IU supplement. Finally, the control group received no testing or supplementation.

The bottom line will surely disappoint the Vitamin D fan club. Neither high dose nor low dose vitamin D supplements did anything to prevent respiratory infections generally or to prevent COVID specifically.

Cod Liver Oil Vitamin D Supplement?

The second of this pair of studies was a huge blinded, randomized, randomized, and controlled study of giving 400 IU of vitamin D daily in the form of a cod liver oil supplement. There was no testing in this study of 34,601 adults, just a one-to-one randomization between the daily supplement or a placebo for up to six months. Norway was the setting for this study in late 2020 and early 2021.

This study had four co-primary endpoints, but there was no effect of the supplement on any of them. It neither reduced incidence of a positive COVID test, nor of serious COVID-19 infections. Furthermore it did nothing to change the numbers of people with negative COVID test results or self-reported respiratory infections that were not COVID. Nothing.

Not the Final Word

Even with these null results, people will be slow to give up their vitamin D supplements. In an editorial alongside these new studies, professor Peter Bergman offers perspective:

“Vaccination is still the most effective way to protect people from COVID-19, and vitamin D and cod liver oil supplementation should not be offered to healthy people with normal vitamin D levels. Importantly, these new trials remain compatible with the two large meta-analyses (here and here) suggesting that vitamin D supplementation may be beneficial for vitamin D deficient individuals.

“A pragmatic approach for the clinician could be to focus on risk groups; those who could be tested before supplementation, including people with dark skin, or skin that is rarely exposed to the sun; pregnant women; and elderly people with chronic diseases. For those with inadequate vitamin D levels (<50 nmol/L), supplementation with 1000-2000 IU/day could be a safe, simple, and affordable way to restore vitamin D levels, improve bone health, and take advantage of any possible protective effect against respiratory tract infections.”

At times, some of the benefits associated with vitamin D supplementation sound like magical thinking. These new data remind us to be skeptical about such speculation.

Click here, here, and here for the new studies and the editorial that goes with them. For further reporting, click here.

Nope, photograph © Ted Kyle

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September 8, 2022

3 Responses to “Nope, Vitamin D Does Not Prevent COVID”

  1. September 08, 2022 at 6:36 am, Al Lewis said:

    Vitamin D is the most overhyped vitamin since Vitamin E and Vitamin C before that. Unless you have a significant deficiency, supplements are worthless.

  2. September 08, 2022 at 9:36 am, Allen Browne said:

    As the detective said in Dragnet “ Just the facts, M’am”


  3. September 08, 2022 at 2:11 pm, Andrew Brown said:

    I love the photo attribution: “Nope, photograph © Ted Kyle” 🙂