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Comment by edejong | Hacker News Reader

Talking about Vitamin D and calcifediol: why are we not informed that Calcifediol treatment (and as such Vitamin D supplementation) significantly reduces the chance of ICU admission and mortality in COVID-19 based on RCTs [1,2]?

[1] https://pubmed.ncbi.nlm.nih.gov/34097036/

[2] https://www.sciencedirect.com/science/article/pii/S096007602...

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> why are we not informed

What do you mean? I've been bombarded with Vitamin D recommendations since COVID started, from my doctor through countless podcasts. It also comes up frequently in any online discussion about COVID. And before anyone suggests otherwise, yes, Dr. Fauci has also spoken about Vitamin D.

But Vitamin D isn't a magic bullet. It helps, but it's not a miracle cure like some of the internet articles or early ad-hoc studies would imply.

The official NIH treatment guidelines contain no recommendation for vitamin D testing or supplementation. They were last updated in April 2021 and appear to not incorporate the latest research. At a minimum we ought to be testing vitamin D levels for many COVID-19 patients in order to identify those at greater risk of developing severe symptoms.

https://www.covid19treatmentguidelines.nih.gov/therapies/sup...

https://vitamin-d-covid.shotwell.ca/

Yeah, people have been talking about the decreased Vitamin D levels in COVID patients and suggesting supplementation since almost the very beginning of the pandemic. Maybe they just don't want to draw attention away from the fact that vaccination and masking are still by far the best means of avoiding hospitalization.

iirc, the first mention I remember was from a Stanford, CA area Doctor who was not waiting for the CDC to make a press release before making a statement about what he saw anecdotally (~Nov 2019) given how quickly his hospital was overwhelmed. Specifically, he noted that patients with Vitamin D deficiencies were having the worst symptoms.

Podcasts, Twitter, Youtube, Fauci (informally): yes. Official medical recommendations: none that I am aware of.

Because at least for Vitamin D in general, there are a bunch of studies, and overall it looks like it probably doesn't work[0].

I'd recommend taking it anyway, but there are more than two studies and the results are not solidly on the side of "it works".

[0] https://astralcodexten.substack.com/p/covidvitamin-d-much-mo...

I would like to take time to debunk that whole article, but let's just focus on the article [1] I shared and to debunk his argumentation for the preprint article [2].

To begin with, you have to understand that the vitamin D3 supplement we take is usually cholecalciferol, which is metabolised by our body over a period of weeks into calcifediol. The key takeaway is that the usual supplement takes weeks to be effective.

The RCT in article [1] is so strong because it supplements calcifediol at hospital intake, meaning the supplementation is immediately effective. So you can see that as a proxy for having supplemented with normal vitamin D for a couple of weeks prior.

In article [2], the one he is promoting, cholecalciferol (normal vitamin D) is supplemented. This means it is unlikely that it will have a significant effect during the first weeks of admission.

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7456194/

[2] https://www.medrxiv.org/content/10.1101/2020.11.16.20232397v...

That article is badly outdated and incomplete. I recommend reading through this more comprehensive list of studies.

https://vitamin-d-covid.shotwell.ca/

Maintaining adequate vitamin D levels probably does "work" in the sense of reducing the risk of severe symptoms. It is not a magic cure and shouldn't be relied upon as an alternative to vaccines or other therapies.

Most of these studies suck. For example, as mentioned in this response, https://academic.oup.com/jcem/article/106/12/e5271/6348963, to that first linked study (which may apply equally to the second, as it was just a trial for the subsequent study):

> However, the authors did not provide information on 25OHD serum levels after the supplementation, limiting the evidence of a causal link between vitamin D supplementation and the observed clinical outcomes.

IIRC, there was a similar study to the above that was retracted, in fact. Possibly even #2 above?

It’s an RCT. What will those measurements contribute? In addition, it is likely the measured serum levels will be lower because they are used up.

The first linked study was an observational cohort study, not an RCT. The second cited study was an earlier related pilot RCT by some of the same authors.

Here's a recent summary looking at both those papers and many others. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8787834/ TL;DR--it's all just too inconclusive at this point. Though as always everybody remains enthusiastic, notwithstanding that vitamin D papers have been perennial favorites long before COVID, without much to show for it.

FWIW, I think this is the retracted paper I had in mind earlier: https://retractionwatch.com/2021/02/19/widely-shared-vitamin... Somewhat similar design and at least one of the same authors. Retracted because it wasn't actually as randomized as claimed.

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