Exactly this. Vitamin D level is a proxy for general health. Studies that have controlled for other factors affecting health have not found a protective effect from vitamin D [1].
Hacker News is obsessed with vitamin D because it seems like a hack. A cheap and simple way to solve a tough problem that you can feel smart about having found.
The control group spent on average 36 days in the hospital, the group getting a single 500,000 IU dose of vitamin D3 spent an average of 18 days in the hospital.
This study isn't correlation, it was a double blind randomized control trial. However, it was a small pilot study and more research is needed.
The fact that this was based on only 31 people, showed a marginal effect (barely passed even the lenient p < 0.05 threshold) and doesn't seem to have been replicated in a bigger study despite being published 4 years ago should make you very sceptical about it. Sure, more research would be good, but nobody should be making any decisions based on this.
It’s rather poor form to link a 60 page report without specifying which section supports your argument. I skimmed it and didn’t see what you said, and the summary recommends vitamin d supplementation in general.
Further, this spanish RCT suggests vitamin D had incredibly strong effects in preventing patients from needing to go to the ICU.
That isn't what that paper says. From "limitations of the evidence":
>All 5 studies were assessed as being at high risk of bias
What is not here is any study controlling for the factors you mention and finding a zero correlation as you claim.
The conclusion, which I assume you are referring to, states:
>There is no evidence to support taking vitamin D supplements to specifically prevent or treat COVID-19. However, all people should continue to follow UK Government advice on daily vitamin D supplementation to maintain bone and muscle health during the COVID-19 pandemic.
Since vitamin D supplements are already advised for the general population, it is extremely unlikely they would be recommended for specifically COVID-19 without very high-quality evidence. Unless dosing recommendations can be given with good reason to believe those recommendations would be beneficial, the only effect that could come of a positive conclusion is risk compensation, i.e. increased risky behaviors, which is bad.
I am only one data point, but from my experience, it really is a hack. I had super crazy migranes, was always tired and felt unmotived. Then I started supplementing Vitamin D and now I feel so energetic, it is kind of scary.
There have been a lot of studies done on vitamin D supplements, and there is essentially no significant evidence that supplementation is useful for anything. The sole exception is rickets, which is caused by vitamin D deficiency.
There is also considerable debate over the comparative efficiency & effects of natural synthesis via sunlight vs ingesting supplements, compounded by the difficulty of accounting for things like exercising outdoors vs being sedentary indoors.
Annecdotal: I live in a fairly northern country, and I've heard quite a lot of people say their mood is more normal over winter if they supplement with Vitamin D.
I don't have any strong opinion one way or another on the efficacy of vitamin D. But people who say they feel better after taking it may themselves be experiencing a placebo effect. Placebo effects are real, and they can improve both mood and health. The mind is an amazing thing.
People in the UK are unable to get enough vitamin D if they spend lots of time outside from around now until March (equinox to equinox) next year because of the high latitude. The sun is too far low on the horizon.
Most of Canada and Alaska is lower in latitude than the UK.
Note that Vitamin D hangs around in your fat for a month or two anyhow.
Part of my family lives in Italy and we may have a genetic trait, because many suffer from vitamin D deficiency even those young and "living outside". Old members have classic consequences: osteoporosis.
Could it also be that vitamin D levels indicates some other pathology and maybe supplementation with vitamin D itself doesn't do anything for chances of getting infected?
(We are more speaking about servility of symptoms then becoming infected.)
But yes, it could totally be the case.
It also might not be the case.
It also might be anywhere in-between, like supplements help but the a negligible degree.
As long as we don't have statistically significant studies showing causation we can't say for sure.
But then what we can say for sure is that any deficit puts a burden on you body and any burden makes it harder for you if you get some other massive health problems. Even if just to a very small degree.
So if you have a vitamin D deficit you should fix it especially if you also have COVID (EDIT: or any potentially more dangerous illness).
But if you don't have a deficit it's questionable if taking vitamin D will do any help.
Well, yes Vitamin D does attenuate immune response. However the science on citokine storms is most probably wrong and not associated with covid, and at this point has become hard to stop the information train on. If there's one thing I've learned about people during covid is that the game of telephone played over a short time period to get something solved is a huge issue.
