[colossal]

It has shown to be correlated with better outcomes. It is also correlated with being healthier, being active, and eating better. As far as I understand there is no strong evidence for a causal relationship.

To be clear, if you live in the northern hemisphere, you should be taking vitamin D. It's cheap and at worst harmless. But that's not the same as saying it will improve the outcome of covid patients.

[ekianjo]

Not just that there is a clinical trial done in spain where giving vitamin D as metabolized clearly improved covid19 patient outcomes.

[mlyle]

IV calcifediol (Vitamin D) in early-stage COVID has improved outcomes in small randomized controlled trials.

Oral vitamin D has been shown to be ineffective at this point, but this isn't surprising: it takes a long time of sustained oral supplementation to raise levels.

Then there's a whole lot of evidence showing correlation, but as you point out, low vitamin D is an indicator of frailty. This is much weaker evidence.

I think it's likely that taking oral vitamin D before infection probably improves outcomes somewhat.

[travmatt]

I haven’t heard vitamin d administration is associated with better outcomes, but I’ve heard that vitamin d levels are inversely correlated with outcomes - i.e., people should take a blood test and determine if they are vitamin d deficient, and supplement as needed.

[mlyle]

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

> Of 50 patients treated with calcifediol, one required admission to the ICU (2%), while of 26 untreated patients, 13 required admission (50 %) p value X2 Fischer test p < 0.001.

Strengths: Randomized, very strong effect, strongly statistically significant.

Weaknesses: single trial, single center, relatively small sample, not blinded.

https://pmj.bmj.com/content/early/2020/11/12/postgradmedj-20...

> Greater proportion of vitamin D-deficient individuals with SARS-CoV-2 infection turned SARS-CoV-2 RNA negative with a significant decrease in fibrinogen on high-dose cholecalciferol supplementation.

Strengths: Randomized, blinded trial

Weaknesses: single trial, single center, relatively small sample, secondary outcome measure

[metiscus]

I will say, I've been regularly taking Vitamin D for a while and recently started having some low back pain. Talked to the doctor and was told to take some magnesium. Apparently it is used along with Vitamin D. So if you find yourself in my situation, talk to your doctor.

[Izkata]

> and at worst harmless.

Half true, you can take too much [0], it's just that it either has to build up over a long time or be from dosages far larger than you can buy without a prescription.

[0] https://www.healthline.com/nutrition/vitamin-d-side-effects

[lambdaba]

Vitamin D is key to T-cell function. T-cell immunity is involved in mild / asymptomatic covid cases (vs antibody immunity).