Assaying vitamin D levels doesn’t necessarily mean that Vitamin D levels are the primary effector, though. Maybe I’m missing some details from the actual study, but showing that mortality risk is higher with a deficiency could support either of these:
1) Vitamin D deficiency causes increased mortality
2) Whatever causes increased mortality also changes or is correlated with Vitamin D levels
While you’re not wrong. I often see comments like this when new studies come out.
I think most people here know that correlation doesn’t mean causality. However in the case of Vitamin D, there’s a lot of studies pointing towards Vitamin D actually helping fight bad outcomes. Such as the clinical trial from Spain where they gave supplement Vitamin D to one group and compared the outcomes [0] That does seem to indicate that the Vitamin D really is helping.
If you look at the other comments on this thread, you'll quickly see why people like myself write comments clearly explaining what studies actually show. There is nothing wrong with understanding that the knowledge we have today is limited to a set of possible states - further study, such as the link, help collapse those states. Honestly, it makes the narrative more compelling too as showing direct action is easier than disproving all unseen movers.
Only read the article, which could be very different from the actual study, the Forbes article is referring to people already hospitalized so we are talking about a pretty low bar of health already (low but probably common, make note of that reality), and of those people they are "getting" Vitamin D, which kind of suggests after they are hospitalized.
This is new data then, because earlier studies were saying that Vitamin D supplements weren't improving circumstances, which would reinforce your perspective that people with inadequate Vitamin D levels had other issues.
This article doesn't specify what "getting" Vitamin D means, maybe the study does.
> After adjusting for confounding factors, there was a significant association between vitamin D sufficiency and reduction in clinical severity, inpatient mortality serum levels of C-reactive protein (CRP) and an increase in lymphocyte percentage
Here's the key sentence from the study results. They are claiming a significant association [0] between Vitamin D above and below a threshold [1] and clinical severity [2]. The word "getting" is a bit deceptive, because "getting enough" tends to be in reference to their base behavior. Eating fruit helps me get enough vitamin C, so a doctor might recommend adjusting my behavior if tests show I have vitamin C deficiency. Adjusting my behavior would hopefully result in me "getting enough".
This is pretty different when compared to the study showing treatment results from Spain (Per another commenter) [3]. Here's the key conclusions from that study:
> Our pilot study demonstrated that administration of a high dose of Calcifediol or 25-hydroxyvitamin D, a main metabolite of vitamin D endocrine system, significantly reduced the need for ICU treatment of patients requiring hospitalization due to proven COVID-19. Calcifediol seems to be able to reduce severity of the disease, but larger trials with groups properly matched will be required to show a definitive answer.
Treatment (Administration) with a chemical known to modulate the Vitamin D system now shows a clinical effect (ICU treatment reduction, albeit they have some reservations about study size). There's a whole set of further study that would need to be done to directly prove that the mechanism of action is exactly what they think it is, but it provides another good checkpoint (And is at the right abstraction layer to start considering it as a treatment more generally).
[0] Correlated, with the implication it could be worth studying as a causative driver
[1] "Sufficiency" is just a way of saying the assayed value is at least a value determined to be healthy
[2] They've got a long list of different clinical conditions they saw in the two cohorts
This is interesting to me. I know C-reactive protein is an important biomarker of inflammation, but I've never seen anything that indicates lowering CRP actually does anything. What I have seen is that interventions like exercise and statins lower CRP, and improve other markets of cardiovascular health.
One other interesting tidbit is this study [0], which suggests that vitamin D levels are inversely correlated with CRP levels, independently of COVID-19. This suggests to me that maybe the observed lower CRP levels in the COVID-19 patients might be a red herring.
#1 is technically right and how the story is usually presented.
#2 is also right! Measuring Vitamin D is kinda like measuring how many bullets someone has while fighting a war. Of course it's going to be low. But the soldier starting off with fewer bullets is still at a huge disadvantage.
This misses the point of the post, it isn't about presentation but what research was actually done. If the story had presented either of those as a summary of the study, it would have been wrong as the study did not interrogate whether either of those were correct. The study saw a relation, it did not discern how that relation was constructed or if clinical intervention along those lines would be useful.
Yes, low vitamin D is an indicator of frailty, so surely not all of the observed difference is causal. OTOH, giving people vitamin D in a RCT does seem to improve outcomes, so it looks like there's something real here.
1) Vitamin D deficiency causes increased mortality
2) Whatever causes increased mortality also changes or is correlated with Vitamin D levels