2/ Let's start with 2 summaries. All sources at the end.
๐ง๐;๐๐ฅ #๐ญ - For most people, it's safe to take anywhere from 200 to 4000iu of Vit D/day.
We just don't want ppl to think these pills are an alternative to social distancing,๐ท, or medical help if you're sick. E.g. โฌ๏ธ
3/ ๐ง๐;๐๐ฅ #๐ฎ - There's a TON of uncertainty w/ #VitaminD.
๐จ) Weโre not totally sure what Vit D level people need
๐ฉ) Weโre not sure if levels behave like a phase reactant
๐ช) We're not great at measuring levels
๐ซ) Weโre not sure how much supplements help
4/ But there's a lot we do know too:
- It's safe to take for the majority of ppl (I'd be more cautious w/ ppl w/ hypercalcemia or ++renal disease)
- It's involved in the immune system and major deficiency is a problem
- Vit D supplementation is a huge and profitable industry
5/A - When it comes to Vit D levels, we have shockingly little good outcomes data. We can't even really agree what a good level is (quick example below).
And outside of major deficiency and older โ๏ธ w/ osteoporosis, we can't really say "A level of X-Yโฌ๏ธthe risk of [bad thing]"
6/A - ^Why so little confidence? B/c aside from the lack of studies, there's SO. MANY. CONFOUNDERS.
Chronic illness, hospitalization, sedentary lifestyle, etc. can all reduce Vit D levels. They also โฌ๏ธrisks for lots of other issues.
It becomes a correlation โ causation thing.
7/B - This brings us to the next fun bit: Vit D levels might be a
It means levels might "shift" in response to inflammation w/out you suddenly becoming deficient.
8/B - The mechanisms behind APPs are cool af.
One APP is Ferritin (iron storage molecule).
It's one of the things we measure when assessing iron levels.
Ferritin is a *positive* APP. If you've got systemic inflammation, ferritin levels can๐ SKYROCKET ๐ from like 150 to 500+
9/B - When that happens, we don't assume you suddenly got baller Iron levels ๐ฐ๐๐ฐ
We just realize it's a phase reactant. Your body "hides" iron in storage when there's inflammation. It normalizes afterwards.
It's also why we don't usually do Iron panels on +++sick ppl.
10/B - There have been studies suggesting Vit D is a *negative* APP for a while.
- Pts with post-op illness/inflammation will have levels suddenly tank.
- Same w/ septic pts.
- In other cases it might have an inverse relationship to CRP (an inflammatory biomarker).
11/B - We need +data here, but it could certainly help describe a very annoying pattern we keep seeing:
1) Study comes out correlating Vit D deficiency w/ X
2) Studies attempt to prevent or correct X w/ supplementation and fail (e.g. MS, cognition, asthma, etc) ๐
12/C - Did I mention levels can be super unreliable even when stable?
Our measurements can vary by an avg of 30-40% or more
Personal story - One of my earliest "good job" moments was asking for a rpt Vit D level in a pt w/ hyperCa.
1st level: 135 - ๐คทโโ๏ธ
2nd: 225!
12/C - This has major implications too.
For example, improved tech in Vit D measurement changed the recommended dietary allowance from 800 to 400 iu (in osteoporosis) in the US Endocrine society in 2017.
13/D - Jesus it took a while to get to the COVID part, didn't it?
And I'm gonna outsource most of that work anyway ๐
But here's the deal - I would LOVE for Vit D to be a viable treatment. And I'm a big believer in not letting the perfect be the enemy of the good...
14/D - But most of the current Vit D treatment studies have MAJOR issues. No study is perfect, but just look at @fperrywilson's great analysis of the new study making the rounds.
15/D - Like, even if we put aside their other major flaws, who tf submits a COVID clinical trial to the LANCET without even baseline severity data for their pts?
To me, that's the equivalent of trying to sue states to overturn an elections.
It's for show. ๐บ
16/D - This has been a recurrent issues. Another Vit D study (Castillo et al) that made waves earlier actually posted that baseline data just look at it ๐ซ
17/D - So we get all this super low quality data, with some slightly better looking studies like the one from Brazil being negative.
18/D - Now, there are lots of very smart people very different opinions on this right now.
I'd encourage you to check out this discussion from @PaulSaxMD :
When pts ask me why I'm skeptical of #supplements by default, I give examples to highlight the lack of regulation+data. I wrote some here.
Title: โSome reasons I'm cautious with supplements and would rather you get the nutrients in your diet"
Rolls off the tongue, I know.๐งต
1) The largest trials of antioxidant ๐showed they donโt โฌ๏ธrisk of cardiovasc events, diabetes, cancer, or cognitive decline.
Some showed โฌ๏ธhemorrhagic stroke and prostate cancer, but itโs inconsistent.
2) Vitamin C pills failed to โฌ๏ธ the risk of getting a cold in trials of the general population. Starting it AFTER you get a cold doesnโt seem to help.
But if you take it regularly and get a cold, it might be 8% shorter ๐