1/ Plenty of people like @deonandan and @DeNovo_Fatima have made great points on the #VitD buzz. Here's my 2 cents.

๐‘Šโ„Ž๐‘ฆ ๐‘Ž๐‘Ÿ๐‘’ ๐‘š๐‘œ๐‘ ๐‘ก ๐‘ ๐‘๐‘–๐‘’๐‘›๐‘ก๐‘–๐‘ ๐‘ก๐‘ /๐‘‘๐‘œ๐‘๐‘ก๐‘œ๐‘Ÿ๐‘  ๐‘ ๐‘ข๐‘โ„Ž ๐‘๐‘ข๐‘ง๐‘ง๐‘˜๐‘–๐‘™๐‘™๐‘  ๐‘Ž๐‘๐‘œ๐‘ข๐‘ก ๐‘‰๐‘–๐‘ก ๐ท ๐‘Ÿ๐‘–๐‘”โ„Ž๐‘ก ๐‘›๐‘œ๐‘ค?

Man I suck at titles.
2/ Let's start with 2 summaries. All sources at the end.

๐—ง๐—Ÿ;๐——๐—ฅ #๐Ÿญ - 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,๐Ÿ˜ท, or medical help if you're sick. E.g. โฌ‡๏ธ
3/ ๐—ง๐—Ÿ;๐——๐—ฅ #๐Ÿฎ - There's a TON of uncertainty w/ #VitaminD.

๐‘จ) Weโ€™re not totally sure what Vit D level people need

๐‘ฉ) Weโ€™re not sure if levels behave like a phase reactant

๐‘ช) We're not great at measuring levels

๐‘ซ) Weโ€™re 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†๏ธthe 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†๏ธrisks 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

๐ŸŒŸ ๐˜ผ๐˜พ๐™๐™๐™€ ๐™‹๐™ƒ๐˜ผ๐™Ž๐™€ ๐™๐™€๐˜ผ๐˜พ๐™๐˜ผ๐™‰๐™ ๐ŸŒŸ

๐˜ฐ๐˜ฐ๐˜ฐ๐˜ฐ๐˜ฉ.... ๐˜ข๐˜ข๐˜ข๐˜ข๐˜ฉ๐˜ฉ

WTF does that mean?

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 can๐Ÿš€ SKYROCKET ๐Ÿš€ from like 150 to 500+
9/B - When that happens, we don't assume you suddenly got baller Iron levels ๐Ÿ’ฐ๐Ÿ“ˆ๐Ÿ’ฐ

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) ๐Ÿ™ƒ
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 - ๐Ÿคทโ€โ™‚๏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 ๐Ÿ˜Ž

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. ๐Ÿ•บ
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 ๐Ÿ˜ซ
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 :

18/D - ^They talk about the Castillo study as well and bring up some good points (1 correction: it had 75pts, not 150)

My opinion is that you can't statistical-analysis yourself out of a tiny, heterogenous pilot study.

But I have the same end opinion: We need better studies.
19/ Wow that was a lot of work to end with such lame uncertainty.

Kinda like 99% of medicine.
Another great analysis of the study from a more in depth angle and featuring some... Interesting commentary from the authors.

โ€ข โ€ข โ€ข

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More from @TheAmirImani

1 Jan
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: โ€œSome reasons I'm cautious with supplements and would rather you get the nutrients in your diet"

Rolls off the tongue, I know.๐Ÿงต
1) The largest trials of antioxidant ๐Ÿ’Šshowed they donโ€™t โฌ‡๏ธrisk of cardiovasc events, diabetes, cancer, or cognitive decline.
Some showed โฌ†๏ธhemorrhagic stroke and prostate cancer, but itโ€™s 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 doesnโ€™t seem to help.
But if you take it regularly and get a cold, it might be 8% shorter ๐ŸŽ‰


Kids might be another story tho
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