Also see this letter by Dr. Gerry Schwalfenberg. It's just an anecdote but his claim of success in treating influenza patients with a "vitamin D hammer" is interesting and should prompt additional research.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4463890/

Total anecdote, but I’m prescribed 50k IU of Vitamin D 3x weekly.

However, that’s a bit hard to remember so I always have extra on hand. When I have a cold coming on a take a large(r) dose and it certainly seems to help.

I haven't seen that one, that looks pretty impressive, especially for administering it in a single dose that is that large. That's definitely a good data point in favor that some of it is direct causation though.

31 total subjects, only 13 vitamin D deficient initially, p = 0.03. This study at best suggests further, more rigorous research here may be warranted. It says nothing about causation, for all that its authors seem to feel otherwise - and that they feel otherwise suggests its results should be taken with more than the usual amount of skepticism.

Have a look at table 1. Only 5/31 subjects had “sufficient” vitamin d. In between deficient and sufficient there is the insufficient category, from 20-30 ng/ml.

Though I agree further study is warranted. The highest vitamin D group actually had the highest mortality after 84 days. Though this group also had the most pre-existing heart conditions by far, so that could account for it.

Ah, there was a second such study in the pdf. Mortality down by almost half.

——————

Intervention was carried out intramuscularly with 300,000 IU of vitamin D. Instead of 28 days only 18 days mechanical ventilation, instead of 29 only 19 on ICU, instead of 61% deaths only 36%.

https://pubmed.ncbi.nlm.nih.gov/31531088/

More studies referenced here, also showing ~55 ng/ml being optimum for maximum health benefits. The current recommendations are way below that. Well worth to watch the whole video:

https://youtu.be/v3pK0dccQ38?t=4105

Those dosages are far higher than anyone supplementing vitamin d are likely to take.

I found out on HN that the official daily recommended dose for vitamin D is flawed, it was based on an erroneous statistical analysis. [1] contains some details. The bottom line is the daily dose should be about 8000 IU rather than the official 400 IU.

Obviously, 250000 IU or 500000 IU is much higher, but this is a one-shot, not a daily dose. If you take 8000 IU daily dose as correct, then those 2 megadoses correspond to a one month or two month intake. Very high indeed, but not absurd

[1] https://pubmed.ncbi.nlm.nih.gov/28768407/

When that came out a few years ago [1], I began getting my vitamin D tested through my doctor and slowly ramped up my dosage. It went from 28 ng/mL (70nmol/L) [2] to 32-35 ng/mL (80-87.5 nmol.L). In my own physiology, this required 4,000 IU (100 mcg) daily, orally. 2,000 IU was not quite enough.

I'm going to add another 2,000 IU daily to see if I can reach the recommended 100 nmol/L from the OP. [3]

[1] https://news.ycombinator.com/item?id=15867918

[2] converter here: https://www.azcalculator.com/calc/vitamin-d-ngml-nmolL-conve...

[3] https://pubmed.ncbi.nlm.nih.gov/28768407/

Now, there is a difference between "ramping up" levels and maintenance levels, right?

It's generally been found that larger doses are required to move the blood levels up, but it doesn't seem like people need to remain at those dosages to maintain those levels.

A few things.

Whenever your conclusion is that the "official recommendations are flawed", and those were in place for a while now, scrutinize your process. Reading a post on social media is rarely paradigm-changing - and when it is, it's overwhelmingly in the wrong direction.

Secondly, the 8k dose doesn't seem realistic historically. Is there any diet that does not include the products of modern tech, that gets anywhere near those levels consistently? Doesn't seem likely.

Megadoses of anything are not without issues. There will be side-effects with vit D, esp. related to calcium, etc.

The data on the possible connection between vit D and respiratory illness is still way more sketchy than most people assume. There is no solid research yet.

---

That being said:

Vit D deficiency is pervasive in a lot of places. Most people would benefit from taking some supplementation.

1000 UI capsules are cheap and readily available. That dose is not far from the various "official" recommendations (which are all over the range of the hundreds, depending on country). There are no known side-effects at that level.

> Secondly, the 8k dose doesn't seem realistic historically. Is there any diet that does not include the products of modern tech, that gets anywhere near those levels consistently? Doesn't seem likely.

Because historically most vitamin D intake didn't come from diet, but from sunlight exposure. Varying widely depending on how much skin you're exposing, the color of your skin, latitude, season, etc., estimates of vitamin D hourly vitamin D synthesis can be on the order of tens of thousands.

Diet wise no. Skin production wise, yes. Though these are different mechanisms and the body can turn off vitamin d production from the skin past a certain point.

They’re single use doses. These are often used by doctors to treat severe deficiency, e.g. weekly 50,000 UI.

It is plausible that in an ICU situation with limited time a single, even larger dose makes sense. For an individual not critically ill, more gradual daily boosting of vitamin D is possible. The ICU patients didn’t have this time.

What's the LD50 for vitamin D?

You experience issues with hypercalcemia long before the ld50 becomes an issue if you plan on supplementing too much

I'm thinking of a single megadose scenario.

Wow that could be a game changer. I’m surprised I hadn’t heard about that.