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Comment by dragonwriter | Hacker News Reader

> Mind you, what was previously (and mostly still is!) considered “high doses” of vitamim D are actually closer to the RDI than the doses anyone is taking. The RDI for vitamin D was miscalculated as 1/10th its proper value decades ago, and this error was only recently corrected:

No, there is a paper claiming that it was miscalculated and should be corrected (and, as another comment notes, there is a later paper calling for a reduction rather than an increase.) The actual current numbers remain (for most age groups):

Estimated Average Requirement: 400IU/day

Recommended Daily Allowance: 600IU/day

Tolerable Upper Intake Level: 4000IU/day

A paper calling for a change in the RDA is not a change in the RDA.

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What? There are doctors that are prescribing 2000IU+ daily. I have vitamin D supplements with 2000IU per pill.

I've read lately about multiple papers that propose multiple k of IU per day.

> There are doctors that are prescribing 5000IU+ daily

What doctors prescribe based on the actual conditions particular patients exhibit (and, at doses that high, often with serum level monitoring) is only distantly related, even in theory, to population-wide recommendations like the RDA.

> I've read lately about multiple papers that propose multiple k of IU per day.

Yeah, so have I, and I personally think (though I’m not an expert in this field) it's likely that the RDA is way too low. But there's a difference between the belief that RDA should be higher and the claim that the RDA has, in fact, been raised. It has not, it's still 600 IU/day.

Doctors may be making those recommendations based on blood tests indicating specific patient deficiencies. As you note, though, research does at least suggest daily vitamin D supplementation in the thousands of IUs per day range may be considered safe.

I'm not a doctor, but I believe if you've been directed by one to supplement vitamin D, blood tests probably should have preceded that recommendation.

I've had one doctor prescribe me 10K a week. Another one recommended no more than 400/day.

Doctors do not agree. Some have jumped on the bandwagon, and others believe it is just a bandwagon.

I was told to take 20,000IU/day, just to be sure. It might be just correlation, but it helped with the issue I had.

Why are most sold supplements in the 3000-5000UI range?

I don't think they are, though there certainly are supplements in that range and higher.

But supplements don't mostly sell based on either science or government recommendations, but fads which are often unrelated to either.

Vitamin D is fat-soluble and can be stored in body fat. Supplements in the higher range are meant to be taken once a week or once a month. Supplements in the 400-1000IU range are meant to be taken daily.

Vitamin D is fat soluble and isn't cleared by the body as quickly as other vitamins such as B. Therefore it can be taken in higher doses, but less frequently. This is often done for convenience sake. A 3000-5000IU pill every week is easier to remember than a 500-600IU pill every day.

I'm on mobile at the moment, but I think there is more than just one paper suggesting that Vitamin D RDI is too low, even if they don't explicitly call for raising the official level?

I can dig for links when I'm back at a Desktop.

I was referring to the one paper cited in the thread, which was being misrepresented as an actual rather than recommended increases to the official RDA. Yes, there have certainly been more than one paper suggesting that higher Vitamin D intake than the current RDA is desirable, but they have not resulted in the RDA being raised as suggested upthread.

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