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Comment by hammock | Hacker News Reader

The widely used daily recommended amounts of Vitamin D (600 IU in the US and Canada) are wrong, by a factor of 10, and based on a math typo that no one caught until 2017: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5541280/. I guess many still don't realize this fact.

"We call public health authorities to consider designating as the RDA ... around 8000 IU for adults"

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This should be its own HN submission. I want a discussion on this.

Edit: nevermind, it was posted 2 times already [1, 2].

[1] https://news.ycombinator.com/item?id=24768721

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

That's if you don't count the other fifty health threads it came up in...

Isn’t the issue made worse by the fact that Vitamin D absorption is way lower if not in conjunction with Vitamin K? Or is this a myth?

Vitamin K is needed so that calcium doesn't build up in the vessels but goes to the bones where it's supposed to be. But, taking D and K at the exact same time reduces the absorption of D.

K2, to be precise. K is involved in blood clotting; K2 isn’t.

So those combination vitamin D, and K products are scams?

Not at all. Suboptimal, but far better than taking nothing at all.

There are loads of nutrients that technically compete for absorption, but generally it isn’t a concern unless you are taking a huge dose of one. Even then, it’s not like little dog is completely blocked. I’d have to look at the studies the above comment is referencing to determine how much of a concern it actually would be.

Even if taking both together was 30% less effective than taking them apart, in the context that getting people to take a single pill daily with regard to timing is hard enough, it’s still a overall win. That said, I would agree such a situation should be reflected on the label.

“Less effective” is odd here because other commenters are saying that K2 ensures D gets deposited in the right places rather than build up in the arteries (as plaques presumably). So if it is, say 30% less effective, then taking them apart wouldn’t that mean that rather than getting (example) 1,000 IU in the wrong place, you’d get 700 IU deposited in the right place, so it would be more effective rather than less?

Every packaging label I’ve ever seen clearly claims how many IUs there are.

Let’s say it is 30%, there’s no way potential buyers, when they see ‘1000 IUs Vitamin D’ for example, will realize it actually means ‘700 IUs’.

So I don’t see how your comment makes sense.

The whole idea is that some research suggests that vitamin D may be harmful without vitamin K to offset its effects ("so that calcium doesn't build up in the vessels but goes to the bones where it's supposed to be"). That's all there is to it.

No need to discuss absorption. Furthermore, the idea "taking D and K at the exact same time reduces the absorption of D" is unsubstantiated in medical research

700 instead of 1000 would be “sub optimal” but better than 0. At least that’s what I think the above poster was trying to say.

As mentioned, K is more to make sure the calcium absorbed as a result of vitamin D can be properly put away instead of hanging around in the arteries.

Magnesium is very important cofactor for metabolism of Vitamin D (and many other things, it’s a cofactor involved with hundreds of enzymes and such), which people are also generally low on.

I think there may be another big cofactor or two, but they escape my offhand recollection.

absolutely on the Magnesium. Due to our diets being primary processed wheat, sugar, oil, and animals, (and partially due to soil mineral depletion) our diet is persistently low on Magnesium by quite a large margin. the impact of this on the population is not consistent. this really doesn't get enough attention in the media or many other places.

So take Magnesium and D together?

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4210929/

Is the article that talks about the miscalculation

Interesting that they found that to meet the target threshold, you'd need to take well over the "tolerable upper intake" or 4000 IU.

That was ten years ago, so was the recommendation updated? If not, I must assume the error might be in the newer calculation.

I'm reminded of "a lot of engineering is ensuring that you made an even number of sign errors."

(That is, if the original calculations are wrong, but the result usually works out, it might not be caught.)

Can you corroborate their opinion with other sources? It’s not very evidence based.

https://vitamindforall.org/letter.html is a letter that goes into why >= 4000 IU daily is recommended based on blood serum levels with more literature review.

Incredible.

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