I took 10k iu via a multivitamin for a few months, and ended up with Vitamin D levels 5x higher than the maximum on the labcorp reference range. "Vitamin D toxicity"
It took many months to get the levels back to normal. Vitamin D is one of those things that once you overdose, it takes many months for the levels to slowly come down after you stop supplementing.
Be careful with Vitamin D!
The downside to having high levels is plaque/calcium deposits in arteries, if I'm not mistaken. Which can be mitigated by taking K2.
Are you aware of the history of setting acceptable levels of Vitamin D? Basically, 100 years ago, people experimented with cures for TB by giving patients one to two orders of magnitude higher dosage than the "vitamin D toxicity" levels reported today. Like insanely high numbers. Strangely enough, most people did recover from the TB, but they kept getting the treatments anyway, and that in a few instances led to bone issues. So for some reason that doesn't seem to be documented, they set the "safe level" of vitamin D to be something like two orders of magnitude lower than the level that actually caused issues. And that level has never been changed.
All of the studies I've seen around Vitamin D supplementation has shown that the "safe level" reported today is way, way lower than it should be. People appear to be just fine taking 10k IUs for months on end, even 7 years in one study. I think what we're learning is that the "safe level" is a very wide spectrum; some people could possibly be harmed from a low level, whereas some people are perfectly fine at a very high level.
And, fixed dosage never makes sense with Vitamin D. If you're supplementing, you need to make sure you regulate it based on sun exposure, since it's literally the Sun vitamin.
It's easy to double up if you decide to eat lunch outside because the weather is nice this month. I take 10k only if I'm indoors all day, and reduce or take none if I'm out.
> An excess of vitamin D causes abnormally high blood concentrations of calcium, which can cause overcalcification of soft tissues, including arteries and kidneys. Symptoms appear several months after excessive doses of vitamin D are administered. A mutation of the CYP24A1 gene can lead to a reduction in the degradation of vitamin D and thus to vitamin toxicity without high oral intake (see Vitamin D § Excess).
> Treatment
> In almost every case, ceasing vitamin D intake, combined with a low-calcium diet and corticosteroid drugs, will allow for a full recovery within a month. Bisphosphonate drugs (which inhibit bone resorption) can also be administered.[2]
Regardless, blood levels need to be checked for this sort of thing and doses are not one-size-fits-all. I also once was taking 10k daily, for several months, and ended up just barely in excess territory with no noticeable symptoms. (I settled on taking 4k daily in the long term.)
> In almost every case, ceasing vitamin D intake, combined with a low-calcium diet and corticosteroid drugs, will allow for a full recovery within a month.
Surprised to see just 4 weeks for a recovery. I got retested after 8 weeks (only minor improvement) and wasn't until 16 weeks until the test finally came back in range.
100% no dose is one-size-fits-all. I overdosed from taking a specialty multivitamin (it has a discord channel and everything). So was chatting with people taking the same vitamin, same dosages, also getting tested, but others had no issues at the same doses.
I guess I just absorb vitamin D with great efficiency, who knows.
And yeah, it does not absorb well unless you eat some fat.