Do you have a source for the 10000 IU per day guideline? If that's D3, that's 25 times to "recommended" amount, well above what is considered safe for long-term use. Now, I realize that our understanding of these things are in a state of (often violent) flux, but I would like to know who's recommended such a high amount. The problem with Vitamin D is that it is fat-soluble, not water-soluble, so your body doesn't expel the excess very quickly and it builds up. Too much can be harmful, particularly to your bones and kidneys[1].
> well above what is considered safe for long-term use.
The Mayo clinic article says:
> Taking 60,000 international units (IU) a day of vitamin D for several months has been shown to cause toxicity.
So 10,000, while it's well above the "recommended" dosage, is nowhere near the toxic level. Although when I was looking around the toxic level was 20,000, still, I've seen no guidance regarding Vitamin D that suggests 10,000 IUs/day can be toxic. (Especially if your BMI is over 25, and you're not getting much sunlight.)
Mayo clinic article concerns excessive supplementation, isolated on vitamin D, specifically.
A hypothesis exists that increasing vitamin K consumption in proportion to the vitamin D, and restricting calcium intake, would eliminate the main symptoms of excessive vitamin D supplementation. Nonhuman animal experimentation confirms, but it has not been tested in humans (likely due to the obvious ethical concerns).
Vitamin D, vitamin K, and calcium are all related.
I have seen guidance specifically for vitamin D2 (ergocalciferol), indicating that adverse symptoms may be observed at lower levels of supplementation than for vitamin D3 (cholecalciferol), but it was quite some time ago, and I don't know if the claim was confirmed or refuted scientifically.
I know you have faith that taking large doses of vitamin d isn't dangerous, but there is very little evidence supporting its value. We all have to make serious decisions every day without scientific support, so I don't begrudge you the right to do what you believe is best for you. But don't you think it's a little irresponsible to try to convince people that this belief of yours is actually effective? AFICT, there's as good a change that your advice will take ten years off of a life as it has of improving life. And you want to push this on others?
That's a good read. He says you can go high (10000 IU/day) for 6-10 months, under doctor's supervision, then cut back down 2000-4000/day. This also makes sense from the perspective that it's fat-soluble, so you should be able to "fill up the tank" as he puts it.
Thankfully it was posted to HN so I could find it. Google search has a truly become useless for this stuff. It's early in the morning, but I think I'm reading the abstract right. [1]
To add some anecdotal info, those numbers are much more closer to my own personal experience. I've been experimenting with various dosages, with regular blood tests by a doctor, for a few years now. Currently I've setteled at 4000 IU/day to stay at 75 nmol/L, which is the lower end of what is considered normal.
[1] https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-h...