I've been taking 6000-8000 IU of vitamin D daily along with K2, with no issues. I recommend using drops instead of pills as they allow for more flexible dosing. They aren't more expensive either (in my experience, they're actually cheaper).

My local grocery store offered free blood testing for Vitamin D a few years ago, and I was low.

I take a 2000IU tablet a few times a week now.

Meanwhile, my daily 5000IU Vitamin D pills were recalled by some authority in Finland for “excessive dose”, and since it appears that a recall anywhere in the EU will apply to the whole EU, I was given a refund and presumably won’t be able to buy it again.

I’ve always been wary of overconsuming fat-soluble vitamins (ADEK). Seeing strong medical consensus that 6000IU/day of Vitamin D is safe and even desirable gives me confidence to supplement more liberally.

Interesting. I live at the 45th parallel, and try to get out into the sun everyday during the warmer months, with 5000IU orally per day during the gloomy part of the year. Now I'm wondering if I should get my levels checked.

In the US, you can get 50000 IU on Amazon, good enough for weekly supplementation if you're low (same as prescription strength).

TLDR Unfortunately, medicine took a very long time to realize that vitamin D is not simply a vitamin that prevents rickets.

We know today that vitamin D is a powerful nuclear receptor-activating hormone of critical importance, especially to the immune system.

With the available data mentioned above, the proposed doses would probably suffice to maintain vitamin D levels around or over 75-100 nmol/L, with practically zero risk of toxicity.