I was told recently that I should not be taking doses of daily vitamin D3 higher than 2000IU (I take 10000IU/day) without supplementing vitamin
K2 MK-7 as well, because without a correct ration of D3 to
K2, inappropriate calcification (of arteries) can occur. In researching, I've learned that vitamin K2 MK-7 supplements come from natto, a Japanese fermented soy product.