PN - Vitamin D = Good/Bad? Yes

The “K” in vitamin K comes from the German koagulation. Coagulation refers to the process of blood clot formation. This should hint to you that vitamin K plays a crucial role in the body’s blood clotting pathway.

Put simply, vitamin K allows the body to use calcium to perform its clotting function.

If vitamin K is low, the body can’t use calcium in this way, and therefore, cannot clot.

Besides its role in clotting, Vitamin K also helps to form and maintain our bones and teeth.

It does so by activating a specific protein called osteocalcin that helps the body use calcium and deposit it where it belongs.

In other words, there is a very potent calcium-vitamin K connection in that vitamin K helps the body use calcium properly. And if we’re deficient in vitamin K, calcium levels can build up and deposit themselves in our soft tissues.

People who are low in vitamin K are more likely to suffer from atherosclerosis, or calcification of the arteries.

And those with a high vitamin K intake (especially vitamin K2) seem to have less calcification of their arteries.

In fact, research in rats has shown that supplementing with vitamin K2 (but not K1) not only inhibits arterial calcification, it can also remove 30-50% of the calcium that has already been deposited.

Unfortunately, this magic effect has not been shown in humans as yet.

Hopefully by now, you can see the delicate dance that’s going on. Vitamin D increases calcium levels in the body. Vitamin K helps the body use calcium.

So if one were to supplement with high-dose vitamin D in the presence of vitamin K deficiency, the long-term results could be disastrous.

http://www.precisionnutrition.com/stop-vitamin-d

PN's conclusion: in the presence of other deficiencies, we should be careful of supplementation with vitamin D.

I think PN is right, because as the article explains, each of these micronutrients works in conjunction with each other.  D and K balance each other, in conjunction with magnesium and calcium and vitamin A.  Eat meat, vegetables, nuts and seeds, little fruit or starch, no sugar/wheat.