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Frequently Asked Questions about K2

Will K2 cause my blood to clot?

No. This is because, under normal circumstances, the body’s clotting proteins are already occupied by vitamin K1. As such, no amount of vitamin K2 – or K1, for that matter – from food or supplements appreciably affects blood clotting. The one exception to this rule is for people on warfarin (Coumadin). Warfarin works by creating a vitamin K deficiency in the body so vitamin K1 or K2 from any source will counteract the action of the drug and restore the clotting capacity to (or closer to) the normal, un-medicated clotting.

Can I take vitamin K2 with my blood thinner?

It depends on which blood thinner you are taking. Vitamin K (K1 and K2) interacts with warfarin (Coumadin). It will counteract the action of this drug, which will result in an adjustment (raising) of the dose required to achieve a therapeutic INR. While evidence suggests that small, consistent daily doses of vitamin K1 or K2 will prevent INR fluctuations, this can be achieved through diet (like by eating the exact same amount of broccoli or brie cheese everyday). You ultimately can’t get the benefits of vitamin K2 supplements while taking warfarin, so don’t bother.

Vitamin K (K1 or K2) does not interact with other blood thinners such as clopidogrel (Plavix), dabagitran (Pradaxa), prasugrel (Effient), rivaroxaban (Xarelto), aspirin or fish oil. These drugs thin the blood by mechanisms unrelated to vitamin K.

Since K2 reduces plaque, won’t it increase the risk of a clot or heart attack as pieces of the plaque break off?

This is a FAQ since as we understand K2 helps reduce arterial plaque it is easy to imagine it being chipped away or breaking off in chunks. That is not the way K2 shrinks plaque and K2 supplementation has never been associated with a cardiovascular event. In fact, vitamin K2-dependent proteins make plaque more stable and less prone to rupture. Recent clinical trials for reducing plaque in a group known to be at high risk for calcifications used MK-7 in does of around 360 mcg per day with no significant adverse effects (a few participants experienced stomach upset at this dose).

What is a good dose of vitamin K2?

The most recent clinical trials use 180 mcg per day for bone health and 360 mcg daily for arterial calcifications.

What is a good ratio of vitamin K2, vitamin D and vitamin A?

There isn’t an established ratio of the fat-soluble nutrients. The rule of thumb I go by is equal amounts of A and D with 100 mcg K2 (as MK-7) per 1,000 IU A/D. Doing the math you will notice that beyond 5,000 IU D/A this gets pricey and we don’t know if increasing the dose of D necessitates an ever-increasing dose of K2 or if the demand and benefit caps out at some point. So, since vitamin A has K2-sparing effect, I suspect that it is OK to stick at 500 mcg MK-7 (or 5,000 MK-4) even while increasing the other fat-soluble vitamins.