Oral Anticoagulants and Vitamin K2
The most common treatment for poor blood flow is to prescribe a vitamin K antagonist, like coumarin or warfarin. These prescribed drugs interfere with vitamin K activity in the liver, by inhibiting enzymes, resulting in the blood’s inability to form an undesired blood clot.
Dietary vitamin K counteracts the activity of these coumarins, which is why patients on oral anticoagulant therapy need to be kept in a delicate balance: Their natural vitamin K intake should be counteracted partly by a carefully calculated dose of coumarin.
The challenge is that the therapeutic window is very narrow. If the dose of coumarin is too high, it may cause bleeding events; but if it is too low, there is risk of thrombosis. This problem is encountered at all levels of vitamin K intake, but in general it is seen that the lower dietary vitamin K intake, the wider the day-to day fluctuations are, and the more difficult it is to maintain the patient in the target window.
Therefore, patients under warfarin or coumarin treatment should not take MK-7 supplements without consulting their medical doctor first.
The narrow therapeutic window may also cause serious adverse reactions, mostly severe bleeding events. (Hemorrhage associated with warfarin is directly related to the level of INR; the risk of hemorrhage is increased if the INR is greater than five.)
Further coumarins will also inhibit the activation of other vitamin K-dependent proteins like Protein S and Z and GAS 6 protein, Osteocalcin and Matrix Gla. The inactivity of the latter two can be detrimental to both bone and cardiovascular health.
Recent studies have found association between long-term anticoagulant treatment and reduced bone quality due to reduction of active Osteocalcin35, as well as two-fold more arterial calcification compared to patients not receiving K vitamin antagonists.36, 37
But the standard of care is changing with the development of a new class of oral anticoagulant that are not vitamin K antagonists and relatively devoid of major safety considerations, expanding treatment options and allowing patients to continue supporting their bone and cardiovascular health with vitamin K2 supplementation. While this is promising, again, consulting with one’s medical doctor is recommended.