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As discussed in the Vitamin K Supplements Review, higher intakes of certain forms of vitamin K2 from food are associated with a reduced risk of coronary artery calcification and mortality from coronary heart disease. These benefits have, so far, not been proven with vitamin K2 supplements, although one study showed some improvements in arterial stiffness. More information about this is found in the "What It Does" section of the Vitamin K Supplements Review, which includes's tests and reviews of products including those made with the MK-4 and MK-7 forms of vitamin K2.

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March 3, 2016

I am on warfarin and calcium channel blockers plus digitalis since 2008 because of irregular heart beat, as warfarin is associated with calcification of arteries i have been taking 90mcg of k2 made from natto for at least 2 years it has had very little effect on my bloods ability to clot in fact my i.n.r. readings are more consistant. I have not had any side effects in fact my varicouse veins have not got any worse in 2 years. Richard.

March 2, 2016

The following is not an absolute fact so take it for what's it's worth at face value.
Vitamin K2 Life Extension low dose 50 mcg. I also eat at least 6 eggs/wk and eat grass fed beef and real traditional kefir made daily from raw milk and 2% LTST milk. Why? Grass fed beef and free range eggs have much K4 which converts to K2 in the gut with proper gut microflora, which I have a great deal from the kefir, beef fat, milk, and other fermented foods I eat.
For about 1 1/2 yrs I have been taking LE K2. Recently, as of 11/15 my wife started taking it also. She is 59 yrs old and has been on hypertensive medication since 32 yrs old. It is a calcium channel blocker. Eight days after taking K2 LE daily she began to experience dizziness, heart palpitations, when she bent over and stood up. She is normal weight, low cholesterol, triglycerides...non diabetic. She went off the K2 immed. One month later she went back on. Same thing but worse. Feb. 2016 she tried again and same thing but sent her to the hospital. Every test was done including for blockages all negative. She is fine since eliminating it.
My deduction: K2 is powerful and puts calcium where it belongs and caused her reaction, agonist to the calcium channel blockers. K2 is genuine and works for transport of calcium. I have not had any reactions in 1 1/2 yrs. Oh that K2, it works IMO. Her OBGYN/GP also agrees with me. The cardiologist who thought there was a blockage is baffled.
March 2, 2016

Hi Gary - Thank you for posting your wife's experience. You are correct that vitamin K does effect calcium transport, but we are not aware of any published reports or evidence of vitamin K2 interacting with calcium channel blockers. We'll keep an eye on this.

March 3, 2016

Save a couple of message boards on the net you are correct on the K2/calcium channel blockers/published research. That is the reason why I wanted to present her situation. I also emailed a more detailed essay to Dr. Kate Rheaume-Bleue, BSc., ND. She has written a very good book on:
"Vitamin K2 and the Calcium Paradox." It is of my opinion that excessive K2 can interfere with calcium channel blockers. I think we will find in the future that researchers will find that K2 interacts with these drugs, again, JMO.

June 3, 2019

Fascinating tidbit here. I'd not heard of any vitamins serving in the calcium regulating role to the extent vascular tone might be affected.

August 7, 2020

Hi Gary,
You mentioned a blockage and your doctor is baffled. Could you please elaborate? Thank you!

March 2, 2016

Considering that K2 comes in multiple forms, it would be worth noting which forms were used in the studies which failed to prove benefit from supplementation, or whether they even distinguished.
March 3, 2016

Hi Eric - There do not appear to be many studies available; however, for the studies discussed in the review, ( we have included information on which form of K2 was used.

June 5, 2016


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