Hello jarno,
Reading posts from forum member "newmitral" I also get the impression that the K2 affects the INR.
Reading your posts, and pellicle's, I feel it might be helpful to interject a few bits of info/opinion here.
I did a lot of research before starting to take the K2 supplement to help stabilize my INR. Many reports I found were scholarly studies from peer-reviewed journals, not just "some guy on the internet". I don't have those references handy, but I'll try to find and post them if I have time over the weekend.
I found one piece of info on the web stating that the K2 would be much "stronger" than K1 and great care should be taken as a small dose of the K2 would be able to wipe out the effects of warfarin. Keeping my fingers crossed that is not true.
The information I found (from memory, so I might be off a bit), was that K2 lasted much longer in the system than K1. It is not so much that it is "stronger" but that if you are taking it every day, the concentration will build up to a higher value in your body because your system doesn't clear it as fast. It is for this reason that I started out with the very low daily dose (45mcg) and have only recently built up to a daily dose of 90mcg.
so its my own 'deduction' that K2 should not effect INR directly because its K1 that is involved in prothrombin reactions, but may it have an effect on it via other reactions.
I just don't know ...
I previously posted my INR variations for a 6 month period in this post:
http://www.valvereplacement.org/forums/showthread.php?41441-frequency-of-testing&p=535642#post535642
You can see a fairly dramatic indication that K2
DOES impact INR in the tests on
2012-11-10 - INR = 4.4
2012-11-14 - INR = 2.8
2012-11-17 - INR = 4.3
When I measured (and confirmed) the 4.4 reading on Nov.10 (Saturday) I took some extra K2 pills to help bring the INR down quickly. I did also reduce my daily warfarin dose from 12.5mg to 6mg that Saturday evening, then back to normal 12.5mg Sunday onwards. The results on Nov. 14th, (the following Wednesday) of 2.8 are a combination of the reduced warfarin the previous Saturday, and the extra K2. By the next measurement on Nov 17th (Saturday) the INR was back up to 4.3, and my suspicion is that the extra K2 had by then been cleared from my body, and the INR went back up as a result. Admittedly, these results are anecdotal, not an analysis of the chemical mechanisms involved, but my personal experience leads me to conclude that K2 has an interaction similar to K1 as far as the INR and warfarin are concerned.
On a related note, I have subsequently tested whether cranberry juice might be the cause of the spikes in INR, a suspicion mentioned in that earlier post. Upon further testing, I can not confirm any correlation between cranberry juice and my own INR volatility, so that isn't the cause.
Further info:
On May 25th, 2013, I increased my daily K2 dose from 60mcg to 90 mcg. Statistically, for the weekly INR results between 2013-06-01 and 2013-09-21, my mean INR = 3.04 (my range is 2.5 to 3.5) and the standard deviation has dropped to 0.36 (it was 0.57 when I was taking 60mcg/day of K2 - the results posted in the other thread).
I also have achieved a new "personal best" of not going out of range - either above or below - for 7 consecutive weeks.
So, as far as my own personal experiment goes, I'm pleased with the apparent INR stabilization effects of the K2 supplement. If you are not experiencing the very large variations I had been seeing, swinging from above range to below range in a week with stable lifestyle, stable diet and no other medications, then I'm not sure the benefits will be as obvious. But, as long as you are careful, and test frequently, you should be OK. I did also check with my doctor before embarking on this experiment, and showed him the medical journal papers that supported the experiment, and he was in agreement. You may want to consult with your own doctor as well just to let him know.
While I did expect the K2 to require me to increase my warfarin dose, I only really went from 12.0 mg/day to 12.5 mg/day so the overall increase in warfarin dose was not that significant for me.
Again, these are just my own personal stats as a result of my experiment with the K2 supplement to stabilize my INR. Your own results may vary, and I would also be interested to hear how it goes for you.
Also, I think this thread:
http://www.valvereplacement.org/forums/showthread.php?37453-Vitamin-K2-and-Warfarin
might be the one where I first saw speculation that K2 might be beneficial for INR stabilization as well as other health benefits.