I've been meaning to write this post for a while but never got around to it - but Christo has nudged me to get on and do it!
In summary, I've had great success stabilising my INR using Vitamin K2. And I don't bother about what I eat or drink either. All I do is take 1 tablet of 90mcg of Jarrow MK-7 Vitamin K2 per day at the same time as my warfarin.
In more detail, I had read research showing that vitamin K helped stabilise INR. For instance:
"Low-Dose Vitamin K to Augment Anticoagulation Control "
This showed that supplementation with low does Vit K increased the number of INR's in range by 76%.
In another study from the University of Oxford:
"Vitamin K for improved anticoagulation control in patients receiving warfarin"
It was found that in one study, Time in Therapeutic Range (TTR) (i.e. time with INR in 2-3 range) increased from 59% before the trial to 89% afterwards.
This is also a good summary:
"Low Dose Vitamin K Supplementation and Anticoagulation Control"
As it states: "Although it may seem counter-intuitive, increasing evidence has shown that the common anti-green vegetable lecture imparted to all patients starting warfarin may actually be doing more harm than good. Such advice may be setting up patients for a widely variable and difficult to manage INR. Low-dose vitamin K supplementation may actually improve the stability of anticoagulation therapy."
To give you an example of why Vit K supplements work:
Suppose your average Vit K intake in 10mcg p.d. and varies by 5 mcg (i.e. between 5 and 15mcg p.d.). This will lead to a variation of up to 300% in Vit K intake. However if you take a supplement of 90mcg of Vit K, the total intake varies between 95mcg and 105 mcg - a variation of only 10%.
I use vitamin K2 rather than the more common vitamin K (which is actually vitamin K1). This is because Vit K2 is hown to counter some of the side effects of warfarin such as possible artherosclerosis. See this article:
- scroll down to the "Response" on page 2.
The K2 version also has a longer half life in the body and is effective at helping prevent osteoporosis and osteoarthritis and reduces the risk of prostate cancer.
Since starting Vit K2, my INR dropped slightly initially, and I had to increase my warfarin from about 7.5mg to 8mg. I have now being taking K2 for about 5 years and my INR is in range about 99% of the time, usually in the 2.3-2.8 range. I eat a very varied diet paying no attention to the amount of Vit K included. So it works very well for me. I've mentioned this to Prof Schilling who was very interested and supportive. However you might get a different reaction from less educated doctors whose standard knee jerk reaction is negative! I would caution anyone wanting to try K2 out to do their research however and also get a Coaguchek monitor.
The result is that with a TTR of 99%, warfarin is more effective than any of the new OACs by some margin.