Vit D, Vit K and warfarin

I am writing on behalf of my cousin, who is hypo and on NDT. She is taking Vit D3 and Vit K2 but is concerned as she is now also on blood thinners from her GP, following a kind of mini stroke. Is there anyone who can please advise about different types of Vit K and whether there is one that is compatable with warfarin? If not, should she stop the Vit D or just reduce it? She's taking 5000iu Vit D3/day. Many thanks.

17 Replies

  • The issue isn't actually the vitamin D3 but the K2. What is her vitamin D level plus units or range?

    Scroll down to 10. Who Should NOT Take Vitamin K? -

    This article doesn't separate K1 and K2 -

    Low levels of vitamin D linked to severe strokes



  • Thank you very much for this. I have forwarded the links to her. It's Solar Vit K2 (MK-7) 100 mcg that she takes with 5,000iu Vit D3. In fact, I have found out it's not Warfarin, but is a blood thinner called Clopidogrel, 75mg/day. I vaguely remember reading something about K2 and K1, but can't remember where it was and what the relevance of the two were in relation to blood thinning agents.

  • I don't know about 'compatible with warfarin' but K2 has nothing to do with blood clotting. That's K1.

    Vitamin K2 directs calcium to the bones and teeth, so that it doesn't go into the tissues and arteries. Personally, I think vit K2 is important for people with heart problems for that reason. But when they are given vit K blockers, to prevent blood clots, that blocks the K2 as well as the K1, which could mean that the person ends up with calcium clogged arteries and has a heart attack, anyway. I've never been able to figure that out...

  • One of the issues with the K vitamins is they haven't worked out how much people need.

    The one study I've read has stated you need 100mcg of K2 per 5,000-10,000IU of vitamin D, while another was on prostate cancer where they gave the subjects 65mcg.

  • Thanks Bluebug. I imagine that like other vitamins, there is a "maintenance" dose and a "therapeutic" dose.

  • Thank you very much for that information. Wow - pretty important not to get your K1 and K2 muddled up!

  • The paper below refers to Warfarin actually CAUSING vitamin K deficiency:

    Asia Pac J Clin Nutr. 2013;22(3):492-6.

    Clinical decision-making for vitamin K-1 and K-2 deficiency and coronary artery calcification with warfarin therapy: are diet, factor Xa inhibitors or both the answer?

    Wahlqvist ML1, Tanaka K, Tzeng BH.

    Author information

    1 Institute of Population Health Sciences, National Health Research Institutes, Miaoli County, Taiwan, Republic of China.


    Coronary artery calcification is a recognised risk factor for ischaemic heart disease and mortality. Evidence is now strong that Mönckeberg's arteriosclerosis, a form of vascular calcification, can be attributable to vitamin K deficiency, but that vitamin K-2, especially the MK-4 form from foods like cheese can be protective. Warfarin blocks the recycling of hepatic and peripheral vitamin K leading to secondary vitamin K deficiency with adverse effects on vasculature, bone, kidneys, brain and other tissues and systems (inflammatory, immune function and neoplasia at least). There is individual susceptibility to vitamin K deficiency and warfarin sensitivity, partly explicable in terms of genetic polymorphisms, epigenetics, diet and pharmacotherapy. The emergence of extensive coronary calcification in a man with atrial fibrillation treated for a decade with warfarin is described by way of illustration and to raise the present clinical management conundrums. Finally, a putative set of recommendations is provided.

    PMID: 24066371 [PubMed - indexed for MEDLINE]

    Free full text

    The free full text is available here:

  • Does anything on that link make any distinction between K1 and K2?

    I am no expert but the fact is that almost all references to vitamin K do NOT identify whether they are referring to K1 or K2 - and the two are very different.

  • Are you talking about K1 or K2? Do you know there is a difference. K1 thickens the blood. K2 stops the arteries getting clogged up with calcium and causing a heart attack. They are completely different things.

  • My GP would have been mortified that I was taking 4,000IU - 6,000IU of vitamin D after the local guidelines advised a maximum of 2,000IU after I had been found severely vitamin D deficient and had my loading doses. However when I had a test that showed I was still vitamin D insufficient she wasn't bothered about me following the guidelines she just wanted me to get my level up asap.

    Anyway one of the links on vitamin K, which unfortunately doesn't distinguish between vitamin K1 and vitamin K2, states if you are already consuming vitamin K then have a stroke don't modify your consumption.

  • Now outdated research - Taking K has been show to help stablise warfarin dose. But it takes at least 17 years for research to make it to mainstream and probably double that for the NHS.

  • Oh my I have been taking clopidigrel for two years since my stroke and I'm taking vit k2! Should I stop taking them?

  • My opinion is no, you should not stop taking K2. But do your own research so that you understand the difference between K1 and K2.

  • Ok thanks grey goose I am not currently taking vit D as I'm out in the sun alot now. Will try to get a blood test to see where my levels are at now...

  • OK, but vit K2 is still a very important vitamin.

  • What sun?

  • K1 does blood clotting. Low dose K2 (45mg) should be OK according to LEF.

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