Vitamin K2, aspirin, fish oil and blood thinning

An interesting question came up from one of our Track Your Plaque Members on the Forum.

"I am now taking 9 mg of vitamin K1 and 1000 mcg of K2.

Does taking this supplement with this much K1 have a counteracting effect on the thinning/anticlotting properties of aspirin and fish oil that I also take?"

Great question (along with lots of other greater discussions we have on the Forum.)

The answer: Vitamin K should have no effect on the platelet-blocking effects of aspirin or fish oil. The majority of blood clot inhibiting effects of aspirin and fish oil arise from their ability to keep blood platelets from "clumping" (just like the TV commercials for Plavix).

Vitamin K, on the other hand, participates in the liver production of blood clotting factors (like II, VII, IX, and X, among others for you curious ones).

Thus, vitamin K-dependent clotting factors and platelet-blocking are two separate pathways to forming blood clots. Some of us refer to the difference as "red clots" from the vitamin K pathway and "white clots" from the platelet pathway, since they really do have this different physical appearance.

The vitamin K2 conversation, like that about vitamin D, is fascinating for its potential to provide the missing link between the tightly-tied fortunes of bone health and atherosclerosis. Why is someone with a high CT heart scan score far more likely to have osteoporosis? Vitamin D and K2 deficiency may provide the missing link for many people.

Comments (12) -

  • Anonymous

    5/28/2007 2:23:00 PM |

    Dear Dr. Davis;   thank you so much for your blog...praying you reach many people.

  • Anne

    5/28/2007 8:06:00 PM |

    Is there a test for K2 deficiency? I have both osteoporosis and CAD. I have asked my doctors about vitamin K, but neither could tell me anything about it.

    What is the difference between K1 and K2?

    Great blog. Thank you.

  • Dr. Davis

    5/29/2007 1:25:00 AM |

    I have not yet been able to find a laboratory that makes K2 measurements available. However, it is a safe assumption that, unless you ingest fermented traditional cheeses (not Velveeta, etc.), pate or liver, or natto (blechh!), then there's an excellent chance you are deficient. To my knowledge, there is also no definition of deficiency, even if we were able to obtain a blood value. This will unfold over the next two years as data trickles out and experience accumulates.

  • Cindy

    6/3/2007 1:40:00 AM |

    What is a good dose for Vitamin K? Sine I'm not much of a cheese eater, or liver for that matter, I figure it can't hurt to take a supplement....but have no idea how much to take!

  • Dr. Davis

    6/3/2007 2:51:00 AM |

    The problem is that there is no dose.
    Based on available data, we have been advocating a dose of 1000 mcg (1 mg) per day, though the evidence is, admittedly, slim to support this specific dose. Changes are possible--probable--in future, as the experience develops.

  • BelieveIt

    2/12/2008 2:30:00 AM |

    Vitamin K test available at

    Differences between K1 & K2 also discussed at

    aCCORDING TO THE ABOVE:  Tufts University tests the vitamin content of foods for the U.S. Department of Agriculture which maintains a database. Not too long ago, new technology allowed a more precise determination of the vitamin K content of food. Using the new technology, Tufts researcher Dr. Sarah Booth discovered that the vitamin K content of most foods is lower than researchers previously thought.

    Green leafy vegetables supply 40-50% of vitamin K for most Americans. Vegetable oils are the next highest source. Hydrogenated oils (margarine, for example) create an unnatural form of K that may actually stop the vitamin from working.

    There are three different types of vitamin K: K1 which is from plants, K2 which is made by bacteria and K3 which is synthetic. Vitamin K3 is generally regarded as toxic because it generates free radicals. This version shows promise in the treatment of cancer. K2 specifically keeps calcium and phosphorus out of the aorta, and reverses the effects of heart-unfriendly diets. The body converts K1 to K2.

    Dosage and precautions

    Vitamin K is not stored in the body, and is therefore nontoxic in high amounts. Forty-five milligrams a day were used in osteoporosis studies without any ill effect. Vitamin K has been approved in Japan for the treatment of osteoporosis since 1995. Several thousand times more than what people are currently getting in their diet has been taken without any toxicity. Dosage depends on an individual's diet, age, whether they are taking drugs, and what stressors are present. Generally, 10 mg/day is recommended.

    If you want to get your vitamin K level tested, request the osteocalcin test. It is much more reliable than coagulation tests. The osteocalcin test measures how much carboxylated osteocalcin you have. Since carboxylation is dependent on vitamin K, this test will give you a good idea of your vitamin K status, and whether or not you're headed for osteoporosis and possibly heart disease.

  • Anonymous

    1/16/2009 11:29:00 PM |

    An article at the Weston Price Foundation suggests that high amounts of vitamin K1 supplementation might not be correct. The author states:

    These results show that our absorption of the vitamin [k1] declines as the amount we consume increases and strengthens the interpretation that we might only be able to absorb about 200 micrograms per day. [of K1 from vegtables] …

    Preliminary evidence indicates that doses of 1000 micrograms per day of supplemental K1 may contribute to periodontal disease,31 suggesting that our bodies' resistance to absorbing this much K1 from vegetables may serve an important purpose.

  • Anonymous

    4/16/2009 2:49:00 PM |

    My mother-in-law is taking nattokinase for blood clot protection and disolving a clot in her caratoid retinal artery. Would taking K2 with natto kinase interfere with the clot disolving action of nattokinase?

  • Anonymous

    4/16/2009 2:51:00 PM |

    My motherinlaw is taking nattokinase and k2 together. She had a clot in her retinal artery causing some vision loss. Would taking k2 together with nattokinase dimish of help the nattokinase effect of disolving this blood clot?

  • Sal

    7/29/2009 4:52:05 AM |

    Dear Mr Davis

    Iam  lately diagnosed with arterial calcification in my lower limbs. I have no diabetes, no cholestrol issues nor any kidney or blood pressure issues, yeah I do have some anxiety.

    Please tell me whether taking vitamin k2 supplements would help. Also is there a test to find out if I am defecient in vitamink. What is the best supplement I can take.

    Kindest Regards
    Salim Khatri

  • Anonymous

    11/19/2009 2:30:39 AM |

    Actually, aspirin is a vitamin K antagonist. It is sort of silly to take an antagonist AND vitamin K.
    Further, if aspirin effectively blocks the K from working, the aspirin is maybe preventing platelets from clumping, but preventing inappropriate calcium deposition and therefore leading (over a long time) to arteriosclerosis and therefore CVD.
    Vitamin K2 is made by bacteria and found in fermented foods and animal organ meats. These are two food groups that have strong cultural ties, but they are lost as various cultures have blended into the American culture of some pretty heinous foods.
    So eat sausage, sauerkraut, pickles, natto, kimchee, organ meats and avoid pasteurized of the above and this may kill the bacteria that are making the K2.

  • buy jeans

    11/3/2010 10:32:34 PM |

    Vitamin K, on the other hand, participates in the liver production of blood clotting factors (like II, VII, IX, and X, among others for you curious ones).