Food sources of vitamin K2

Vitamin K2 is emerging as an exciting player in the control and possible regression of coronary atherosclerotic plaque. Only about 10% of dietary vitamin K intake is in the K2 form, the other 90% being the more common K1.

The ideal source of K2 is natto, the unpalatable, gooey, slimy mass of fermented soybeans that Japanese eat and has been held responsible for substantial decreases in osteoporosis and bone fractures of aging. Natto has an ammonia-like bouquet, in addition to its phlegmy consistency that makes it virtually inedible to anyone but native Japanese.

I say that the conversation on vitamin K2 is emerging because of a number of uncertainties: What form of vitamin K2 is best (so-called MK-4 vs. MK7 vs. MK-9, all of which vary in structure and duration of action in human blood)? What dose is required for bone benefits vs. other benefits outside of bone health? Why would humans have developed a need for a nutrient that is created through fermentation with only small quantities in meats and other non-fermented foods?

Much of the developing research on vit K2 is coming from the laboratories of Drs. Vermeer, Geleijnse, and Schurgers at the University of Maastricht in the Netherlands, along with several laboratories in Japan, the champions of K2.

MK-7 and MK-8,9,10 come from bacterial fermentation, whether in natto, cheese, or in your intestinal tract; MK-4 is naturally synthesized by animals from vitamin K1. While natto is the richest source of the MK-7 form, egg yolks and fermented cheeses are the richest sources of the MK-4 form.

Chicken contains about 8 mcg MK-4 per 3 1/2 oz serving; beef contains about 1 mcg. Egg yolks contain 31 mcg MK-4 per 3 1/2 oz serving (app. 6 raw yolks). Hard cheeses contain about 5 mcg MK-4 per 3 1/2 oz serving, about 70 mcg of MK-8,9; soft cheeses contain about 30% less. Natto contains about 1000 mcg of MK-7, 84 mcg MK-8, and no MK-4 per 3 1/2 oz serving.

Feta cheese

Thanks to the research efforts of the Dutch and Japanese groups, several phenomena surrounding vitamin K2 are clear, even well-established fact:

--Vitamin K2 supplementation (via frequent natto consumption or pharmaceutical doses of K2) substantially improves bone health. While K2 by itself exerts significant bone density/strength increasing properties in dozens of studies, when combined with other bone health-promoting agents (e.g., vitamin D3, prescription drugs like Fosamax and calcitonin), an exaggerated synergy of bone health-promoting effects develop.

--The MK-4 form of vitamin K2 is short-lived, lasting only 3-4 hours in the body. The MK-7 form, in contrast, the form in natto, lasts several days. MK-7 and MK-8-10 are extremely well absorbed, virtually complete.

--Bone health benefits have been shown for both the MK-7 and MK-4 forms.

--Coumadin (warfarin) blocks all forms of vitamin K.

Interestingly, farm-raised meats and eggs do not differ from factory farm-raised foods in K2 content. (But please do not regard this as an endorsement of factory farm foods.)

Another interesting fact: Since mammals synthesize a small quantity of Vit K2 forms from vitamin K1, then eating lots of green vegetables should provide substrate for some quantity of K2 conversion. However, work by Schurgers et al have shown that K1 absorption is poor, no more than 10%, but increases significantly when vegetables are eaten in the presence of oils. (Thus arguing that oils are meant to be part of the human diet. Does your olive oil or oil-based salad dressing represent fulfillment of some subconscious biologic imperative?)

If we believe the data of the Rotterdam Heart Study, then a threshold of 32.7 micrograms of K2 from cheese yields the reduction in cardiovascular events and aortic calcification.

It's all very, very interesting. My prediction is that abnormal (pathologic) calcium deposition will prove to be a basic process that parallels atherosclerotic plaque growth, and that manipulation of phenomena that impact on calcium depostion also impact on atherosclerotic plaque growth. Vitamins D3 and K2 provide potential potent means of at least partially normalizing these processes.

As the data matures, I am going to enjoy my gouda, Emmenthaler, Gruyere, and feta cheeses, along with a few egg yolks. I'm going to be certain to include healthy oils like olive and canola with my vegetables.

All images courtesy Wikipedia.

Copyright 2007 William Davis, MD

Comments (46) -

  • MAC

    12/28/2007 5:58:00 PM |

    Is not magnesium also a regulator of calcium?

    NIH link on magnesium:
    though they really don't spell out magnesium's role in regulating calcium, just that it "keeps bones strong".

    Dr. Eades blog on magnesium and it's deficiency and role in inflammation:

    BTW Dr. Davis, Dr. Eades recently posted a comment on your TYP book as the best source regarding CT heart scans.

  • Anonymous

    12/28/2007 7:05:00 PM |

    Fascinating! Perhaps K2 is one factor that contributes to the so-called French paradox. It might make sense to eat imported cheeses produced by traditional methods in European countries that have the lowest rates of CHD -- France, Portugal, Italy, Spain, and Switzerland.

    In addition to vitamin K, many other fat-soluble nutrients (lycopenes, carotenoids, etc.) in plant foods simply aren't absorbed unless accompanied by fat, which, ironically, renders those "healthy" fat free salad spritzes downright hazardous to health.

  • Anonymous

    12/28/2007 7:33:00 PM |

    Great blog, enjoyed reading about vitamin K2.  

    With recent findings on the importance of bone strengthening supplements and drugs for heart health, would weight lifting be helpful at bringing about plaque regression?

  • Carl H

    12/28/2007 8:14:00 PM |

    What about Miso?  Another fermented soy product.  Not bad + not natto.

  • Dr. Davis

    12/28/2007 11:06:00 PM |

    Hi, Mac--

    Yes, magnesium is among the three nutrients that I fuss about for bone and arterial health, along with K2 and D3.

    Thanks for the heads up on Dr. Eades blog. I've only recently stumbled across his Blog and found it wonderful, full of unique and refreshingly candid comments.

  • Dr. Davis

    12/28/2007 11:07:00 PM |

    No, not specifically. K2 improves bone health and possibly arterial health. Weight lifting improves bone health. But that's as far as the intersection goes.

  • Dr. Davis

    12/28/2007 11:08:00 PM |

    I love miso and was raised on it. But to my knowledge it is not a significant source of K2.

  • Cindy Moore

    12/29/2007 8:29:00 AM |

    "--Coumadin (warfarin) blocks all forms of vitamin K."

    Do you know if there is any evidence that long term (20 yrs+) warfarin use may increase risk?

  • Anonymous

    12/29/2007 8:58:00 AM |

    My research shows that CoQ10 has a structure very similiar to vitamin K.  Perhaps supplementation with CoQ10 may help provide Vitamin K2.

  • Dr. Davis

    12/29/2007 1:21:00 PM |

    Yes. Unfortunately, now several studies have shown that there is greater heart valve and artery calcification with prolonged Coumadin usage. Although the data are very preliminary, there may be benefit to K1 and K2 supplementation, though your doctor's cooperation is required to do this.

  • Harry35

    12/30/2007 1:38:00 AM |

    Here's a list of fermented and unfermented cheeses that I compiled by googling around. Not sure how to tell which of the fermented cheeses have the most K2, though.


    Aged goat cheese
    Bleu Cheese
    Cultured dry cottage cheese
    Port du Salut


    Farmer cheese
    Most cottage cheese
    Pot cheese
    Processed cheese

  • Dr. Davis

    12/30/2007 2:07:00 PM |

    Wow! Thanks, Harry.

    I didn't realize that provolone and ricotta were unfermented.

  • chickadeenorth

    12/30/2007 4:37:00 PM |

    Wow great info and timely article...thnx.
    I eat those fermented cheeses that  and have eggs, I use only olive oil though. I read somewhere that any oil that gets sticky on outside of the jug gets sticky inside the body and since canola is one of those I quit using it, wish I could find that article, ( Eades maybe?)what do you folks think.
    So having some oil on veg and salad is great, I don't use those low fat or spritz things are they seem too processed and full of chemicals.

    Thnx Dr D for the excellent info as always.

    So do you eat those slimy soybeans, are they pretty icky or do you think a person could get used to them. Lots of my Japanese guests ( from Japan not North America) bring some of their own food and I have seen these before. Looks kind of like eatin the foods off Fear Factor....j/k.

  • MAC

    12/30/2007 4:48:00 PM |

    Seem to remember reading somewhere recently that if the cheese has the word "culture" in the ingredient list then it is a fermented product. This could mean yogurt and kefir may have K2. Web sources seem to indicate this but didn't find any I consider reliable.

  • Dr. Davis

    12/30/2007 10:54:00 PM |

    I don't think that there's anything wrong with actually eating natto. It's just that it is quite difficult to stomach. I had it several times as a kid and found it thoroughly unappetizing, despite having tried some really exotic stuff like raw octopus and seaweed. Natto was the one thing I simply could not eat.

    The stick oil thing has me stumped. Our bodies digest foods like oil before they make it into the blood stream. Why its behavior in a bottle would have any bearing on its behavior in the body is beyond me.

  • Cindy Moore

    12/31/2007 12:08:00 AM |

    Mary Enig is an excellent source of information about oils. Her general belief is that processed oils (like corn, cannola and soy) are heat treated during the processing and this heat damages the fat molecules, so these fats are essentially spoiled when they are bottled. These oils are also polyunsaturates, which are the least stable of oils, so they should be stored properly and protected from heat, light, etc. (Flax and fish oils are "good" polys, but care should be used to keep these fresh and prevent oxidation)

    I only use virgin olive oil, virgin cocount oil and butter, and I rarely (if ever) use olive for cooking. (I want to try the nut oils, but haven't given them a shot yet).

  • chickadeenorth

    12/31/2007 8:20:00 AM |

    Cindy why don't you use olive oil to cook in at low heat,curious, I thought that was ok if it didnt get too hot. I just got some walnut and almond oil and have to try them.I also use coconut oil to cook in and grapeseed for salads.

    I cannot get vit k 2 in Ca and have a friend going to Florida in 2 days who will buy me some, what is a good name brand and dose,  also a good name brand and dose for DHEA thanks for feedback.

  • Cindy Moore

    12/31/2007 5:51:00 PM |

    chickadeenorth, I don't often us olive in cooking because I've read (Enig I believe) that if it smokes it shouldn't be eaten....and I've had too many instances of the heat getting ahead of me and the oil ending up burned. I just find it easier to use coconut....and then I add butter and/or olive oil at the end to give it flavor, if needed. Mostly I just use the coconut oil.

    I use Source Naturals K, but am also interested in hearing some recommendations. I bought this because I'm told Source Naturals is a good company.

  • Dr. Davis

    12/31/2007 6:10:00 PM |

    We've used Source Naturals, Life Extension, and Jarrow. All seem like the real thing.

  • chickadeenorth

    12/31/2007 8:40:00 PM | this in dry tablet form, what dose of tablet should I get her to pick up, what about DHEA?? name brand and dose.

    Ya I cook with natural gas so keep flame very low and don't over heat anything,I don't use allot as have good pots, maybe should use coconut more often, its adds a nice flavor especially to chicken and pork.

    I think some guests from Japan bought some of those soybeans once in a can, is that how they come, they ate something that looked familiar to your picture.

  • g

    1/1/2008 6:35:00 AM |

    Apparently the ADA have new guidelines coming soon!  AND guess what they advise now!  LOW CARB diets!!

    This is funny...

  • chickadeenorth

    1/1/2008 5:13:00 PM |

    Hmm wonder what pushed their buttons, the powers at be in USA are also supposedly going to recommend a higher dose of Vit D too.

  • brassman

    1/1/2008 6:04:00 PM |

    Vitamin K is fat soluble. Will a tablet be absorbed well or do I need a soft gel as with vitamin d?

  • chickadeenorth

    1/1/2008 9:06:00 PM |

    Is this the right DHEA I am looking for, if so I found a source in Canada but still no Vit k 2.Sorry I can't log onto the forum.Smile

  • Dr. Davis

    1/2/2008 12:10:00 PM |

    The label and info says phosphatidylserine, not DHEA.

  • Dr. Davis

    1/2/2008 12:11:00 PM |

    The data would suggest that, unlike vitamin D, even tablets of K2 are well absorbed.

  • Anonymous

    1/31/2008 1:02:00 AM |

    Hello Dr. Davis,
    Thank you for this great post. We've recently learned that K2 was probably what Weston Price had  called Activator-X, since he had not been in contact with other researchers who were learning about vitamin K at the time.

    Anyway, I can help with the "sticky oil" comment. Oils that oxidize easily become sticky (basically like varnish drying) when exposed to oxygen. This means that canola oil and other less-saturated fatty acids can oxidize (producing free radicals) in the bottle (and MAYBE in the blood - there is oxygen in the blood, but I'm not an expert in blood chemistry). We don't know how long the oil was exposed to air before it was bottled. X-virgin olive oil, on the other hand, has a lot of anti-oxidants built in (and numerous phyto-nutrients), so probably has a longer shelf life. Most Canola oil is a highly processed modern hybrid. The Mediterranean people never lived on Canola oil. The fact that both are monounsaturated is largely irrelevant.  -David

  • Dr. Davis

    1/31/2008 1:33:00 PM |

    Thanks for the help, David.

  • donny

    7/1/2008 6:23:00 PM |

    I hate to comment on an article this old, but I've been reading a lot of stuff online about vitamin k lately. I found this article recently. Really, it looks like an attempt to denigrate food sources of vitamin k in comparison to supplementation.
    First they compared spinach consumption to a vitamin k supplement called konakion, and showed that konakion raised serum levels of k1 maybe seven to eight times as much as 227 grams of boiled spinach with butter. Then, they did a bait and switch, comparing the spinach and butter to a milligram of k2 mixed with 5 grams of butter, and they have a chart with that showing that the k2 with butter raised serum levels of k2 twice as much as the spinach with twenty five grams of butter.
    I'm just wondering if green vegetables, with butter, might be a good way to raise k2 levels after all?

  • Anonymous

    12/2/2008 3:05:00 PM |

    "Why would humans have developed a need for a nutrient that is created through fermentation with only small quantities in meats and other non-fermented foods?"

    Perhaps this is an example of how our "sterile" environment is killing us.  Before refrigeration, I am sure humans were subject to much more fermented food.

  • Dane Miller

    4/20/2009 5:58:00 PM |

    I , too hate commenting on an article so old.  Great stuff but canola as a healthy oil?  I think not.  Canola is terrible for you.  Or should I said rapeseed oil.

  • jpatti

    5/25/2009 1:05:39 AM |

    I understand there's a good bit of K2 in unpasteurized milk.  Apparently, grass-fed animals do produce a lot of A, D and K2, but much is destroyed through pasteurization.

    I've recently added raw milk to my diet.  Decided it was worth taking extra insulin for the health benefits.  Can't get raw butter or cream in my state, but am getting it from the same dairy, so it's grass-fed if not raw.

    My bp has dropped about 30/30 without the Lisinopril I was on before.  As hubby says, if it's placebo, it's one worth sticking to.  ;)

    Besides raw milk, I've also about tripled my intake of butter and eggs.  

    And btw, fermenting raw milk yourself is wicked easy.  Take a quart of milk, heat it to around 100-110 degrees (I do this with a quart jar in my crockpot in an inch of water with the lid off).  Remove about a half cup of warmed milk and stir in about 1/4 cup yogurt.  Pour this back into the main container, turn off the crockpot (so it doesn't overheat and kill the culture), and cover with a blanket or such to insulate it.  

    I do this while fixing dinner, in the morning I have yogurt - fermented raw milk, yummy stuff, chockful of K2.  It's not thick like store-bought, more like a drink.  I add blueberries to it most often.

    The point is, with a source of raw milk it takes about 5-10 minutes of "work" to make your own fermented dairy.  You need a quart sized jar, a source of heat, a thermometer, some insulation and some culture (store-bought plain yogurt works fine) - fermented dairy just happens overnight.

  • robbyn

    9/27/2009 9:44:19 AM |

    I know that sauerkraut contains vit k2, but do not know how much per 100g. Has anyone been able to find the figures?

  • Anonymous

    1/5/2010 5:13:32 PM |

    Dear Dr. Davis
    Is there a special food diet for patients with aortic valve calcification. How many milligrams
    of vitamin CaLaughing:K2:K:Mg, are recommended for patients.

  • Sharon

    2/17/2010 6:56:22 AM |

    Serious question Dr.Davis:    Fibrinogen can create calcification, K2 reduces calcification, natto reduces fibrinogen but is there any clottin risk and conflict in using both agents for a patient with the two dysfunctions?

    Thank you Sharon

  • Anonymous

    3/15/2010 8:46:14 PM |

    Recently had a CT.  After the CT, got up off table and had no pain for 2 weeks.  In constant pain due to significant cervical and lumbar radiculopathy, fibromyalgia, osteoarthritis, etc.  Has anyone ever had a CT with contrast who was in pain and pain gone after the contrast CT?  My doctor told me to blog to see if could find others who drank a liquid and had an IV during the CT.  Was wonderful to have no pain for 2 weeks, and interesting it happened immediately upon rising from the table where the CT was performed.  Anyone exeriencing this, please blog

  • ea

    3/25/2010 1:35:56 AM |

    In it says:
    Since the amount of vitamin K1 in typical diets is ten times greater than that of vitamin K2, researchers have tended to dismiss the contribution of K2 to nutritional status as insignificant. Yet over the last few years, a growing body of research is demonstrating that these two substances are not simply different forms of the same vitamin, but are better seen as two different vitamins: whereas K1 is preferentially used by the liver to activate blood clotting proteins, K2 is preferentially used by the other tissues to place calcium where it belongs, in the bones and teeth, and keep it out of where it does not belong, in the soft tissues.
    In other words, to properly use the Calcium in your diet, you need vitamin K2 (as well as A & D) ~ and, since K2 is fat soluble, also fat so that you can absorb the K2.  With K2 the Calcium will be used to strengthen bones and teeth. Without K2 the Calcium will be deposited in joints leading to osteoarthritis, in blood vessels leading to heart attacks and strokes, in eyes leading to cataracts, and in other soft tissues.

    In there is also a table of K2 content of various foods.

  • bed frame

    7/6/2010 7:09:17 AM |

    Before I don't know what is vitamin K2 is. But after reading and analyzing your post. Now I know that it is important. I thank you for sharing this very helpful post.

  • Yogi Sinzapatos

    7/29/2010 3:50:33 PM |

    Mixing jpatti's home made raw milk yogurt with flaxseed oil = Dr. Johanna Budwig's cure for cancer (and many other diseases).

  • dermatology laser

    9/30/2010 3:23:32 AM |

    Vitamin K2 might be, for instance more relevant in the form of a supplement or in low-fat dairy.

  • Chuck

    10/21/2010 3:38:37 AM |

    As far as Warfarin blocking the absorption of vitamin K, I am not a big fan of people taking rat poison. Warfarin is the active ingredient in rat poison.

    It is worse than the urine of a pregnant horse. Premarin-- pregnant mare urine. I am American and natto does not taste that bad. Of course it is better to add it to something else. For example no one eats sugar by itself.

    Now raw garlic by itself is painful to eat. But I add it to other foods and it is OK. Raw ginger by itself is also painful to eat.

  • buy jeans

    11/3/2010 4:53:24 PM |

    MK-7 and MK-8,9,10 come from bacterial fermentation, whether in natto, cheese, or in your intestinal tract; MK-4 is naturally synthesized by animals from vitamin K1. While natto is the richest source of the MK-7 form, egg yolks and fermented cheeses are the richest sources of the MK-4 form.

  • Heidi

    11/11/2010 5:34:36 PM |

    Earlier in the thread there was mention made on canola oil. Here's a link that explains the dangers:

  • Jack C

    11/18/2010 3:03:20 AM |

    Somewhere in my files there is a study, from Japan I believe, that found that serum concentrations of MK4 increased after consumption of natto, which contains no MK4. It therefore appears that MK7, 8 and 9 will convert, to some degree, to MK4. Conclusion (mine): Aged cheese can provide all of the vitamin K2 needed. Aged raw milk cheese has most of the benefits of raw milk but is as pathogen free as pasteurized milk due to destruction of pathogens by low pH during aging.  

    While I can not quickly lay my hands on that study, I have found a couple of other related studies of interest.

    Vitamin K is required for activation of osteocalcin. Vitamin K deficiency is associated with low bone mineral density due to increased levels of uncarboxylated (unactivated) osteocalcin(ucOC). The plasma vitamin K2 concentrations required to minimize ucOC increases with age (PMID 16469998). Conclusion: (mine) Eat more aged raw milk cheese as you age to protect you bones.

    Rats readily convert vitamin K1 to K2 but humans do not.

    "Vascular calcification may be species specific to humans. As laboratory animals, such as the rat, grow old, they suffer from only mild arterial calcification" (PMID 18772323): Conclusion (mine): K2 is the answer: Eat more raw milk aged cheese as you get older to prevent calcification of arteries.

    Jack C.

  • Gillian

    1/17/2011 5:13:44 PM |

    Hi, Dr Davis
    I´ve read in some earlier comment of yours, that natto is not really a reliable source for K2, is that so and if, then why?
    I also wonder why I sometimes feel pain in my legs when eating cream.
    I have seen the famous photographer from Sweden that have filmed arteries and showed that cream supposedly block the arteries..
    What is your opinion??

  • Lobster bake

    2/18/2011 9:17:08 AM |

    Thanks, very well written post, found it through a random Google search and I shared it on my Facebook. This Vitamin K foods are very helpful to keep our body healthy and young.