Vitamin K2: The Missing Nutrient

cheeseA study recently published by the European Prospective Investigation into Cancer and Nutrition (EPIC) has revealed that increased intake of vitamin K2 may reduce the risk of prostate cancer by 35 percent. The authors point out that the benefits of K2 were most pronounced for advanced prostate cancer, and, importantly, that vitamin K1 did not offer any prostate benefits.

The findings were based on data from more than 11,000 men taking part in the EPIC Heidelberg cohort. It adds to a small but fast-growing body of science supporting the potential health benefits of vitamin K2 for bone, cardiovascular, skin, brain, and now prostate health.

Unfortunately, many people are not aware of the health benefits of vitamin K2. The K vitamins have been underrated and misunderstood up until very recently in both the scientific community and the general public.

It has been commonly believed that the benefits of vitamin K are limited to its role in blood clotting. Another popular misconception is that vitamins K1 and K2 are simply different forms of the same vitamin – with the same physiological functions.

New evidence, however, has confirmed that vitamin K2′s role in the body extends far beyond blood clotting to include protecting us from heart disease, ensuring healthy skin, forming strong bones, promoting brain function, supporting growth and development and helping to prevent cancer – to name a few. In fact, vitamin K2 has so many functions not associated with vitamin K1 that many researchers insist that K1 and K2 are best seen as two different vitamins entirely.

A large epidemiological study from the Netherlands illustrates this point well. The researchers collected data on the vitamin K intakes of the subjects between 1990 and 1993 and measured the extent of heart disease in each subject, who had died from it and how this related to vitamin K2 intake and arterial calcification. They found that calcification of the arteries was the best predictor of heart disease. Those in the highest third of vitamin K2 intakes were 52 percent less likely to develop severe calcification of the arteries, 41 percent less likely to develop heart disease, and 57 percent less likely to die from it. (Geleijnse et al., 2004, pp. 3100-3105) However, intake of vitamin K1 had no effect on cardiovascular disease outcomes.

While K1 is preferentially used by the liver to activate blood clotting proteins, K2 is preferentially used by other tissues to deposit calcium in appropriate locations, such as in the bones and teeth, and prevent it from depositing in locations where it does not belong, such as the soft tissues.(Spronk et al., 2003, pp. 531-537) In an acknowledgment of the different roles played by vitamins K1 and K2, the United States Department of Agriculture (USDA) finally determined the vitamin K2 contents of foods in the U.S. diet for the first time in 2006. (Elder, Haytowitz, Howe, Peterson, & Booth, 2006, pp. 436-467)

Another common misconception is that human beings do not need vitamin K2 in their diet, since they have the capacity to convert vitamin K1 to vitamin K2. The amount of vitamin K1 in typical diets is ten times greater than that of vitamin K2, and researchers and physicians have largely dismissed the contribution of K2 to nutritional status as insignificant.

However, although animals can convert vitamin K1 to vitamin K2, a significant amount of evidence suggests that humans require preformed K2 in the diet to obtain and maintain optimal health. The strongest indication that humans require preformed vitamin K2 in the diet is that epidemiological and intervention studies both show its superiority over K1. Intake of K2 is inversely associated with heart disease in humans while intake of K1 is not (Geleijnse et al., 2004, pp. 3100-3105), and vitamin K2 is at least three times more effective than vitamin K1 at activating proteins related to skeletal metabolism. (Schurgers et al., 2007) And remember that in the study on vitamin K2′s role in treating prostate cancer, which I mentioned at the beginning of this article, vitamin K1 had no effect.

All of this evidence points to the possibility that vitamin K2 may be an essential nutrient in the human diet. So where does one find vitamin K2 in foods? The following is a list of the foods highest in vitamin K2, as measured by the USDA:

Foods high in vitamin K2

  • Natto
  • Hard cheese
  • Soft cheese
  • Egg yolk
  • Butter
  • Chicken liver
  • Salami
  • Chicken breast
  • Grond beef

Unfortunately, precise values for some foods that are likely to be high in K2 (such as organ meats) are not available at this time. The pancreas and salivary glands would be richest; reproductive organs, brains, cartilage and possibly kidneys would also be very rich; finally, bone would be richer than muscle meat. Fish eggs are also likely to be rich in K2.

It was once erroneously believed that intestinal bacteria are a major contributor to vitamin K status. However, the majority of evidence contradicts this view. Most of the vitamin K2 produced in the intestine are embedded within bacterial membranes and not available for absorption. Thus, intestinal production of K2 likely makes only a small contribution to vitamin K status. (Unden & Bongaerts, 1997, pp. 217-234)

On the other hand, fermented foods, however, such as sauerkraut, cheese and natto (a soy dish popular in Japan), contain substantial amounts of vitamin K2. Natto contains the highest concentration of K2 of any food measured; nearly all of it is present as MK-7, which research has shown to be a highly effective form. A recent study demonstrated that MK-7 increased the percentage of osteocalcin in humans three times more powerfully than did vitamin K1. (Schurgers & Vermeer, 2000, pp. 298-307)

It is important to note that commercial butter is not a significantly high source of vitamin K2. Dr. Weston A. Price, who was the first to elucidate the role of vitamin K2 in human health (though he called it “Activator X” at the time) analyzed over 20,000 samples of butter sent to him from various parts of the world. As mentioned previously in this paper, he found that the Activator X concentration varied 50-fold. Animals grazing on vitamin K-rich cereal grasses, especially wheat grass, and alfalfa in a lush green state of growth produced fat with the highest amounts of Activator X, but the soil in which the pasture was grown also influenced the quality of the butter. It was only the vitamin-rich butter grown in three feet or more of healthy top soil that had such dramatic curing properties when combined with cod liver oil in Dr. Price’s experiments and clinical practice.

Therefore, vitamin K2 levels will not be high in butter from grain-fed cows raised in confinement feedlots. Since the overwhelming majority of butter sold in the U.S. comes from such feedlots, butter is not a significant source of K2 in the diet for most people. This is yet another argument for obtaining raw butter from cows raised on green pasture.

New research which expands our understanding of the many important roles of vitamin K2 is being published at a rapid pace. Yet it is already clear that vitamin K2 is an important nutrient for human health – and one of the most poorly understood by medical authorities and the general public.

Recommended links

  • On the Trail of the Elusive X-Factor
  • The Vitamin You Need to Prevent Prostate Cancer
  • K2 Associated with Reduced Risk of Coronary Heart Disease

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  1. veronica’s avatar

    Hi Chris,I am in the process of getting dental implants but the bone graft I had done 4 months ago is not hardening as I hoped and was wondering if k2 with d3 would help.
    Thank you

  2. Chris Kresser’s avatar

    I imagine it would, since K2 regulates calcium metabolism and directs it to the bones and teeth rather than the soft tissues.

  3. ben nguyen’s avatar

    Natto (fermented soy beans) would seem like the perfect source for vitamin k2…   However, isn’t soy particularly bad?
    I’m guessing blood tests could be done to check k2 levels.. what would be a healthy number to shoot for?

  4. Chris Kresser’s avatar

    Unfermented soy is bad.  Fermented soy is fine in moderation.  Natto is indeed the best source of K2, but most people can’t tolerate the taste.

    I haven’t heard of a reliable blood test for K2.

  5. ben nguyen’s avatar

    Tried natto, didn’t like the taste :(
    Did find perhaps some k2 source alternatives:

  6. Chris Kresser’s avatar

    Either of those would be fine. Thorne and GP are both good companies.

  7. ben nguyen’s avatar

    Neither has K2 in the MK7 form that comes from fermentation (natto etc)… they both contain K2 of the MK4 type (i.e. K2 that’s been synthesized by animal tissues)
    So that begs the question, which is better MK4 vs. MK7?
    Jarrow for example has an MK7 supplement:
    Interesting Study cited in this thread:

  8. Chris Kresser’s avatar

    That’s a controversial topic, Ben. MK4 is the form synthesized from K1 by humans for their own use. Although they’re similar in function, MK-4 has effects on gene expression in bone tissue that MK-7 doesn’t have. I recommend using MK4 for this reason. See this post for more information.

  9. ben nguyen’s avatar

    Yes, according to that great post, it does seem that the effective of MK-7 has not been studied yet…
    The comments to the post were also great, someone pointed out that Life Extension has one product with both MK-4 (1mg) and MK-7 (1ug)!  So I think that might be a good way to hedge my bet!

  10. Patti Hill’s avatar

    Hi Chris,
    I am thinking of adding K2 to my vitamin regimen.   I have been taking over the counter calcium with vit. D for over 30 years which was prescribed when I had lupus.  It has been gone for 20 years but I still take calcium for mild osteopenia.   Over the years, I have developed many calcium deposits in my thighs and torso.  The doctors say it is nothing to worry about and they have no answer as to how to stop them or get rid of them.  Do you think the K2 might possibly help to get rid of the calcium deposits or keep new ones from occuring.  Also I eat a lot of store made saurekraut, not canned.  It is considered fermented?  I also eat 8-10 Egglands free range eggs a week.  Do you think the sauerkraut and eggs might provide enough K2 without the need to supplement? 
    Thanks for any advice.


  11. Chris Kresser’s avatar


    Sauerkraut must be raw in order to be of benefit. The stuff they sell in normal supermarkets is pasteurized, which kills the beneficial bacteria. Health food stores in many areas do sell raw sauerkraut, or even better, you can make it yourself and save a ton of money.

    Eggs – even “free-range” supermarket eggs – are not as high in K2 as some fermented foods like natto and hard cheese. Butter is another good source, but it must come from grass-fed cows, and that’s not easy to find in some places.

    With your history you might consider the fermented cod liver oil / butter oil blend from Green Pastures. It has vitamin D, vitamin A and vitamin K2 as well as EPA and DHA together. It’s actually one of the few maintenance supplements I recommend everyone take, because of the balance of nutrients it contains. A, D & K2 work synergistically to promote healthy bones.

  12. Patti Hill’s avatar

    Thanks Chris.  I will look at their website.  You say this one of the few supplements you recommend everyone take.  Are there others and, if so, what? 

    On a totally unrelated issue, I have had low WBC counts for the last 10 years, possibly more, and it is low enough that doctors wanted to find a cause but, as yet, have not found one.  Do you have any knowledge on this?  My internet searches have not helped me and I’m not sure I should even be too concerned about it.  One person said that low WBC are not a diagnosis but simply a lab result that might have meaning, so don’t worry about it.   Do you have any thoughts?


  13. Chris Kresser’s avatar

    It depends on the person.  For the average, generally healthy person the fermented cod liver oil / butter oil blend is it.  Magnesium is difficult to get with a paleo/primal type diet, which is often what I suggest people follow, and many people are deficient in it so I may suggest that as well.  Overall my preference is always to obtain the nutrients we need from food, or at least food-based products like cod liver oil, when possible.

    Low WBC may indicate a chronic viral or bacterial infection, or it may simply be genetic.  If you’ve low WBC your whole life, and you aren’t symptomatic, I wouldn’t worry about it.

  14. Linda’s avatar

    I’ve just come across your site & this thread on K2. I wonder if you’d share you thoughts on a a bit of a challenge we face at times in my health food store — how to best inform people who are taking blood-thinning drugs about the benefits of K2. We now just suggest that they ask their doctor about how to balance the K2 & the warfarin. We realize of course that virtually no PCP’s are informed on this.
         I myself take K2 & D3 daily, to help stop my body from taking calcium from my bones & then depositing it in joints, etc.

  15. Chris Kresser’s avatar

    There are studies demonstrating that rats treated with high doses of warfarin develop arterial calcification, and that K2 protects against this. It can be speculated that humans who take warfarin also develop some degree of calcifications in their arteries, predisposing these patients to heart attacks and strokes. Unfortunately I haven’t seen human studies confirming this. On the other hand, the Rotterdam Study showed that K2 intake is associated with a significant reduction in CVD. And this study shows that K2 does prevent arterial calcification. So, although we don’t yet have all of the research we’d like to have on this subject, I think you can piece together a pretty strong argument for taking K2 with warfarin. The caveat is that K2 will probably lower the INR to some degree, so the PCP would need to monitor that.

    You could also educate them on using EPA & DHA at high doses as an alternative to warfarin. Studies have shown similar CVD-preventative effects, and of course EPA & DHA have benefits warfarin doesn’t have.

  16. ben nguyen’s avatar

    A synthetic k2 (mk-7 only) that is more absorbable?

  17. Jane’s avatar

    I am on a Calcium, Vitamin D supplement for thinning bones. It also has 45mcg of vitamin K2. Does this cause blood clots, since that what I understand vit K does? 

  18. Chris Kresser’s avatar

    Vitamin K2 and vitamin K have different effects. K2 primarily regulates calcium metabolism (i.e. makes sure calcium goes into the bones and teeth where it belongs and not the soft tissue), whereas vitamin K has a stronger effect on coagulation.

  19. Ann’s avatar

    Chris, thanks for your information on K2.  I am researaching benefits of K2 for my situation.  I did not have osteoporosis until I had been on Advair for a few years for COPD from chronic bronchitis.  I have been on Actonel for 1 yr and 7 months.  Just had a bone density test that showed I have declined again, 12%.  Now at -3.3.  I have taken calcium supplements for most of my adult life and have been taking D3 and magnesium for several years.  I have a history of DVT, so I take Persantine, which is not a blood thinner, but keeps my platelets from sticking together.  I transitioned to vegan and have been free of animal products for one year.  I do not eat the high fat raw, but try to eat mostly fruit, veggies, legumes, and small amount of whole grains and try to keep fats low (nuts and EVO).  I am wondering if 1) K2 is right for me,  2)  if my diet contributed to the bad report,  3) would K2 help if I still have to take Advair (steroids).  Would Kefir have K2?  What about rejuvalac?

  20. Chris Kresser’s avatar

    Ann: I don’t advocate a vegan diet for multiple reasons, and this is one of them. It’s impossible to get the nutrients (from food) necessary for optimal health with a vegan diet. I’ve written about that elsewhere on the blog. My recommendation for dealing with your problem would include a diet rich in grass-fed animal products, fermented cod liver oil (supplying A, D, K2, E and other quinones in their natural, whole-food form), and regular consumption of whole, fatty fish like salmon. K2 is certainly right for you, as is a whole-food form of D and A. Kefir probably does have some K2, since it’s fermented – especially if made with milk from grass-fed cows. Sauerkraut is another potential source.

  21. Ann’s avatar

    Chris, thank you for you reply.  This info has helped.  I will make diet changes.  I know that I am not getting enough calories with vegan diet, but in going low-fat vegan, I was trying to lower cholesterol which has been high for years; plus, acidic animal foods supposedly make osteooporosis worse.   I am allergic to seafood, so can’t do fish or cod liver oil.  I do have Ann Wigmore’s books with instructions on how to make sauerkraut.  It is not easy  to find the right way to eat to obain better health.  This blog has offered more information that just reading an article would not provide.  Thanks again!

  22. Chris Kresser’s avatar

    There’s no need to lower cholesterol in most cases.  Read these articles and watch the videos.

  23. jackie’s avatar

    Hello, Chris! I just started taking the TriK Vitamin K supplement, and was wondering if the multi-vitamin that I am taking offers sufficient D3 (5,000 IU) and A (5,000 IU) to aid in absorption? I also take a Krill Oil supplement once daily. I am taking the supplement becuase I am genetically predisposed to heart problems and osteoperosis (both sides of the family) – I am 30 but don’t want to take any chances with problems down the line. Just wondering if this is a good idea? Thanks for your time!!

  24. Chris Kresser’s avatar

    You should be fine. I prefer getting A & D from natural, whole food sources like fermented cod liver oil (from Green Pasture), but in terms of dosage you’re fine with 5,000 IU of both.

  25. jackie’s avatar

    Awesome! Thanks for your reply! Would the fermented cod liver oil replace the Krill Oil? And, if I switched to that could I still take my multi-vitamin? The multi-vitamin is a whole food one.

  26. Chris Kresser’s avatar

    Yes, it would replace the krill oil.  I’m not big on multivitamins.  Read why.

  27. jackie’s avatar

    Great, thanks again for the information!! :)

  28. Pingback from If I Were Still a Vegetarian… | Critical MAS on September 11, 2010 at 8:22 pm

  29. Tricia’s avatar

    Dear Chris
    I take Strontium Ranelate for osteoporosis.  As I’m sure you are aware, it has an uncommon side effect (1 to 10 in 1000) of blood clots.  I would like to take K2 but wonder if it would be contra-indicated with the strontium as K2 clots blood –  doesn’t it?
    If appropriate, what dose?
    Can you advise?   Many thanks.

  30. Chris Kresser’s avatar

    Although high doses of K2 can lead to hemorrhaging, high doses of K2 don’t necessarily lead to increased clotting if the dose is ramped up carefully. Because vitamin K2 activates both pro-coagulation and anti-coagulation factors in parallel, high serum levels of vitamin K2 are generally consistent with normal blood clotting.

    K2 is extremely important for bone health and prevention of arterial calcification. Seven clinical trials studying K2 supplementation at 45 mg/day consistently observed reduced fracture rates. On average, K2 supplementation reduced the risk of vertebral fractures by 60%, hip fractures by 77%, and non- vertebral fractures by a remarkable 81%.

    Print out these studies and take them in to your doctor and see what he/she thinks.

  31. Tricia’s avatar

    A recent DEXA scan showed that I had “quite a lot” of calcium in my system.  Does this mean that I am absorbing the calcium supplements I take (i.e. not eliminating them in urine), but it is being deposited in the wrong place?
    I have begun to take K2 but wonder if it should be taken away from the calcium supplements in order to allow it to take action on the unwanted deposits.
    Should I reduce the calcium?  I take 650 mg together with magnesium, D3 etc.
    Finally are you aware of any reports of insomnia with higher doses of K2?
    I’d be very grateful for any enlightenment.   Many thanks.

  32. Chris Kresser’s avatar

    I’m not a fan of calcium supplementation, and your issue is one of the main reasons.

    You should not have calcium in your soft tissues.  K2 and vitamin D both regulate calcium metabolism, so you should definitely be normalizing your levels of both.

    I’ve never heard of K2 causing insomnia and can’t figure out any mechanism that could explain it.

  33. Anna’s avatar

    Is it safe for someone on warfarin sodium / coumadin to take Garden of Life Raw Meal once a day everyday ? As I would like to incorporate into my morning smoothies to get nutrients I need as I don’t get all the nutrients listed on the nutritional label.

    It has Vitamin K2 in it in the form of Raw MK-7 at 80mcg ( 100% daily value ) ? Is 80mcg enough to benefit as I was said to have osteoporosis I am only twenty something ? Should I avoid Vitamin K1 that is in the Vega Health Optimizer ?

    I do appreciate replies.

  34. CJ’s avatar

    I’m 37 and I recently had a brief bout with heart palpitations (they’ve since gone away), and an Echocardiogram showed a small amount of mitral calcification.  Since the palpitations had gone away and I had no other symptoms, the cardiologist said no other action or follow up was necessary.  I did some reading and began supplementing my diet with 150 mcgs of MK-7 K2 from Jarrow. 
    Any hope that the K2 may help “de-calcify” my mitral valve and leaflets?

  35. Chris Kresser’s avatar

    K2 has been shown to reverse arterial calcification in some people.  So yes, it has that potential.

  36. Myrna James’s avatar

    Hi Chris,
     Recently on  I read a great article on K2 in the treatment of this disease …a Phase II trial.  i have a friend with this and after stopping a tough drug that didn’t work…  Revlimid. she showed her Dr. the article and now she is doing  15 mgX3 daily and Vit D3 at 5000 Iu/day + some B12.   Her RBC indices are back to normal and she is hoping to extend the time between transfusions.
     I found a source of K2 15mg at Vitamin Research Lab in Nevada. Her Dr. ok’d her
    to try this for 3 months.
      Any comment?  Other Vit K2 sources better?

  37. Chris Kresser’s avatar

    I’m not too picky about vitamin K2 supplements, though I prefer to get as much of it from food as possible.  I explain how to do that in the article.

  38. Tiffany’s avatar

    I recently read an article in a news paper a week ago about vitamin K2 and its benifits with removing calcium from the arteries and placing the ca to bone.  The vitamin they were promoting was the “king of all calcium” because it included calcium, D3, mag, and K2 from the natto bean.  I have been reading your information about how K2 from natto bean needs to be fermented.  Would this be something to ask that company and its article if the vit D3 thats from the natto bean is fermented? Thank you

  39. Chris Kresser’s avatar

    Natto is fermented as a rule, so I doubt you have to ask about that.

  40. ben’s avatar

    I believe the product you are probably referring to is,
    which has 100mcg of the non-fermented k2 type (menatetrenone (mk-4)).  If you’re looking for vitamin k2 that comes from natto, look for it in the ingredients as: menaquinone (mk-7).  I posted a comment above for example products.

  41. Tiffany’s avatar

    I received the product its called Intellikal plus ( Vitamin D3 1000IU, MenaQ7- (as menaquinone 7) 45mcg,  Calcium  (from calcium citrate) 400mg, Magnesium (from magnesium citrate) 200mg.  4 capsules a day. This product has less amount of K2, Calcium and magnesium compared to Natures plus.  Curious what is a balanced amount?

  42. Chris Kresser’s avatar

    I’m not a fan of calcium supplementation. 2,000 IU of D3 is probably good for maintenance, and 200 – 300+ mg of magnesium (depending on needs/goals) is good. Most Americans don’t need to supplement with calcium. They need K2, calcium and magnesium to put the calcium where it belongs – in the teeth and bones – rather than in the soft tissue.

  43. anonymous’s avatar

    Dear Chris nice site. I was recently diagnosed with mild MS, I had very low levels of vit D but have been supplementing with d3 both with solgars cod liver oil and Thornes d3 powder supplement, i am concerned after reading weston price that my A to D levels are out of wack and as I have mild osteopaenia I am also worried about how to safely calcium supplement as Im aware that magnesium becomes a real issue for me with noise sensitivity and jumpiness. I do take a multi by Thorne which I rotate with a B group. Im thinking of starting fermented cod and butter oil, but would love to get some personal feedback and reviews [beside weston price]as to its effectiveness. Also with multis and the research into beta carotene, vit e etc, wasnt it a case of artificial beta carotene and only testing D-Alpha tocepherol rather than the multitude of tocepherols that occur in nature?

  44. Chris Kresser’s avatar

    Hi anonymous,

    Overall I think vitamin D, magnesium & K2, as well as regulating cortisol and blood sugar levels, are more important for maintaining bone health than calcium supplementation – which can be dangerous in the absence of those other factors.

    FCLO/butter oil blend is the best product I’m aware of for fat-solube vitamin needs. It’s extremely effective, and a very high quality product. I use it with nearly all of my patients, and I take it myself.

    Yes, the research shows that synthetic vitamins and antioxidants are either not beneficial, or even harmful. That’s why it’s so important to get our nutrients from real food.

  45. Tiffany’s avatar

    I would love to hear more about regulating cortisol levels. Would this effect your sleep and weight

  46. Pingback from Is Butter Healthy? Part 3: Vitamin K2 Benefits | on November 17, 2010 at 7:33 am

  47. Ron’s avatar

    Recommend dosage of k2 to be effective for clearing arteries of plaque.

  48. Lounett Holloway’s avatar

    Hi Chris,

    Great blog about K2! After read the wonderful benefits of K2 I am planning on take it . May God continue to bless you?

    Lynette (Nickmane)

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