A streamlined stack of supplements designed to meet your most critical needs - Adapt Naturals is now live. Learn more

Vitamin K2: The Missing Nutrient

by

Last updated on

This bowl of natto is a good source of vitamin K2.

The role K2 plays is still not entirely understood, but research suggests that a nutrient deficiency of this vitamin can have far-reaching consequences for your health.

A study published by the European Prospective Investigation into Cancer and Nutrition (EPIC) revealed that increased intake of vitamin K2 may reduce the risk of prostate cancer by 35 percent. (1) 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 prostate health.

What Are the Benefits?

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

Vitamin K2 can help you maintain cardiovascular health, improve your skin, strengthen bones, and promote brain function. Find out more about this powerful nutrient.

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 the K2 vitamin’s role in the body extends far beyond blood clotting. It may help stave off chronic disease by:

K2 isn't the only vitamin you need for healthy skin

Download this free eBook to find out how dietary changes can restore clear, beautiful skin.

"*" indicates required fields

I hate spam, too. Your email is safe with me. By signing up, you agree to our privacy policy.

What Does It Do?

The K2 vitamin has so many functions not associated with K1 that many researchers insist that K1 and K2 are best seen as two different vitamins entirely.

Differences between Vitamins K1 and K2

A large epidemiological study from the Netherlands illustrates this point well. Researchers collected data on the vitamin K intakes of the subjects between 1990 and 1993. (2) They measured the extent of heart disease in each subject, who had died from it, and how this related to 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 K2 intakes were:

  • 52 percent less likely to develop severe calcification of the arteries
  • 41 percent less likely to develop heart disease
  • 57 percent less likely to die from it

However, intake of vitamin K1 had no effect on participants’ heart health.

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, like the soft tissues. (3) In an acknowledgment of the different roles played by vitamins K1 and K2, the United States Department of Agriculture (USDA) determined the vitamin K2 contents of foods in the U.S. diet for the first time in 2006. (4)

Like what you’re reading? Get my free newsletter, recipes, eBooks, product recommendations, and more!

Do We Need K2 in Our Diet?

A common misconception is that human beings do not need K2 in their diet, since they have the capacity to convert vitamin K1 to K2. The amount of K1 in typical diets is generally greater than that of 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 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 K2 in the diet is that both epidemiological and intervention studies show its superiority over K1. According to the epidemiological study from the Netherlands referenced above, intake of K2 is inversely associated with heart disease in humans, while intake of K1 is not. A 2007 study showed that K2 is at least three times more effective than vitamin K1 at activating proteins related to skeletal metabolism. (5) And remember that in the study on the K2 vitamin’s role in treating prostate cancer, which I mentioned at the beginning of this article, vitamin K1 had no effect.

Foods High in Vitamin K2

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

  • Natto, a soy dish popular in Japan
  • Hard cheese
  • Soft cheese
  • Egg yolks
  • Butter
  • Chicken liver
  • Salami
  • Chicken breast
  • Ground beef

It was once erroneously believed that intestinal bacteria played a major role in supplying the body with this vitamin. However, the majority of evidence contradicts this view. Most of the K2 produced in the intestine is embedded within bacterial membranes and not available for absorption. Thus, intestinal production of K2 likely makes only a small contribution to vitamin K status. (6)

While some foods like natto and hard cheeses are high in K2, many people don’t consume them regularly. This is where smart supplementation can play a role. When supplementing with K2, consider a product that contains a blend of MK-4 and MK-7 forms, which may have unique benefits.

ADAPT Naturals logo

Better supplementation. Fewer supplements.

Close the nutrient gap to feel and perform your best. 

A daily stack of supplements designed to meet your most critical needs.

Chris Kresser in kitchen

Fermented Foods Are a Good Source of K2

Fermented foods, however, such as sauerkraut, cheese, and natto, 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. One study demonstrated that MK-7 increased the percentage of osteocalcin in humans three times more powerfully than did vitamin K1. (7)

Butter and “Activator X”

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. (8) He found that the Activator X concentration varied 50-fold. Animals grazing on vitamin K-rich cereal grasses—especially wheatgrass 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 topsoil that showed 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.

We’re Still Learning about the Health Benefits of K2

New research that 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.

Affiliate Disclosure
This website contains affiliate links, which means Chris may receive a percentage of any product or service you purchase using the links in the articles or advertisements. You will pay the same price for all products and services, and your purchase helps support Chris‘s ongoing research and work. Thanks for your support!

437 Comments

Join the conversation

  1. 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.

  2. 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?

    Patti

  3. 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.

     

    • Patti,

      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.

  4. 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: http://www.jarrow.com/product/241/MK_7
     
    Interesting Study cited in this thread: http://www.imminst.org/forum/index.php?showtopic=25651

    • 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.

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

  5. 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.

    • The small amount of natto – a teaspoon a day – is easy to take. If anyone says they can’t eat that amount because of the taste, that is ridiculous as it is easy to mix with peanut butter, jam, … the list goes on.

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

  7. 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

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

  8. Great info on K-2. I’ve been diagnosed with bone spurs in neck, spine, shoulder and hip and have severe pain. I don’t know if the bone spurs can be dissolved, but the remodeling of the bone via calcuim, D-3 and K-2 should be most helpful shouldn’t it?

    I’m not keen on taking Natto, have heard that taken in natural form it’s totally nasty tasting. I think I’d go with Kefir, sauerkraut, and the other recommended foods. I have recently been drinking pristine raw milk from grass fed Jersey cows. Too soon to notice any difference in calcium increase.

    • You don’t want to drink milk, grass-fed, organic or not.

      Dairy proteins contain growth factors that make a baby calve gain 300 pounds in a few months.

      It’s the grass-fed dairy fat that benefits humans, with K2.

      Brie cheese, Gouda… grass-fed dairy cheeses and butters and fermented foods.

    • Barbara,
      I took “Acid-A -Cal” a vitamin to get rid of Bones spurs..

      I had one in my foot, and in my throat from a car accident many years ago.
      I don’t know why this works but it does.. I bought it from Amazon..

      I now take Throne Liquid K2 Mk-4 for my Osteoporosis.
      It takes the Calcium to your Bones and NOT your arteries.

  9. Does tempeh provide a similar K2 benefit as does natto, being a fermented product as well?

    • Natto is the only fermented soy product that contains a significant amount of K2.

  10. Since I have been taking Vit .K2 I am aware of a skin rash similar to hives.  Since my bones are deficient I have been taking an unusually high dose of K2 5000 mcg, Menatetrenone source.  I have read much information in your documentation but find no reference to  this subject.  Could you answer this concern for me.

    • I’ve never heard of hives as a response to high doses of K2, and I can’t think of an obvious mechanism, so I’m afraid I can’t help you.

  11. I have read and read and nothing about K-2 and stents. Can I take MK-7K-2   with stents in my heart? Why does it say on the warning label not to take if you are on coumadin or other blood thiners? Thank you .Roy.

    • The warning reflects a misunderstanding of the function of K2 in the body. 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 (reference).

      As to whether it’s safe to take K2 with a stent, I don’t see why it wouldn’t be. In fact, vitamin K2 has been shown to reverse arterial calcification in rats. Nevertheless, you should check with your doctor on this question.

      • Vitamin k2 can be converted to k1 and vis versa, so it can interfere with blood thining medication. Playing with nature while using medications is a dangerous practice.

      • Chris,
        Why are you not explaining about K2 Mk-4, and K2 MK-7?

        You just say K2..
        Big difference, and I think Your Very Misleading.

  12.  
    Hi Chris,
    Do you think if I made homemade yogurt from organic whole milk, and consumed around 4 oz a day  that I would get the necessary vit k2 amounts in my diet? I am kind of confused about the relationship between milk from a grass fed cow (where in the world can you buy milk from a grass fed cow in So. CA?) and the traditional corn fed cow milk (which I think is probably where all of our milk in the city comes from… even organic milk?). I am a lacto/ovo/ fish vegetarian.  I am also genetically predisposed to develop osteoporosis. Thank you for providing this valuable information!!!
     
    Sharon

     
     
     
    Sharon

    • Sharon,

      You can get grass-fed raw milk at Whole Foods in Southern California. That’s what I would recommend. But milk isn’t a sufficiently high source of K2. Raw, grass-fed butter would be higher, which you should also be able to buy from Whole Foods (Organic Pastures is the brand). Fermented cod liver oil with butter oil would also be a good choice. It can be ordered here. Finally, anything else fermented like kefir (which you can also make with the raw milk – do a Google search), raw sauerkraut (buy at Whole Foods or make yourself) or kim chi will be high in K2. You can also supplement with K2 using the MK-4 form. Vitacost.com and other online companies have it.

    • FWIW, cattle in commercial dairies are mainly fed alfalfa and/or grass hay, corn silage (the stalks & leaves are chopped up while the plant is green, and is partially fermented in storage) and other forms of roughage. When grain is fed to cattle it is to promote muscle gain and is mixed in with the other items I mentioned earlier in rations recommended by nutritionists. Feeding them grains exclusively would result in malnourished cattle and the farmer/rancher would go broke in the process since it would be very expensive.

  13. What is the recommended minimum intake of Vitamin K2 per day for and adult male (me) with calcium in the arteries? Doctor has put me on Caduet (a statin I believe) which is giving me several unwanted side effects.
    I have sourced Natto (Nippon Food Supplies) and am planning to replace the Caduet with it.
    Any comments would be greatly appreciated.
    Alan

  14. I think marrow also has lots of K2, so a good marrow bone broth ought to be a good diet addition. I’m still looking for a good reference, though, to support that.

  15. My mother has been k2 for 3 months. She has recently noticed black patches on her face and arms, swelling on one side of face and inside mouth, pain behind her ear leading to her neck. Could this be a side effect of K2? She is on statins, and aspirin.

    • Do not take stations and asparin while on significant doses of k2. K2 is regulator like vitamin the other medication will be affected by it, also vitamin k2 can be converted to vitamin k1 so it is possible to have overly thin blood which would allow local blood vessels in checks to bleed resulting in dark patches like bruising.