Vitamin K2: What It Does, Its Benefits, & Where to Find It | Chris Kresser
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Vitamin K2: The Missing Nutrient

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

This bowl of natto is a good source of vitamin K2.
Natto, a fermented soy dish, is a good source of vitamin K2.

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:

  • Preventing cardiovascular disease
  • Ensuring healthy skin
  • Forming strong bones and improving bone health
  • Promoting brain function
  • Supporting growth and development
  • Helping to prevent cancer
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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)

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)

Vitamin K2 and other fat-soluble vitamins play an important role in our health. Figuring out the best sources of these and other nutrients isn’t always a straightforward process, especially if you’re just getting started with learning about nutrition and improving your health. Even if you have knowledge of good sources, it may be difficult to add new food into your diet. Natto, for example, is a great source of K2, but some people really dislike its taste and do better with other K2 sources.

Health coaches are a great resource for helping you make changes to your diet. They not only have a broad knowledge of diet and nutrition, but they also know how to help you navigate dietary changes to make them successful and sustainable.

If supporting people with successful diet changes and helping them improve their health sounds like the career for you, consider becoming a health coach. To learn more, check out the ADAPT Health Coach Training Program.

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.

I’d like to hear from you. Have you heard about the potential health benefits of K2? Do you eat a diet rich in this vitamin, or are you concerned about a nutrient deficiency? Tell me in the comments below.

437 Comments

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    • Mmmm, not sure that’s so, Christine. I just went to the database (thanks for the url, BTW). It seems to only include measures for MK-4 rather than MK-7; the latter form, I think, is more likely to be found in food. More important, it looks as if they indicate the value of 0.0 when a nutrient is absent. I just checked items in the dairy category (looking for certain cheeses), and what’s overwhelmingly listed is an n-dash, meaning not measured. My guess is that there is currently neither the money/staff nor the incentive for this part of the USDA to test for for both forms of K2 among the vast array of foods on their list. Too bad…

  1. 2 pops ups. While I was trying to read and concentrate I had to stop. I had to find where to eliminate the first pop up. Then the second one. So this actually interfered with my gaining knowledge and taking in what the post was about. And it added frustration which triggers cortisol which is bad for you. It also seems to be counter to all the stuff you write about being healthy and stress free. I’d like you to write an article about pop ups and how you justify using them on here. It’s also insulting to everyone’s intelligence since we could read about those things from a sidebar link if we choose to.

  2. Hi Chris, I just have a thought on vitamin k1 if I may? I read that the best source of this fat soluble vitamin is low fat leafy greens! And that you should also consume those leafy greens with fat! I am struggling to believe we evolved eating leafy greens for our k1 so I was wondering if we could not get k1 from animals who ate grass? They would eat the k1 in the grass, then we would eat them. I know grass fed meats are a source of omega 3 fatty acids, so could k1 also be found in grass eating animals? Would make a lot more sense to me from an evolutional point of view too, as I am sure leafy greens should also be cooked first before eating for maximum nutrition???
    Just a thought,
    Best,
    Mark

    • Mark, when you struggle to come up with a just-so story about how humans could obtain a vitamin, it means either (1) you are missing something, or (2) it’s not really needed all that much, but it being hyped by pill sellers.

      In the case of K1 and B12, both of these are in our poop, and as monkeys we used to eat our poop. It’s also possible that having lost 1200 species of gut bacteria, we are not able to absorb it from our intestines like we used to.

      Also, with omega-3, you will notice a staggering lack of real human in-vivo science demonstrating deficiency, or backing up omega-6 ratio inflammation hypotheses. It’s all hot air, to sell pills. When you search through the USDA food database for omega-3 in mammal flesh, you come up with nearly bupkus. Somehow all these mammals can survive and grow, without much omega-3. You know this, but it still doesn’t cross your mind that something is fishy.

      • Yes, like large land animals that are herbivores are super muscular and have strong healthy bones. They are obviously not eating salmon or any fish oils. I had already figured this out but then sometimes all the hype starts creeping in and I think I need it again. But if I do I’d rather eat fresh fish to get it, not a 1 year old capsule or whatever it is. But DO I need it is a very good question. Just because something isn’t bad for you, say eating salmon once in awhile, doesn’t mean you need it. Are there any mammals that don’t eat some plants? Even cats eat grasses. Why wouldn’t we have eaten fruits and tender greens when available? Same with cooking, just because it releases stuff in some foods doesn’t mean that we needed to do that in the first place. I’m sure we did eat some foods semi-cooked by the sun, in varying degrees of being broken down, so to me it would be natural to have some “cooked” foods as well as fresh.

      • Chris Walker,
        What is your source for the statement about losing 1200 species of gut bacteria? Is that from a study or how would they prove or know that? Just so you know my “tone” is totally passive – I’d really like to understand this.

  3. i started using K2 to absorb minerals into the bones. the benifits are great. for my restless leg sindrom i can lay in bed all night without my legs jumping.

  4. I understand the dairy has k2 if the cow was eating grass, not grain. If that is correct then would it be right to assume that all the animal parts you mention would have the K2 if the animal was grass fed. You are implying that all the animal parts you mention have K2, regardless of the grass-fed factor. Please respond. thank you

    • I believe it’s the fermentation process of the dairy i.e. Cheese and Kefir that produces the K2, regardless of whether the cows were grass or grain fed.

  5. Can the Parkinson’s be reversed by coming off statins ? My dad was taking statins for 16 years and he developed Parkinson’s in 2010 he has never had any shakes and yet was diagnosed with Parkinson’s in 2010.
    He is now also being treated for dementia and is now in a care home , he has been taken off statins 29 December 2016 and already his left side of this body has started to work again , before he couldn’t use his leg or his arm , now he can . He is a very very ill man and hallucinating because of the mementine he is being given along with Parkinson’s meds .I’m probably wishing for too much to believe these Parkinson’s and dementia symptoms can be reversed and that statins are the blame of his diagnosis .

    • My advice is to never start more than one drug at a time, so one can see how the body reacts. You seem to already know what the problem is. You can say, No! to a drug. Do your research and don’t be afraid to talk to the pharmacist as many times as you need. Unfortunately, we live in a culture where drugs are pushed, and my experience has been that doctors do not remove a drug unless replaced by another, but just keep adding other drugs that usually exasperate the problem. You, the person speaking for the patient, or if the patient is able themselves must stand up for their health and well being, even if it means you take flack. You have a say. Do it nicely though. You can say no, if need be. No one should have to live with hallucinations, etc. Living an enjoyable life as much as possible should be balanced with medical care (which includes medications). Medications are not the end authority nor are doctors like too many people think. Research and find a balance. I am not saying totally go away from doctors – find a good one, but a highly qualified natropath can really help. Doctors do not cure, but medicate symptoms. Natropaths know how to cure many diseases – for good! Quality of life should be the goal – always!

    • being in a home he will be eating all the foods that are poison to the body. look at the ingredents on what you eat and you will find soy in everything, that alone will give you nothing but problems. learn more go to Tony Panteresceos web pages his site is called To your health with Tony P you can learn how to protect your self from the poisons in the food industery.

    • In the excellent book, The Alzheimer’s Antidote, it is recommended to eat a low carb diet to prevent and treat dementia. Some studies indicate the same for Parkinson’s disease, as well. Best wishes to you and your dad.

  6. Hi
    I have a problem with gouty arthritis so I am interested to learn that K2 helps fight gout or any arthritis.

    Your article is most interesting, even so I am puzzelled by the list of recommended foods high in K2 Natto, Hard cheese, Soft cheese, Egg yolk, Butter, Chicken, liver, Salami, Chicken breast, Ground beef to combat arthritis as most of them apart from eggs and chicken breast are high in purines, which leads to a high production of uric acid and therefore the kidney spilling the needle like uric acid crystals into the blood stream and therefore getting into big toe or even other joints.

    Would you kindly explain?

    Regards
    Robert

  7. I’m thinking it’s MK-9 which causes the pronounced results of the Rotterdam study. (If we assume it’s an MK at all.)

    https://www.ncbi.nlm.nih.gov/pubmed/15514282?dopt=Abstract
    https://www.ncbi.nlm.nih.gov/pubmed/17699024

    The reason is that, we only get therapeutic results from very high levels of MK4 (45000mcg) and MK7 (1000mcg), which are absent in natural foods consumed by Rotterdam people.

    MK-9 is consistently found in cheeses at higher levels than 4 and 7. Norwegain Jarlsberg is king (64ug/100g), but half that level is found in other hard cheeses. I can’t find any reliable info about MK-7 or MK-9, apart from the above study. It appears to be recycled internet rumours.

    • Chris,

      There’s no clear evidence for these dose conclusions. 45 mg/d used in Japanese osteoporosis trials is using MK-4 as a drug, to achieve a pharmacological effect of a supraphysiological dose that is fundamentally different from its nutritional effects.

      While there are no clear RCTs showing therapeutic effects of much smaller doses, that is mostly because they haven’t been done.

      Chris

    • Hi, I am sorry, don’t know whether it is ok to ask it here or not, since I am on warfarin and having stomach problem like bloating and breathless sometimes and want to give a try for milk Kefir as I have read very much about this as it is very much useful for stomach, I tried a lot to know the nutrition fact of Kefir but did’t get the actual amount of Vita. K found in Kefir since I need to avoid Vita. K to maintain my INR. Can someone tell me the same, also as K1 and K2 are different so can I have Kefir as it contains Vita. K2.
      Looking forward for your kind help in this regard.
      Thank You!!

    • Good focus on various types of prenylated quinones with increasing fat solubility often lumped together as K2 like mk4, mk7 and mk9, closely related to mk10 or Q10 with 10 linked isoprenyl units. Wikipedia under Vitamin K shows a large list of K foods with decreasing levels of various types, mk4 predominant. Question: which is healthier, mk4 or mk7 and at what daily dose?

  8. Hi there,

    I have recently started supplementig K2 (from natto) and I get menstrual-like cramps (even in the middle of a cycle) since the first day of doing so. I don’t get any cramps if I skip taking vit K2. Shall I stop taking the supplemnt?

    • Why don’t you answer your own question?!
      Some questions are wrong to question,
      By the way, if you’re getting your period, you don’t have to tell the whole world about your cramps, it’s a little bit pain and it goes away after few days, big deal
      Peace to you and the world

    • I’m no doctor but I theorize this could be caused by the Natto eating away the plaque and dead tissue in your body. There is so much of it that removing it is taxing your system – especially your liver and kidneys. Serrapeptase and similar enzymes have the same effect on your body, and must be taken in moderation, especially until your body has less of this plaque and dead tissue built up. I’m not saying to stop taking K2, but you should take less of it for now, and be sure to stop eating food that creates this plaque buildup. Sorry; I know how tasty fried food is, but if I can give it up so can you.

      • Correction: What I mean is you should slow down with the Natto consumption. Try taking K2 in a pill form instead.

    • Not sure if u are eating natto or just taking extracted mk-7. If eating, perhaps it’s causing cramps because it’s re-balancing gut flora (die off)?

    • I am not sure if this is relevant but soy has estrogen like compounds and you may be having increased menstrual bleeding due to natto being a soy product.
      I am very sensitive to soy. If I consumed soy products every day it would cause me to have my period every other week.

      • Natto is fermented and is not supposed to cause any estrogen issues or phytic acid problems because of the fermentation.

    • The cramps may be from the plant-based estrogen in the soy, not the K2. Perhaps you should try another source for your K2, such as cheese or eggs or sauerkraut.

      • HI Lisa,
        Are you from earth clinic also?
        I am trying to find an amount of K2 contained in Milk Kefir or water kefir
        Do you have any ideas or direction to this ?
        Thanks
        Shane

  9. Cancer this cancer that. All based on stats that did not consider the known causes and pathways. Where are these? Open The Cure and Prevention of All Cancers, 2007. 600 pages, Clark H R PhD ND.. for 99% prevention and much cure.

    In the UK the 1939 Cancer Act prohibits the publication of any cancer cure. In the US the Med Js refuse to accept any cancer cure. I.e Dr. R Good.. the natural pancreatic cancer cure. Dr Good was leader in immunology with the world’s 1st bone marrow transplant and 2000 published papers!

    Nor are you told how to stop overburdening and then boosting your immunes system.. whose functions is to prevent cancer with your CD4, CD8 and CD14 leukocytes, your killer white blood cells. See the Immune Guide part of a set of 11.. in the tthairsolutions dot com site.

    • Hulda Clark is a partially batshit insane scammer, she claims her son invented Rife Tech, and makes tonnes of other totally BS claims, such as all cancers come from snails/slugs, cancer is CAUSED through chemical and electrical harm, period, NOT SLUGS. Even Dr. Rifes works are vastly superior to any of her BS…learn the truth about disease, and do not take it from new agey nutbars with their completely half truth insanities.

  10. Hi there I have a question about this. Will the vitamin K2 amount be dependent upon whether or not the butter is raw, even if it is from grass fed cows?

    • No, it’s the fermentation process that produces the K2, so it doesn’t matter if the butter is raw, or from grass fed cows.

        • Where does the butter flavor come from if it’s not fermented. I’ve always thought that butter flavor comes through the fermentation of lactococcus lactis subsp. diacetylactis. I’m a food microbiologist, and that’s my understanding. Butter flavor comes from diacetyl, and it can be added as an artificial flavor (and would need to be on the label), or it comes from the organism I mentioned.

      • If you read the post, levels of K2 in butter are highest in grass-fed butter IF there is great depth of topsoil. So, the soil quality counts as well, which is not surprising.

  11. i thought this section from a review on vitamin K was interesting as it appears to contradict what is mentioned above.
    Chris what do you make of this please?

    The health benefits of vitamin K
    James J DiNicolantonio1, Jaikrit Bhutani2 and James H O’Keefe1

    Vitamin K1 (5 mg daily) given to 440 postmenopausal women with osteopenia for 2 years in a randomised, placebo-controlled, double-blind trial caused a greater than 50% reduction in clinical fractures (9 vs 20, p=0.04) versus placebo, despite the fact that there was no improvement in bone mineral density.18 Moreover, there was a 75% reduction in cancer incidence with vitamin K1 (3 vs 12, p=0.02). The benefit of vitamin K on bone is thought to be unrelated to increasing BMD but rather increasing bone strength.19 A recent meta-analysis has shown that vitamin K2 (45 mg/day) significantly reduces hip (77% reduction), vertebral (60% reduction) and all non-vertebral fractures (81% reduction).20 Whether the results of vitamin K2 at a dose of 45 mg can be translated to over the counter doses of vitamin K1 (such as 1–5 mg) is still a matter of debate, but vitamin K1 on its own has already been shown to reduce fractures and cancer in a clinical trial, although more data are needed to confirm these benefits.

  12. My father takes Salospir as an anticoagulant, after bypass surgery.
    Can he take vitamin K2 supplements?
    Thanks.

    • Yes actually! I was so happy to learn that at least one kind of spirulina contains bioavailable k2. I use Nutrex spirulina and you can find research on their site supporting the finding of k2 in their spirulina.

      Other brands of spirulina may contain k2 as well. I imagine it probably has to do with the water it is grown in.

      I ran into a major k1/k2 deficiency when trying to get my vitamin d levels up. I’ve been taking about two tablespoons of spirulina a day and I’ve made huge improvements. I can actually feel the difference. Less brain fog, more present, and much better sleep and dreams.

  13. I’ve searched through some of the comments on this article, and didn’t see my questions addressed… Chris, can you or one of your colleagues comment on the potential risks associated with Vitamin K2 supplementation for those on oral anticoagulant therapy? As a registered nurse and health coach, I’m curious, as some of my clients fall into this category. Some of the research I’m reading is that supplementing with this can decrease INR values (i.e. increase clotting tendency). Thanks!

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