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Vitamin K2: The Missing Nutrient

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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:

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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)

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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.

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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.

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437 Comments

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  1. I understand this article is from 2009, but these is some interesting research that has come out recently that may help people.

    http://www.vitamindcouncil.org/blog/dr-cannell-on-vitamin-k2/#

    The link is an article about converting k1 into k2. Consider this quote “…modern humans are deficient in K2 because they do not eat large quantities of vitamin K1 containing foods. If we look at Paleolithic humans, they probably got high amount of vitamin K2 from eating large quantities of kale and spinach-like foods, very high in K1, which then supplied their tissues with all the vitamin K2 they needed.”

    Just some food for thought!

    • It is highly unlikely that the average American gets enough K1 to convert to K2 (MK-4), which, like K1 has a very short half life of 1 – 1 1/2 hours. While there is recycling, K1 can’t be counted on to express K2 activity to a great extent, as K1 has been consistently shown to not improve cardiovascular risk factors the way that K2 (MK-7) does.

      • Michael,
        K2-mk-7 can cause a fast heart beat, and keep you awake at night..It also does not need to be taken everyday..

        K2 MK-4 has a short shelve life in the body. About 3 to 4 hours. It needs to be taken about twice aday, with a little healthy fat.
        Take the calcium to your bones and Not your arteries ..

        Aged hard cheese . Like Gouda cheese has K2 Mk-4..

        We get k1 from Greens…

        • And not just this confusion of vitamin k2, m4 and m7. People are not getting it that vitamin k2 m7 is soy based. Certainly not for people with soy allergies. So take vitamin k2 m4 twice a day. Goes directly to the bones, and clean out your arteries.

          • I mean mk-4 and mk-7. Even if vitamin k2 mk-7 is fermented soy and non-gmo, not all of it is processed or removed.

        • How often should you take k2 and how much supplement. I have high blood pressure and want to come off meds

    • It is reported by other researchers that the Vit k2 from our own gut bacteria is little absorbed since it’s bound to the bacteria bodies that produce it and leaves with our faeces…

  2. Hi Chris, my son is 4 and has been fed a 90% paleo diet all his life. Recently to my shock, we were told he has enamel decay on 6 teeth. Given his low sugar diet, I am at a loss of what to do to prevent further issues. I was looking in Vitamin K2, what do you think? Any thoughts would be appreciated. Thanks.

    • In the second hour of the Robert Scott Bell radio program on October 10, 2014 there is a wonderful informative interview with Dr. Nicholas Gonzales about teeth regeneration. Thank heaven this info is available with podcasting.

      • I live in London, uk. aged 67, female. A severe bone loss in upper (and lower) jaw has ‘suddenly’ been noticed by new dentist. really shocking.
        Regime of cleaning mostly excellent. Diet mostly good: kale, spinach, sprouted shoots, butter, olive oil, coconut cream, all greens, fish, cod-liver oil, no soy, no sugar or wheat (except spelt, gram, rye); fruit and salads. apple cider vinegar fairly often. with teaspoon of raw honey.
        very little meat. Will try liver. I ate part of both placentas (first cooked, then raw, second time!) with both home births, and felt immediately stronger, my milk came in fast.
        No drugs, no vaccines, was brought up on wholely home-grown veg and salads. Local fish, meat or poultry, grass-fed, and this has kept me really healthy.
        Slight palpitations these days, and some joint pains, after bike car-hit-and-run.

        Addiction: breakfast teas, roibosh and herbal infusions from garden (not coffee, much) but indulge in occasional org coco-hemp bits with raw yogurt at night (may be why!) And a case of shock a few months back… New dentist asked “do you smoke?” No. I stopped my one or two rollups a week, ages back. Two kids, four pregnancies.
        Loss of enamel, too.

    • Teeth health is a function of vitamin D, vitamin K, and magnesium via the saliva. It may be that he doesn’t have tooth decay because of sugar, but that he has tooth decay because of insufficient minerals in his diet. He should be taking all of the above, via diet and perhaps supplements to ensure teeth health.

    • I would be investigating for coeliac disease – there is a known correlation between that and tooth enamel defects. Both my daughters have this issue as a result of coeliac disease – and they have a super healthy diet i.e. not much processed sugar at all. I was horrified…

      • see Vit K2.
        ps – i query a link between the ‘coeliac gene’ and K2 since auto immune diseases often associate with abnormal hardening of soft tissue and softening of bone tissue

  3. Very interesting article! Regarding K2 content in meat, how significant is the animal’s diet to the K2 content of the meat? In other words, is ground beef sourced from cattle raised on a conventional feed diet (little to no green grass) high in K2?

    Also, why is ground beef high in it, as opposed to other cuts of beef?

    I’m looking for non-dairy food sources of K2 since my daughter is allergic to dairy products.

    Thank you!

    • Astaire, if a cow stops eating grass for one week, its meat nor milk will not have much vitamin K2 left. Vitamin K2 is fairly short-lived.
      The fermentation process can increase the vitamin K2 content.
      Vitamin K2 is fat soluble and would be higher in fatty meats; I am not sure what ends up in ground beef.
      If your daughter cares to eat natto, about 10 gm of natto has enough vitamin K2 to lasts several days
      Or she could take a supplement derived from soy such as the Twin Lab Dots vitamin D3 + K2 Vitamin
      Take care, PLM

      • Sara,
        Don’t feed your Daughter or any child, person SOY..
        Soy is Gmo, and if its not, it is not food fit for a human.

        Soy is a Hormone to fatten up Cows, Pigs, Chickens etc..
        Its a cheap food..It was really not meant for humans..
        Even in Organic chicken food, the second ingr. is Soy.
        Organic soy is not healthy.

        That said, some of you are going to say, but Asians eat it and there healthy.
        Asian eat Natto, and use it as a dipping sauce..A condiment..

        You might want to ask your Dentist, or a Homeopathic Dr. what is the right way to go for your Daughter.
        SOY is NOT.

        Many people say there allergic to eggs, we are not finding out, its not the Eggs, it’s the Soy the chickens are being Feed..
        Once you find and eat soy free eggs, the allergy to eggs is gone.

        Good Luck, I would be concerned also.

        • Annie,
          Natto is fermented soy, so it doesn’t have the phytoestrogen effect on humans that unfermented soy does. One can’t assume that natto comes from GMO soy, and even if it did the compounds of soy beans are converted into natto kinase (K2) during the fermentation process. Most producers of natto (K2) use a process to isolate the active compound when they produce a K2(menoquinone) supplement. If you want a couple of reputable supplement producers whose manufacturing process has the highest standards, I would be glad to supply the list.

          • Page 62 of Nourishing Traditions says that phytoestrogens are not removed by fermenting or modern processing.

        • Wow, I’ve seldom seen so much misinformation packed into such a shot post.

          First of all, natto is not a “dipping sauce.” Natto is incredibly sticky, and using it for dipping would create a hilarious mess.

          Second, NONE of the soy used in Japan for human consumption is every GMO; it is against the law.

          Third, natto is one of tiniest uses of soy in the Asian diet. The big ones are tofu and tempeh. But those are consumed in rather substantial amounts, and many many different forms.

          Fourth, if you have ever eaten natto, then you would know that it is consumed in such small amounts that the phytoestrogen content would be consider negligible.

          Fifth, although opinions are divided on the topic, many researchers believe it is the phytoestrogens that make soy an inhibitor of breast and prostate cancer.

          People in Japan who eat natto frequently have far lower levels of osteoporosis and cardiovascular disease. It is a traditional food that has been used for about a thousand years and is widely considered to be one of the healthiest foods in Japan.

          But I guess you know better, right?

          • this. many of my same thoughts.
            and yes, the research is heavily split on soy. peruse pubmed and you will find likely *at least* as many articles touting the health benefits of soy isoflavones for men and women alike, as the ones that say they find some harm in soy. soy isoflavones have been found to have preventative properties against prostate cancer, just like it may help protect against breast cancer.
            also phytoestrogens are not the same as progesterone. they just aren’t, no matter how many time people reiterate, hoping that somehow soy turns into birth control pills in the body or whatever nonsense.
            also, some pubmed studies seem to indicate soy may increase testosterone in men, despite many claims saying quite opposing things. lord knows vegan men test for higher testosterone (and sperm counts) than their peers, and many of them utilize soy in their diet… the smart ones utilize less processed soy, the really smart ones eat copious amounts of fermented and whole food, non-gmo, organic soy in numerous forms, including natto, tempeh, miso, tamari, home made soy milk and the things made from that like tofu and live yogurt and cultured cheese, etc.

  4. See this open access article. The abstract follows below
    1 Department of Biomedical Sciences, University of Illinois, Rockford, IL 61107, USA
    2Department of Pathology, University of Illinois at Chicago, Chicago, IL 60612, USA
    Correspondence should be addressed to Munirathinam Gnanasekar; [email protected]
    Received 13 March 2013; Accepted 30 May 2013
    Academic Editor: Richard Pietras
    Copyright © 2013 Abhilash Samykutty et al. This is an open access article distributed under the Creative Commons Attribution
    License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
    cited.
    In recent years, several studies have shown that vitamin k2 (VK2) has anticancer activity in a variety of cancer cells. The antitumor effects of VK2 in prostate cancer are currently not known. In the present study, we sought to characterize the anticancer potential of VK2 in both androgen-dependent and independent prostate cancer cells. Our investigations show that VK2 is able to suppress viability of androgen-dependent and androgen-independent prostate cancer cells viacaspase-3 and -8 dependent apoptosis. We also show that VK2 treatment reduces androgen receptor expression and PSA secretion in androgen-dependent prostate cancer cells. Our results also implicate VK2 as a potential anti-inflammatory agent, as several inflammatory genes are downregulated in prostate cancer cells following treatment with VK2. Additionally, AKT and NF-kB levels in prostate cancer cells are reduced significantly when treated with VK2. These findings correlated with the results of the Boyden chamber and angiogenesis assay, as VK2 treatment reduced cell migration and angiogenesis potential of prostate cancer cells. Finally, in a nude mice model, VK2 administration resulted in significant inhibition of both androgen-dependent and androgen-independent tumor growth. Overall,our results suggest that VK2 may be a potential therapeutic agent in the treatment of prostate cancer.

  5. Dear Chris,

    I heard that warfarin cuases stenosis of the coronaries and Vitamin K may reverse the process and at the same time reverse the coronaries and all blood vessel calcification.
    How correct is this and how long it may tame? Please advise the approximate amounts of K1 or K2, Vitamins A and D, etc.

    Thanks very much.

    • why would you want to take Vit K1 if you are on warfarin? Its purpose is stop abnormal clotting in the human body by acting as a Vit K1 atagonist, so taking additional K1 will only increase the chance of forming a potentially lethal clot.

      Why not change to an alternative to warfarin if you can, though products such as dabigatran cost a lot more.

      • Aspirin is also a blood-thinner and non-toxic… naturally taken from trees. Small doses throughout the year… could help. But diet and exercise and meditation work best. And a loving attitude of gratitude to this wonderful earth… seeing her as our paradise, nurturing and nourishing us despite our worst efforts… without cease. We hold a vision of a whole and healthy and joyfully challenging planet.
        No more cattle pollution… worse than all the cars, factories, aircraft.
        Restored (re-stored) to her rightful balance. We are the only animals to destroy and pollute our nest.
        Nature Rights – be the Voice for Nature’s forests, waters, creatures everywhere.
        And who knows why America began chem-trails?

    • The current recommendations are to take a base level of vitamin K to help stabilize the impact of blood thinners like Warfarin.

      See below, from a discussion by Joanna Becker
      Although it may seem counter-intuitive, increasing evidence has shown that the common anti-green vegetable lecture imparted to all patients starting warfarin may actually be doing more harm than good. Such advice may be setting up patients for a widely variable and difficult to manage INR. Low-dose vitamin K supplementation may actually improvethe stability of anticoagulation therapy.

      What is therapeutic stability and what factors influence it?
      A patient’s ability to achieve a stable INR on anticoagulation with warfarin is essential for protection against thromboembolic and hemorrhagic events. Stability is generally quantified by the standard deviation (SD) of measured INR over a certain period of time. In one study, the median standard deviation of INR in a single clinic population was 0.3 over 6 months. The researchers classified patients as unstable if they had a SD >0.5 and at least 3 changes in warfarin dose over the prior 6 months. Of note, patients with instability attributable to factors such as poor adherence to therapy, other medications, comorbidities, or excess alcohol consumption were excluded.[2] In addition to these controllable factors, stability depends on a number of uncontrollable factors including age and CYP2C9 and VKORC1 polymorphisms. Although genotype can aid in determining anticoagulation initiation doses by being plugged into dose-optimizing algorithms, genotype is not a factor in the ability to maintain stability once it is achieved.[6] On the other hand, vitamin K intake still plays an independent role and thus represents a controllable factor that we can manipulate to improve stability.

      What is the relationship between low dietary vitamin K and INR stability?
      In a 2010 review in the British Journal of Clinical Pharmacology, the authors contend that, “Older recommendations for diets low in vitamin K as appropriate for warfarin-treated patients should now be considered outdated.”[3] Their conclusion is based on research such as the 2004 study by Kurnik and colleagues, which found that vitamin K-depleted patients had significantly greater fluctuation in INR when given vitamin K supplementation when compared with non-depleted patients.[4] In other words, low vitamin K levels cause a patient’s warfarin requirement to vary with even minor changes in vitamin K intake. In 2005, Sconce and colleagues went one step further and demonstrated that patients with low dietary intake of vitamin K were more likely to have unstable control of anticoagulation.[5] These results were then replicated in a 2010 study by Kim and colleagues.[6] When taken together, these studies conclude that patients with low vitamin K intake are more sensitive to minor changes in vitamin K intake and thus more likely to have therapeutic instability.
      Does vitamin K supplementation improve stability?
      Based on the above data, it can be hypothesized that vitamin K supplementation is particularly useful in achieving therapeutic stability in patients with low vitamin K intake. In such patients, daily fluctuations in vitamin K intake lead to significant and proportional changes in INR that can be avoided by oral supplementation.[3] A 2007 study by Sconce and colleagues put this hypothesis to the test in the first randomized, blinded, placebo-controlled trial investigating the effects of vitamin K supplementation in 70 unstable patients over 6 months. When patients with unstable anticoagulation were given 150 mcg of vitamin K supplementation per day, they spent a greater amount of time within target INR range and had decreased daily variability in INR when compared with placebo.[2] These findings were consistent with other literature including a 2005 trial by Reese and colleagues[7] as well as a 2007 study by Rombouts and colleagues[8] using phenprocoumon (a longer-acting vitamin K antagonist) as the anticoagulation agent. Finally, a recent 2010 study by Gebuis and colleagues looked at patients taking phenprocoumon or acenocoumarol and compared the effects of placebo with 100-, 150-, or 200-mcg vitamin K supplementation. Although the supplementation provided improved stability, there was little difference between the doses.[9] Ultimately, low-dose vitamin K supplementation, regardless of dose, was shown to improve therapeutic stability in patients with unstable anticoagulation with warfarin or its derivatives.
      What should we tell our patients? When and in whom should we start supplementation?
      It is clear from the research outlined here that cutting out vitamin K is not the answer for achieving stable anticoagulation. Instead, inform your patients of the vitamin-K rich foods and advise them to maintain a steady dietary pattern. If they have any planned dietary changes or adjustments in multivitamin use, these should be reported. According to the 2008 clinical practice guidelines published in Chest by Ansell and colleagues: “For patients receiving long-term warfarin therapy with a variable INR response not attributable to any of the usual known causes for instability, we suggest a trial of daily low-dose oral vitamin K (100 to 200 mcg), with close monitoring of the INR and warfarin dose adjustment to counter an initial lowering of the INR in response to vitamin K (Grade 2B).”[10]
      In summary, patients no longer have an excuse to avoid leafy green vegetables, missing out on all the other nutrients they harbor as well as vitamin K’s role in slowing vascular calcification[10]. Vitamin K will help rather than hinder the chances of achieving long-term stable anticoagulation. If a patient has a consistent diet and all other causes of instability have been eliminated, try vitamin K supplementation.

  6. I have 3 coronaries heavily blocked, main one close to 90%, the other 2 65% , about to go through stenting on the main one. CT shows sheows calcification index of 4000 against a normal 400. What would you recommend using readily available food or supplements containing K2 or other nutrients. What amount should be taken daily? How long and how good the results may be?

    Thank you.

    • If you have a chance, please read Vitamin K2 and the Calcium Paradox by Kate Rheaume-Bleue. This was recommended by several other posts, and I really liked this book. It took many months (9?), but she reports significant improvement with moving calcium out of the calcified arterial plaque into bones (where it belongs) when BOTH vitamin D3 and vitamin K2 were taken. She recommends the MK7 form derived from natto; a small amount lasts several days. One supplement with MK7 is the TwinLab Dots with D3K2 taken sublingually. It only has 1,000IU D3, so you would ideally add more D3 (probably 5,000 IU daily or enough to get your levels up to 60-80ng/ml of the 25 OHvitaminD). I know that the Weston A Price Foundation eventually determined that the fat soluble Factor X was vitamin K2 (derived from fermented grass-fed dairy fat) in the MK4 form, but the MK4 vitamin K2 takes a much larger dose of 45MG 3x/day rather than about 100MCG (not a typo!) of the MK7 form derived from natto taken daily or every other day. I hope you are also taking magnesium, fish oil and CoQ10.
      Eating natto would be the most helpful since natto contains both nattokinase (which dissolves blood clots) and vitamin K2 (which helps move calcium into bones from arteries and tissues), Keep in mind that vitamin K2 will not work without plenty of vitamin D, another fat soluble vitamin.
      Vitamin K2 also looks good for fighting cancer…

      • Twin labs has changed from MK-7 to MK-4.
        FOLKS…eat the foods!
        Eat cheeses, yogurt, kefir, sauerkraut, offal, bone broth, mollusks, and plenty of greens.

  7. High quality K2 is very expensive but so worth it. A gramme of pure K2 costs around $1000, so a daily dose of 100 mcgs costs 10 cents and that is a wholesale price. Because weighing microgrammes ( a millionth of a gramme) is so difficult the K2 is sold with excipients and in kilo lots with a rating of ppm. We buy 2000ppm in kilo lots for around $2,000 a kilo and so receive 2 grammes when you do the maths. Essential to take with D3 for calcium bone health. It is fat soluble so purists recommend taking it with fat. We add piperine with our MCHC calcium capsules as well as D3 and K2. The piperine aids in the absorption of all three. MoJoe

  8. 99% of soy if GMO, so if it doesn’t say “non-GMO” or something to that extent, believe that it has GMO’s in it.

    Angie (above) –
    Amazing, but Bragg’s Aminos, while they are non-GMO, they are not fermented soy. Chris is right that it’s a processed soy product. Overall, the product is not good for most people.

    • That 99% number is baloney. It isn’t 99% even in the US, and the US has the highest percentage of GMO soy.

      In Japan, all domestically grown soy is non-GMO. They import soybeans from elsewhere (mostly Brazil and Canada), for a variety of purposes, but not for direct human consumption. In addition, most natto is made from a special “natto” breed of soybean.

      Almost all natto for sale in the US is from Japan. But in any case, the amount of natto that you need to eat–a single serving–to get a megadose is extremely small. A serving comes in an individual container that holds 40-50 grams, about an ounce-and-a-half. That’s about two tablespoons of natto.

      Chances are very very low that any natto you buy is GMO.

      And, at two tablespoons, I think that people who are flipping out about phytoestrogens and goiterogens have completely lost their sense of proportion. They’ve been eating natto in Japan for about a thousand years now, and in their culture it is associated with nothing but good health.

    • What if the bacteria in the ferment finds a way to break down glyphosate ? would it not be more beneficial?

  9. Vitamin K2 is not just one thing. There are various types in the “MK” family. MK-4 is the one that WAPF talks about as the “X-factor”. Natto is high in MK-7, not MK-4. This 2014 article goes into great detail…

    Recent trends in the metabolism and cell biology of vitamin K with special reference to vitamin K cycling and MK-4 biosynthesis
    Martin J. Shearer1,* and Paul Newman†

    March 2014 The Journal of Lipid Research,
    http://www.jlr.org/content/55/3/345.long

    • You seem to be claiming that WAPF somehow endorses MK4 and rejects MK7. Just to clear things up, here’s what Chris Masterjohn says in his article “On the Trail of the Elusive X-Factor” at WAPF:

      “Fermented foods such as sauerkraut, cheese, and natto, a soy dish popular in Eastern Japan, contain substantial amounts of vitamin K2. Natto, in fact, contains the highest amount of any food measured; nearly all of it is present as MK-7.26 MK-7 is highly effective: one recent study showed that it increased the percentage of activated osteocalcin in humans three times more powerfully than did vitamin K1.32 There are no studies available, however, comparing the efficacy of MK-7 to that of the MK-4 found in animal products. MK-9, and presumably MK-7, stays in the blood for a longer period of time than does MK-4, but this appears to be because tissues take up MK-4 much more rapidly.30 Whether the rapid uptake of MK-4 or the longer time spent in the blood by bacterial menaquinones have particular benefits or drawbacks is unclear. Future research will have to clarify whether the vitamin K2 synthesized by animal tissues and by bacteria are interchangeable, whether one is superior to the other, or whether each presents its own unique value to our health.

      Supplementing with Vitamin K2

      The best sources of vitamin K2 are fermented foods and grass-fed animal fats. These foods contain a wide array of nutrients that may act synergistically with vitamin K2 in ways we do not yet understand. Price ‘s vitamin-rich butter and butter oil concentrate provided not only vitamin K2 but also vitamin E, vitamin A, vitamin D, conjugated linoleic acid (CLA) and other nutrients. Nevertheless, some people may wish to supplement with vitamin K2 if they do not have access to high-quality food, wish to use a higher dose to treat a health condition, or want extra insurance.

      Two forms of vitamin K2 supplements are commercially available: menaquinone-4 (MK-4), also called menatetrenone, and menaquinone-7 (MK-7). MK-4 is a synthetic product that is believed to be chemically and physiologically identical to the vitamin K2 found in animal fats. This form has been used in most of the animal experiments and in the Japanese osteoporosis studies. Although synthetic, it is effective, and there is no known toxicity. MK-7 is a natural extract of natto, a fermented soy food popular in Eastern Japan. MK-4 is much less expensive than MK-7, but no studies have yet compared the efficacy of these two forms.”

  10. I have been taking 5,000-10,000 D3 per day – my doctor said D was low. I’m interested in taking K2 – how should I take it – I believe Natto is soy – Sloan Kettering told me to stay away from Soy – after having breast cancer. Should I add magnesium supplement? Thank you.

  11. hello everyone. I just want to ask if vitamin k2 helps with blood clotting? because i eat natto every day which provides ample k2 but i read that k1 is required for blood clotting and that the best sources of this vitamin are leafy green vegetables, but i didn’t think these were a good paleo food. I don’t eat leafy greens and i have also read that absorption of vitamin k1 from leafy greens is as low as 10%. So if this is the case i wondered if adequate k2 will help with regards to blood clotting at all? Thanks for any help/thoughts,
    mark

    • nope, K1 is the version of Vit K that is used by the liver to produce the various blood clotting factors. K2 has no impact on blood clotting.

      I’m a long term warfarin “addict” and I have to avoid K1 but can ingest K2.

  12. Hi Chris, I ordered MK4 supplement from Relentless Improvement, each capsule contains 15 mg is this too much mk4 to take daily?

    I read a study that showed mk4 increases testosterone in rats, I wonder if mk4 increases testosterone then your body may produce less naturally, or when you stop taking mk4 similar to how steroids effect testosterone production?

    Thanks

  13. Hi Chris,
    Thanks for very interesting article, dad had three heart bypass twelve years ago, stopped taking statins couple of months ago and I am interested in the possible reversing of calcification in arteries. Live in Australia and would like to know if by eating Brie an Gouda cheese would provide enough vit k2 and how much cheese should be taken daily, also does blue cheese also contain vit K2? Thanx

  14. Chriss,

    I know that good sources of K2 is hard cheese and especially GUDA cheese, because of the kind of the microorganisms that make it. But I read that yogurt hasn’t any.

    I am not convinced that KEFIR has K2 and you don’t give us any proof. Is there any web page showing that?
    Thanks!

  15. Do you have any advice on K2 for paediatric dosing? I’m looking to supplement my 3 yr old with D3 but I’m reluctant without also ensuring that she has a K2 supplement and magnesium. I’m finding it very difficult to find information on a sensible K2 dosage – or whether it’s best to do these things off age or weight. Based on weight – 30lbs – I’m considering up to 1000iu D3 and 100mg magnesium citrate, I’m reluctant to proceed without the vitamin K2, but she could really use the boost to her immune system. Any help gratefully received!

  16. While obviously the best source of vitamin K2 (Mk-4 and Mk-7) is from whole foods. There is a supplement I take that contains both types in it called the Daily Multi Nutrient. I think it’s a good option, especially considering some of the preliminary research behind supplemental K2.