Vitamin K in Leafy Greens

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What are the best sources of vitamin K?

I have read in a magazine that there are several types of vitamin K. According to the article, Vitamin K1 is found in vegetables. Vitamin K2 mk7 is found in meat, fish and eggs. The article also said that Vitamin K1 is stored in the liver for only one hour, time not enough to perform all its tasks. On the contrary, vitamin k2 mk7 would stay in the liver for the whole day. So my question is: should vegetarians take supplements of vitamin k2 mk7 (created from natto)?

vjimener / Originally posted below Better than green tea?


Not sure what magazine you were reading, but the scientific consensus is that either one (phylloquinone or menaquinone, formerly K1 and K2) is fine for maintaining human vitamin K status. The recommended intake is about 100 mcg. A half cup of kale? >500. No need for natto; just eat your greens.

In fact dark green leafies are so packed with vitamin K that if you’re on the drug coumadin (warfarin), a drug that works by poisoning vitamin K metabolism, you have to closely work with your physician to titrate the dose to your greens intake so as to not undermine the drug’s effectiveness!

Learn more about the wonders of greens in my greens videos (like Eating Green to Prevent Cancer) and kale in particular in videos such as Smoking Versus Kale Juice and Kale and the Immune System.

Image credit: ilovemypit / Flickr


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

103 responses to “What are the best sources of vitamin K?

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  1. Isn’t vitamin K1 distinct from K2. K1 plays an important role in coagulation. K2 plays a role in directing where calcium gets stored. Too much calcium in the blood can cause calcification, K2 helps direct the calcium to the bones. If that is true, don’t we need to satisfy our requirements for K2 specifically? Sounds like we would need to be getting some natto after all.

    1. No need to eat Natto if you don’t want (I’ve tried it and it’s yuck). Just have lots of greens, e.g. kale. Vitamin K1 gets converted into vitamin K2 in your body. The conversion occurs with 15% efficiency, but because green are so packed with vitamin K1, you’ll end up getting enough.

      1. No, humans don’t have that capacity. Weston Price did a 9 yr study in the 1930’s over the world, and during a time where vitamins were first being discovered, he found factor X was important for bones and tooth development, later we named it k2, the dairy animals convert k1 from live green pasture or algae in the ocean, to k2 in their livers and milk or eggs. But most dairy animals are no longer on live greens. Hay is not the same and most dairy cattle are in barns eating silage not even allowed out in the sun( that’s how they manage to make d deficient milk. ) And now they are making k2 deficient milk and A deficient milk, also magnesium used to be found in milk , now it is not regarded as a good source, they don’t replace minerals like magnesium much in farm soils, so it won’t be in the food. As long as they depend on NPK for fertilizing, that’s what we are stuck with.

        As for the doc, out if 129 medical schools only 29 have any sort of nutritional training at all.

      2. Vitamin K2 MK7 has a very different function than K1. K1 does not convert to K2MK7. If you are deficient in K1, it will convert some of the K2MK7 into K1 but not the reverse. K2MK7 activates osteocalcin in the bone and directs calcium absorbed in the intestine to be stored in the bone. K2MK7 also activates matrix GLA protein in your cardiovascular system which not only inhibits vascular calcification but removes calcium from your cardiovascular system. If your diet is deficient in K2MK7 calcium will be stored in the soft tissues of the body ( gums, arteries, kidneys, skin) and osteocalcin will not be activated resulted in osteoporosis. If you have issues with tartar buildup on your teeth, it is a sure sign that you are K2MK7 deficient and you can be sure that calcium is also being deposited in your cardiovascular system. And the best predictor of myocardial infarction (heart attack) is not your cholesterol level, its your calcium score (according to AHA). Vegans can get K2MK7 by eating Natto or by supplement. I wish Dr. Greger would address this issue in a video. You can learn more about K2MK7 at

        1. Truthseeker30: I don’t consider Mercola to be a very trustworthy source of information.

          Brenda Davis and Vesanto Melina wrote a reference book called Becoming Vegan. They did extensive research into individual nutrients, including vitamin K. On page 119 of the Express Edition, the book says: “If you follow popular health gurus on the Internet, you may wonder if you need supplemental vitamin K2, since little of this form is present in a vegan diet. At this time, there is no scientific evidence to suggest that vegans need to worry about supplementing with Vitamin K2.”
          That’s a trustworthy source. They make note that leafy green veggies are vitamin K superstars. And it is easy to get enough Vitamin K on a whole plant food diet. That seems to be all we need to worry about. There is no (credible) scientific evidence, at least by 2013 that says otherwise.
          On page 119 is the text, “…intestinal bacteria synthesize forms of this vitamin known collectively as vitamin K2…” I interpret that to mean: It looks like our bodies make K2, as least in those people who have healthy guts. Perhaps rather than worrying about consuming K2, people should strive for the goal of consuming gut health promoting foods such as intact grains.
          I found backup for my understanding of K2 from an article written by another well respected expert, Jack Norris RD: “Menaquin one (K2) is produced by a number of different bacteria species that typically live in the digestive tract of humans, and can be absorbed in the distal part of the small intestine. Unless someone has had significant antibiotic therapy, they should have plenty of such bacteria providing them with menaquinone.” Anyone concerned about vitamin K in any form, may want to check out this article: (Thank you Darchite for bringing this to my attention!)
          For anyone that missed it, Tom Goff some time ago on another post with a page link on some more technical information about K2. (Thank you Tom!). If you want the more technical details, check out this interesting page:

          1. My comment on Vitamin K2 MK7 was based on a much more extensive review than just the article from Dr. Mercola’s site. I chose his article because I felt it was an accurate summary of the more extensive and much more technical articles I had reviewed. There is an extensive literature based on academic research on the value of Vitamin K2 Mk7 to protect against cardiovascular disease and osteoporosis. Unfortunately, for vegetarians, this vitamin is not available from eating green leafy vegetables.
            Some examples are listed below.

            The Rotterdam study in 2004 which showed that supplementation with vitamin k2MK7 is associated with reduced risk of coronary heart disease. See abstract of study at this link plus additional research references.

            There have been many more confirming studies since 2004.

            Also see Dr Whitcomb’s (MD) presentation on Vitamin K2 Mk7

          2. I just read the article you referenced at the Linus Pauling Institute and they confirmed what I had previously stated and list several studies that show Vitamin k2 Mk7 has a protective effect for osteoporosis and cardiovascular disease.

            Below are some of the studies that they refererence:

            52. Ikeda Y, Iki M, Morita A, et al. Intake of fermented soybeans, natto, is associated with reduced bone loss in postmenopausal women: Japanese Population-Based Osteoporosis (JPOS) Study. J Nutr. 2006;136(5):1323-1328. (PubMed)

            54. Kaneki M, Hodges SJ, Hosoi T, et al. Japanese fermented soybean food as the major determinant of the large geographic difference in circulating levels of vitamin K2: possible implications for hip-fracture risk. Nutrition. 2001;17(4):315-321. (PubMed)

            65. Knapen MH, Schurgers LJ, Vermeer C. Vitamin K2 supplementation improves hip bone geometry and bone strength indices in postmenopausal women. Osteoporos Int. 2007;18(7):963-972. (PubMed)

            68. Knapen MH, Drummen NE, Smit E, Vermeer C, Theuwissen E. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporos Int. 2013;24(9):2499-2507. (PubMed)

            78. Gast GC, de Roos NM, Sluijs I, et al. A high menaquinone intake reduces the incidence of coronary heart disease. Nutr Metab Cardiovasc Dis. 2009;19(7):504-510. (PubMed)

            79. Geleijnse JM, Vermeer C, Grobbee DE, et al. Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study. J Nutr. 2004;134(11):3100-3105. (PubMed)

            85. Beulens JW, Bots ML, Atsma F, et al. High dietary menaquinone intake is associated with reduced coronary calcification. Atherosclerosis. 2009;203(2):489-493. (PubMed)

            87. Schurgers LJ, Uitto J, Reutelingsperger CP. Vitamin K-dependent carboxylation of matrix Gla-protein: a crucial switch to control ectopic mineralization. Trends Mol Med. 2013;19(4):217-226. (PubMed)

            88. Cassidy-Bushrow AE, Bielak LF, Levin AM, et al. Matrix gla protein gene polymorphism is associated with increased coronary artery calcification progression. Arterioscler Thromb Vasc Biol. 2013;33(3):645-651. (PubMed)

            91. van den Heuvel EG, van Schoor NM, Lips P, et al. Circulating uncarboxylated matrix Gla protein, a marker of vitamin K status, as a risk factor of cardiovascular disease. Maturitas. 2014;77(2):137-141. (PubMed)

        2. Mercola info needs a filter. A lot of pseudo-sciences there. But hey it makes a great case fo buy lots of supplements. Making the guy rich.

        3. My husband and I had wanted to do a calcium score test for a few years. He has had elevated cholesterol for a number of years (in the 300’s at times). Mine usually was 200-218. Finally, we both had a calcium score test done at hospital in a nearby city on Sept 9, 2016. Literally, the next morning on Sept 10, 2016 I suffered a mild heart attack. My husband and I were very interested to see what the results of the calcium score would be once received. Two weeks later, I received the results in the mail saying “The coronary calcium scan does not detect any calcification of the coronary arteries. The total coronary calcium score is zero. This result implies a very low risk of cardiovascular event within the next 10 years.” Interesting, because I had two blockages (soft plaque) in the same artery. Due to the length of each of the blockages, I had a stent placed at the beginning and end of each of the blockages so 4 stents total. And then I read the results of the calcium score that said “very low risk of CVD within the next 10 years”. The problem with calcium score tests is that they only detect hardened plaque. They do not detect the soft plaque and the soft plaque is what will kill you because it can break loose and travel along causing either a stroke or heart attack. Please don’t think if you get a calcium score test done and the results are similar to mine that you are in the clear. Sure wish there was a test that can clearly see soft plaque buildup without doing a heart catheterization.

          1. Linus Pauling received a patent for a protocol that successfully removes and inhibits soft plague build up in the cardiovascular system. One of the primary culprits of plague is Lipid (a). L-lysine inhibits the build up of plague in the cardiovascular system and can actually reverse it. The protocol is 2 grams of Vitamin C and 2 grams of L-lysine both taken 3 times per day. The vitamin C stimulates collagen growth which helps protect the cardiovascular system and L-lysine reverses lipid (a) buildup in the cardiovascular system. See more on this at

        4. I agree I wish he would do a video on it . Even though natto doesn’t taste good you can disguise the taste with a bunch of different flavors an textures to get it into your diet. You probably only need a one cup a week. Dr. Mercola has a great article on natto an all of the Postive health benefits it has. Come on dr. Gregor please make a video on this

        5. I agree. That’s been what I’ve found in my research. Dr Greger seems to think everything leads back to eating a little kale. Simply not true.

    2. The Rotterdam study’s results published in the Journal of Nutrition in 2004 by J M Geleijnse et al present some very impressive results such as a 57% RR reduction for cvdi and 52% reduction for death from cvd over the 7-10 yrs of the study for the mid and upper quartiles based on K2

  2. I like natto bec it is fermented and the vitamin k2 from natto is a nice bonus. I have been able to find low salt natto bec I don’t like any added salt. I have already decided to get rid of miso since I cannot find low salt miso.

  3. I was reading K2 and Calcium Paradox and it indicates the only non-animal source of K2 is natto (which I don’t like). It also says K2 is not the same vitamin as K1.. ie. K2 prevents atherosclerosis, diabetes 2, cancer, and osteoporosis, etc, whereas K1 only helps with blood clotting. I tried researching on internet if this is true or quackery.. I don’t believe everything I read.. but so far have not found information on sites I would consider trustworthy.

    1. They are different, but you don’t need to eat K2. Eating enough K1 will result in the K1 being converted to K2. Bottom line is get enough greens. Drink green smoothies, e.g. blend some kale with banana and chia seeds.

      1. dorange: I have some information about K2 which I have shared in the past with others. Maybe this will help you too:

        Brenda Davis and Vesanto Melina wrote a reference book called Becoming Vegan. They did extensive research into individual nutrients, including vitamin K. On page 119 of the Express Edition, the book says: “If you follow popular health gurus on the Internet, you may wonder if you need supplemental vitamin K2, since little of this form is present in a vegan diet. At this time, there is no scientific evidence to suggest that vegans need to worry about supplementing with Vitamin K2.”
        That’s a trustworthy source. They make note that leafy green veggies are vitamin K superstars. And it is easy to get enough Vitamin K on a whole plant food diet. That seems to be all we need to worry about. There is no (credible) scientific evidence, at least by 2013 that says otherwise.
        On page 119 is the text, “…intestinal bacteria synthesize forms of this vitamin known collectively as vitamin K2…” I interpret that to mean: It looks like our bodies make K2, as least in those people who have healthy guts. Perhaps rather than worrying about consuming K2, people should strive for the goal of consuming gut health promoting foods such as intact grains.
        I found backup for my understanding of K2 from an article written by another well respected expert, Jack Norris RD: “Menaquin one (K2) is produced by a number of different bacteria species that typically live in the digestive tract of humans, and can be absorbed in the distal part of the small intestine. Unless someone has had significant antibiotic therapy, they should have plenty of such bacteria providing them with menaquinone.” Anyone concerned about vitamin K in any form, may want to check out this article: (Thank you Darchite for bringing this to my attention!)
        For anyone that missed it, Tom Goff replied to George in another post with a page link on some more technical information about K2. (Thank you Tom!). If you want the more technical details, check out this interesting page:

        1. Thanks, Thea, a lot to read! My concern is about the effects K1 and K2 seem to have on the body. I was prescribed vitamin K2 + D3 because of osteoporosis, and a related bone fracture. However, since I have other conditions that make me prone to clots, I am always cautious about taking K2 – a kind of catch 22, since I take omega-3 supplements as anti-inflammatory and blood thinner. Thanks agais, great stuff!

          1. dorange: Ah, that’s a more complicated question than I realized. I forwarded your post onto our medical moderators. We don’t have enough volunteers to answer every question, but at least your question is in the pile.

  4. I think the research that Michael cited is out of date (published in 2009). I would suggest people read the review article “The role of menaquinones (vitamin K2) in human health” published in the Cambridge Journal of Nutrition in 2013. It states that Vitamin K2 has an important and distinct role in bone health. It also provides evidence that absorption of K2 produced by intestinal bacteria is very inefficient (because the K2 producing bacteria are located in the colon whereas K2 absorption happens in the small intestine). Therefore it recommends that everyone take a form of K2 every day, either from natto, animal products or supplements. (I’ve been taking a vegan K2 supplement sold by;jsessionid=8485084EC3B24DE5762B43FB087A1FBF.journals?fromPage=online&aid=8894242

    1. I am really surprised to see someone claim that the bacteria in the colon are different species than what you find in the intestines. Doesn’t pass the smell test.

  5. I strongly believe that vegan it is only possible to take profit from a vegan diet , rich in many useful nutrients, if we don’t turn a blind eye towards the downsides of not eating meat. Such as Vit D, Vit B12 , possibly Vitamine K(2) and who knows are there more …

    Vegans seem to have so much benefits , yet , no higher life expectancy proves that we are still missing some pieces of the puzzle, wood you agree to that ?
    So I am looking beyond what is served to me today.
    Maybe I found something here:

    I (53) have been taking Natto for a few weeks now and , waaw
    Before , being a vegan for over a year now, I can solve some of my healthissues but found it hard to make my bloodpressure move just a little bit…..

    Eating Natto , my bloodpressure 140/90 (150/100without medication ) just dropped to 110/80 (95/60 by moments). Waaw , this is not food , just a table spoon every day does more then medication. I am impressed. Yet it is not a structural solution to my high blood pressure.When I stop eating for a few days my BP goes up again.

    As for the longterm effects of other components in Natto , they remain to be seen, I am hopeful however to reduce some calcification in my arteries by eating Natto. More and more research from the past 10 years starts to indicate that it might be possible.

    K1(vegetables) and K2(from Natto) may have the same value in terms of directing calcium form our arteries towards our bones, K2 stays in our blood for days whereas K1 seems to be eliminated after few hours , hence we should eat tonnes of green leaves to keep up a certain level of K1 in our blood, while a tablespoon of Natto every day can do the trick 10 times better.

    (btw, I am not producer or selling Natto:) )

    1. Dr. William Li says one can get high amounts of K2 from Natto but most westerners hate it. He says you can get large amounts of K2 from Gouda, Ementhal cheese,l Jarlsberg and Edam cheese. He says it helps prevent cancer, prevents heart disease, by keeping arteries flexible, helps deposit Calcium in bones instead of blood vessels. I am hoping that Dr. Gregor might comment on this.

    2. Same story here, impressive research and results.

      I throw a chuck of frozen natto through kale/red cabbage/spinach vegetable shakes,
      as long as there are some peanuts in there and or strawberries it gets to be quite tasty to me.
      These two ingredients really transform the blend from an atrocity into something much much better ^^.

    3. I actually like natto now. Not the first time I ate it, I had to choke it down. The second time it was just meh. Now I like it. I’ve found that however I eat it, it is best with a lot of spicy mustard (Coleman’s is a good brand), I used to eat it with rice, not I make a soup out of it with miso and mustard and sometimes ginger. I know I feel great when I eat it regularly. Natto contains spermidine and another of Dr. Greger’s videos cited health issues associated with spermidine; I had previously thought that spermidine was good for health since it promotes autophagy – taking out the cellular trash. So I am wondering if natto really is overall good for health or not. Many Japanese eat it for breakfast (and I understand many eat it because it is thought to be healthful, not because they like it) and they have good life expectancy, but this is just one food in a diet that is quite different overall from Western diets.

      I wish Dr. Greger would do a ‘natto – good or bad’ video.

    4. I have had a similar experience regarding blood pressure, I was also bruising easily.
      I also swear by Natto.
      I have not read the book Dr Greger recommends but I have read journal articles which support what you and I describe.
      I am I little surprised by how catergorical Dr Greger is on this topic, using a traffic light system it would seem to warant an amber more research needed compared to Dr’s red not needed. I can’t even find how much the forms of K2 kimchi can contain (sauerkraut does apparently contain forms of K2), this for a group of molecules the research shows have effects and that at least some people don’t synthesise regularly.
      Researchers studying the gut microbiome say fermented food is good but they don’t know why.
      Blue zone residents also consume fermented food.
      So we have the longest lived people consuming something Dr says is not needed.
      And the majority concuming far more than they need.
      All my evidence is circumstantial, but I can not see how it is possible to claim it is not needed.
      A maxim I have: if traditionaly consummed may be needed (unless proved otherwise, like meat thanks Doc).

    1. Very interesting study, I wonder if there are more studies like this showing that vitamin K2 might have more benefits than regular K vitamin?

      Dr Greger, I would much appreciate if you would dig further into this whole K2 business. There are a lot of claims out there about this “super vitamin”.

    2. This study is probably only applicable to omnivores- they’re already at risk for heart disease, and were no doubt the subjects of the study. Phylloquinone in a vegan diet may be adequate for the low-risk vegan, especially when you factor in the menaquinone produced by bacteria in our small intestines.

      1. cool, but this was so 1992! lol, here’s a great article, hope it’s not dated, still great though and helped me a lot, it has good references:

        in short, we get enough K on a WFPB diet and as a result we create healthy bacteria to produce the K2 we need and our liver stores what we need for those days when green and cruciferouscous are not plentiful… :)

  6. Your assessment of vitamin K2 is wrong. Read Wikipedia on K2 and the “Calcium Paradox”. If you want to go vegan, you must supplement K2, zinc, taurine and B-12. Your vegan bias is making you look ridiculous. I’ve seen you dismissed as a vegan fanatic. I agree with most of your assessments, but not that we get enough K2 from K1 and vegetables. Calcium from any source without K2 can land in our arteries instead of our bones. Its what’s responsible for “hardening of the arteries” and high blood pressure because the walls of the arteries become less elastic. Start posting results from European publications and knock off your America only bias. Read the commentators on this topic.

    1. You know what you are talking about.

      I’m not sure about taurine yet (still doing my own research, I know it is made in our bodies from cysteine which we can get from plant sources like soy, but maybe we don’t get enough or it isn’t converted enough?), but it would explain why a lot of vegans I know go grey early.

      Add vitamin D to your list and that should be all the supplements you need to take.

      I believe we should always look at the evolutionary science when it comes to our diets. While we are related to chimps the most, we did come from gorillas (technically it was a gorilla ancestor that no longer exists, but you get the point). Gorillas eat bugs like termites (chimps eat termites too, but they also eat meat).

      And what do termites have? B12 and K2 in their guts (they have special bacteria to break down wood).

      And bugs have a high mineral content. For example, mealworms are high in zinc (take that with a grain of salt, finding reliable nutrition information on bugs is hard, even with the internet). And vegans tend to be deficient in minerals like zinc, calcium, and iron. But of the three, I believe zinc is the only one of real concern.

      And of course we get our vitamin D from being in the sun. And maybe taurine from insects? I’m not sure.

      So this solves the mystery behind almost all the deficiencies in a vegan diet (if you are wondering about omega-3, I’ve seen some recent studies saying vegans have enough EPA and DHA in their blood from only consuming ALA sources and gorillas eat dark greens, which have some omega-3, throughout the day. We definitely need more research on humans, but gorillas seem to do just fine on ALA. So unless you eat dark greens 24/7, eat your flax at a minimum).

      So it is either bugs or supplements.

      Dr. Greger, we’ve seen your videos on bugs. We know you think they are a good source of nutrition. But please do a video on the following topics and let us know of any studies you think we are missing:
      Vitamin K2
      Zinc (please do an update saying if we can get enough from just vegan whole foods, because I don’t see the math working out, at least not for men)

      Still, I’m very grateful for all the hard work you’ve done. Thank you Dr. Greger (and his volunteers)!!!

      1. I spoke too soon on the zinc issue. It is possible, but you do have to eat a lot (which I do).

        Per, you need 11 mg for a male and 8 for a female. Before you say vegans absorb less, the study cited in the link above showed vegans having pretty much the same levels as meat eaters.

        Pulling data from, I put my usual meals to the test

        4 cups of brown rice (cooked): 4.8 mg
        1 cup of black beans (cooked): 1.9 mg

        Salad (ignored)
        Apple with 2 TBS of peanut butter: 0.9 mg

        1 cup Oatmeal (cooked): 2.3 mg
        1 cup sweet potatoes: 0.6 mg

        That gets me to 10.5 mg. When you add all the other misc stuff I also eat (mostly fruit and nuts), I’m sure I get the other 0.5 mg.

      2. AlwaysWorking -> A thought provoking response. What Dr Greger has on vitamin K was the scientific consensus as of 2008. It needs updating. Taurine acts as a calcium channel blocker, which is an important function, since calcium build-up is toxic inside the cell, hence the need for magnesium to keep it in solution in the blood stream. My research shows calcium metabolism to be the determiner of aging. It is used to patch up our organs until the organs can no longer function.

        My multi-vitamin has 30mg of zinc which is 2X the RDA. As you note, vitamin D3 is extremely important in its role in calcium metabolism. It gets calcium from the gut into the blood stream. K2 takes over from there. More D3 is being added to multi-vitamins. I hope to see more references to Cochrane meta-studies which much more weight than selecting individual studies to highlight. As far as supplements – a multi-vitamin, vitamin D3 in the winter and omega-3s from fish oil or algae should suffice.

    2. Y’all may have a point, but the fact is that a whole foods plant based
      diet is the best defense against heart disease. Perhaps you want to
      tweak it by supplementing with various nutrients, but not doing so is
      hardly a horrible oversight as no matter what it has been shown that a
      whole foods plant based diet without supplementation is already superior
      against heart disease. The End.

  7. Blindspots?

    Why isn’t this being addressed and why is such an outdated take on vitamin K being presented? It is so important to not only point out the strengths of a vegan diet but the weaknesses.

    It appears that there is more recent info on the CVD impacts of vitamin K2. I’ve been on a very low fat WFPB vegan diet for 2 years yet my CT Calcium Score increased from 152 to 221 event though my LDL is 70, HDL 43. Clearly there are other factors at play. You rarely mention LDL particle size which may be a more important indictor than LDL-C. Vitamin K2 may prove to be as crucial for vegans as B12 since only poorly absorbed K1 is present in the copious leafy greens I eat. Please address these head on.

  8. Hello, dear community!

    In wikipedia, it says that cooked collard greens contain more Vitamin K(1) than raw collard greens. Why is that so?

    Thank you!

  9. Hello everyone!
    I read more and more articles saying Vitamin K2 is critical for health and that our body is not producing enough of it.
    Is that true? do I need to supplement with Vitamin K2?

      1. Nope. Please see my comments. It may be that a wide variety of diets offer K repletion, but it means that anyone consuming only veggies better eat a lot of them, eat them with a fat (to make for bile to allow absorption), and either cook or juice them and they should seriously consider fermenting some.
        Instead of the incorrect assessments of dietary fats where we characterize their bonds (saturated, unsaturated, monosaturated, etc), we SHOULD ask how they affect vitamin K and vitamin K actions.
        Thus, olive oil is a highly bioavailable vitamin K1 (as are canola and soy, but since they are usually GM they have glyphosate which is an antibiotic that impairs gut bacteria, which DO contribute a little to our vitamin K status).
        dK, however, will impair vitamin K actions and it is biomarked by trans fatty acids. Trans fats are NOT the cause of CVD, but they lead to it by impairing vitamin K actions which ARE essential to heart health.
        Saturated fats SHOULD make for proper vitamin K actions if they are from animals which have MK-4 which has about the same life as K1. Only we feed animals weird things and have fouled their fats up with GM foods, etc.
        We have asked the wrong questions and not the right ones about fats/foods.
        We have incorrectly dichotomized animal foods and plant foods.
        It appears that K2 IS an essential nutrient and we simply have missed this due to myopia/truncated thinking/poor definitions/bad clinical test/stupidity.
        I do not endorse the supplements as much as the lost foods. Eat those.
        One of the biggest issues is how to measure vitamin K status. This is defined as how well all vitamin K-dependent proteins are activated. There is no agreed upon test and the vitamin K researchers do not agree amongst themselves.
        I think CAC=0 is vitamin K repletion.
        Having correction coagulation is only part way to repletion, and this represents the newer findings.

  10. Hi Joseph. My understanding was a bit different. What I understand is that vitamin K1, which is present in leafy greens and such, is essential to proper blood clotting function, and is in fact so important that the body recycles it to prevent a shortage. K2 on the other hand is what directs the calcium in our body to the bones and teeth, rather than the arteries. The most concentrated vegan food with K2 is natto. There was a study done in Japan that showed women who ate natto regularly had far less incidents of hip fracture. It was attributed to the natto. The non-vegan population used to get K2 from milk and cheese, however, now that commercially raised cows are given feed of soy and corn rather than being pastured, the K2 is no longer there. Sometimes I wonder if the reason the French have lower incidences of heart disease is their consumption of cheese, as well as wine, which has resveratrol. That’s my own thought, but the Japanese study can be found online.

  11. Came across this site, because I prefer the dry, science based facts, when it comes to food. Thanks for the good work! However, I am a bit disappointed, that most recent findings are not considered or at least mentioned. If there are fancy, serious publications inclining game-changing insights for vegan diets, please at least acknowledge them!

  12. Nope on most of all this. There IS a lot of K1 in veggies, but it is so tightly bound to chloroplasts that very little is absorbed…somewhere in the single digit to about 10%. So citing amounts in a veggie is nice, only you won’t absorb all that. Cooking or juicing seem to make the K1 more available.
    Vitamin K2 in diet, however, is almost completely absorbed.
    There is tons of evidence that vitamin K subclinical insufficiency is very common. But since we have defined vitamin K as vitamin K1 and the role of this family of vitamins as coagulation, we have missed its roles beyond coagulation. And they are HUGE.
    Vitamin K2 is a very interesting topic and one that I suggest you learn a lot more about!
    We make it endogenously in tissues throughout the body (this is new stuff and huge – learn about UBIAD1 and its role in this conversion). The K2 we make this way is the only form of K2 not made by fermentation: MK-4 or menaquinone-4.
    MK-4 is highest in brain and very high in pancreas, kidneys and other tissues.
    This MK-4 binds SXR, and this is also newer info. When it does this, gene expression, the behavior of cancer cells and other effects occur.
    There has been too much emphasis on MK-7, which is high in natto. But natto also has MK-8 and a little K1.
    Our current emphasis on how much of a certain form of K2 is found in a food may miss that the multiple forms of K2 that co-exist may show that it might not be the HIGHEST form amount, but the specific form of K2 that is important.
    The guidelines for vitamin K are completely out of date and do not accommodate the newest data.
    While it is true that K1 is the form of K highest in our current diet (the Western one), we also consume a ton of dihydrophylloquinone (dK) which is made when high K1 oils are hydrogenated. dK fouls up two essential vitamin K actions: it inhibits MK-4 biosynthesis and it inhibits activation of the vitamin K-dependent proteins beyond the coagulation cascade (ones like matrix gla proteins, Gas5, osteocalcin…).
    If you are vegan, you better ferment!
    In the last few decades we have either shunned dietary fats or changed them rather dramatically. In dietary fats we find fat soluble nutrients, which have become the red-headed stepchildren of nutrients: A, D, E and K (well, D is a darling, but D is how the human makes the vitamin K-dependent protein osteocalcin). But K is a very special component of these because you cannot consume too much (unless on warfarin, which will calcify your soft tissues and lead to bad things) since you simply activate those vitamin K-dependent proteins and then you have used the K as much as possible. It does not accumulate to become toxic. It is so essential that there is a way to re-cycle vitamin K for coagulation, but this only helps with this one function of vitamin K and does not address the functions beyond coagulation like bone health, cardiovascular health, cancer cell activity, insulin sensitivity, gene expression and more.
    The cultures with optimal longevity are vitamin K replete.
    Americans are not (mostly, with some exceptions).
    CAC=0 is considered a biomarker that offers the least risk of death or disease and it represents vitamin K repletion, IMO.
    The longer the side chain of a menaquinone (vitamin K2), the more lipophilic and the longer lived in the body.
    those long chain menaquinones are carried by LDL, whereas the shorter chain ones are carried by HDL and K1 is carried by chylomicrons.
    It has been observed that more K2 makes for lower LDL-C and lower TC, which implies that vitamin K status is represented in this misguided biomarker category.
    Look at where we find these: fermented foods, organ meats (esp liver, but also salivary glands, thymus gland, etc), offal, and flat fish or eels (who wallow in bacteria at the bottom of waters).
    We find the shorter-lived MK-4 (remember: not made by fermentation, but found in animal fats and also made by us endogenously) in animal fats, egg yolks.
    Note that we lost all the foods (guts, fermented, animal fats) due to bad dietary guidelines and loss of cultural foods and now we can’t find our butts with both hands.
    Until someone looks at K contents of all foods via liquid chromatography, we will continue to be stupid.
    Until someone assesses the effects of the different forms of K on human health, we will continue to be stupid.
    And until someone understands that our current guidelines are truncated and myopic, we will continue to be stupid.
    BTW, brains REALLY need K2.
    Also, statins and bisphosphonates and NSAIDs inhibit vitamin K2 biosynthesis as well as the dK.
    Thus, Americans are set up to fail due to vitamin K insufficiency and the folks at the vitamin K lab at Tufts still have their heads where the sun don’t shine.
    But you WiLL be hearing about this nutrient/hormone…eventually. It is just tough to find funding when no lucrative drug is the aim.

  13. Read this:
    BMJ openheart
    The health benefits of vitamin K
    They miss so much, but this is a start on admitting that vitamin K plays a role in kidney disease, heart disease, cancer and diabetes.
    Thank goodness we don’t have these as problems…..

  14. As far as I have studied and read, K1 and K2 provide two totally different vital actions. K1 is a coagulant needed for proper clotting due to injury. That is why after a stent is put in, the patient has to take K1 destroying blood thinners such as warfarin. K2 promotes macrophages ability to remove calcium from arterial walls by consuming them and processing for redistribution for bones and/or teeth where they belong. K2 deficiency can be identified by dental tartar or a heart scan calcium test. Possible causation of K2 deficiency is by naturally occurring flora not being able to produce due to meat, sugar and toxic chemicals in artificial sweeteners. I don’t think it would hurt to take K2 supplements derived from Japanese natto for several months after converting to whole plant based diet until the gut flora can naturally resume production of K2.

  15. K2 is different from K1 and is not readily available if you have a Vegan diet. I agree with Dr. Mercola that supplementing is essential especially also if you are consumimg oral Vitamin D3. Calcification of arteries due to lack of Vitamin K2 and the little time of efficiency that Vitamin K1 can provide where it lasts from 1-several hours in the Liver is also another factor to look at. K1 simply aids in clotting and not directing the Calcium to the bones and teeth. I admire Dr. Greger and his site for the wonderful work they do, but I do believe on this particular topic Dr. Greger is relying on old studies and not the most recent data…MK7 is the form of K2 that best meet these needs…

    1. While this idea is oft-repeated on the internet, taking a vitamin D supplement shouldn’t have any effect on whether you take a vitamin K2 supplement unless maybe you are overdosing for some reason. The vitamin D supplement is merely taking the place of vitamin D you would normally get from sunlight exposure. You might as well say “if you take an oral vitamin D supplement or you often go outside during the day, you need to take a vitamin K2 supplement.” And that statement would not be true at all unless you are not getting enough vitamin K2 from other sources.

  16. I’d like to know if Dr. Greger has looked into the vitamin K2 debate any further. I am not a doctor (just a humble nutritionist) but vitamin K1 and K2 have different jobs in our bodies.

  17. Since you mentioned warfarin, I want to know whether folks at risk for clotting should be careful of their vitamin K intake as well. Specifically, I have the factor V leiden mutation. I have never had DVT and am otherwise quite healthy and active – mostly WFPB for years, low BP and cholesterol, walk at least an hour everyday. I do have a varicose vein in one leg, but it’s not usually bothersome.
    Do I need to limit vitamin K intake from food?

  18. This was even with Buddhists who probably limit supplementation.

    These results suggest that, although vegans have much lower intakes of dietary calcium and protein than omnivores, veganism does not have adverse effect on bone mineral density and does not alter body composition.

    Of course, my calcium has a good level. More is not always better. Especially when it is lying around calcifying.

  19. I’ve read around (basically skimming other peoples summaries on the subject) and there are some things I can’t seem to get an answer to:
    1) Do out bodies convert k1 to k2 and if yes, why are there a lot of people refuting this? What can we eat(and how much) to help our bodies carry out this conversion, and what should we avoid?
    2) k2 can be mk4 or mk7. What is the difference, and what vegan food souces can we get these from (and how much to eat)?
    3) where in the UK can I purchase vegan natto (everywhere I’ve found packages it with a sauce containing fish
    4) does saurekraut provide k2, is there a special type to buy and how much do you need to eat a day?



    1. Hi, Tom.
      You can learn a lot about vitamin K, and K2 in particular by reading this article. I don’t know much about the UK market for natto, but you might try a store that specializes in vegetarian and/or vegan products. Failing that, you can make your own natto. With regard to sauerkraut, it is important to get a raw, lacto-fermented type, found in the refrigerated section of the store, rather than on the shelf. You can also make it yourself rather easily. Learn more by reading this article. I hope that helps!

    2. You don’t need to buy vegan natto. You can just buy the regular natto and throw away the sauce packet. Add your own soy sauce. Same situation with instant ramen.

  20. Tom,

    You get plenty of K1 from vegetables and K1 is indeed converted in the body to K2 … but very (too) inefficiently.

    Sauerkraut and some other fermented foods do contain some K2 but not enough. You would have to eat 3 pounds a day.

    Plants do not contain K7 at all. It is made by bacteria that ferment the plants (sauerkraut), the milk (cheese) or the beans (natto).

    MK4 is very similar to MK7, both in structure and function, but MK7 is preferred as a supplement because it is easier to produce (from natto) and it stays active in the body longer than MK4.

    For vegans a supplement (150 mcg/day) or natto (1 spoonful/day) is necessary. The Rotterdam study (mentioned above) showed that even most people on a standard western diet don’t get enough K2.

    There is a lot of info on the subject here:

    And Michael (Mr. Greger, Sir), if you venture here … Please look into this! K2 is like B12. It is only made by bacteria. There is almost nothing of it in plant-based food. It is essential for (cardiovascular) health.

    1. Johaan Spee: From the website you recommended as THE source on K2:

      “Who will benefit from taking Vitamin K2?
      Anyone interested in supporting healthy bones and their cardiovascular system will benefit from taking Vitamin K2. And, in truth, unless you are eating natto every day, you are woefully deficient in Vitamin K2, so start today.”

      It’s pretty obvious they’re into selling the supplement and are part of NattoPharma ASA.

      I’ll keep on relying on eating lots of leafy greens and taking a green drink almost daily for my body’s converting the K1 to K2 as needed. I have no bone problems and am a 61-year-old woman who does not take calcium supplement, not on hormones. I eat high calcium vegan foods and fortified plant milks. And GREENS have shown the best results for proper calcium placement in my body.

  21. Apparently my previous post of this were not accepted due to link? So here goes without link:

    Byers: Regarding this from your linked article: “K2 is lesser-known and harder to obtain in our modern diets. It’s found in dairy products, in egg yolks, and in some fermented foods.”

    That would serve the dairy and egg industries very well, with frightened people feeling that dairy and eggs are vital for human health.

    One would have to eat 10 to 15 eggs per day to get 100% of needed K2, and the only dairy products that have significant K2 are hard cheeses like gouda, not the typical animal milk, yogurt, ice cream and softer cheeses most people eat…those are very poor sources of K2. Even gouda cheese isn’t so much: you’d have to eat 5 oz. of gouda for 100 mcg of K2 and that’s a lot of saturated animal fat and sodium, not healthy. And no one who respects animals or themselves wants to eat gouda cheese or any other animal product. Not when we get the K2 we need from conversion from K1, AND when K2 is produced in our small intestines seemingly regardless of our K1 intake. That was shown in a 1994 HUMAN study (led by Conly JM), NOT with rats, which is meaningful.

    Most cited studies on K2 are rat studies and those are unscientific, to say the least, aside from being terribly cruel. So that human study is something to take seriously.

    A few ounces of raw kale (eaten cooked or raw) provides you with 1100 mcg of K1, and the conversion to K2 rate is estimated at 15%, which yields 165 mcg of K2, more than you need in a day. All leafy greens are great sources of K; eaten with a bit of fat, the conversion to K2 is easy.

    In conclusion, no one who’s eating a healthy vegan diet needs to add another supplement like K2. Only those on junky vegan diets, like anyone on junky diets, need to take an array of supplements including K2.

  22. Dear Dr. Gregor,

    I’ve searched this entire site and there is ONLY this 6yr old article in reference to Vitamin K or K2. Can you possibly do a new update or video??

    I’m particularly interested in Natto(fermented beans) typically eating in the Japanese diet. Apparently Natto has a great amount of pro-biotic bacteria for your gut, K2 for directing calcium to your bones, and may even be good for high cholesterol or triglycerides. Should we be eating this Japanese delicacy on a daily basis? Does it contain the most K2 found anywhere? Or can we just do without it?


    P.S. – Can one of the moderators please forward this comment content to Dr. Gregor?

  23. Hi, Jag Singh. Dr. Greger is very busy writing a new book, but will return to making new videos when it is finished. I know a bit about natto, and have tried it myself. Some people are allergic to it, and may experience anaphylaxis if they consume it. For people taking blood thinners, it is not a good idea, as it may them to bleed too easily. Other than that, it appears to be a safe source of vitamin K2 and other nutrients, from what I can discern from a cursory overview of the research. I will pass your request along to Dr. Greger. If he has not updated the video, it may be that he has not seen any research that would lead him to change his recommendation. Meanwhile, I hope that helps!

  24. In her book “Vitamin K2 and the Calcium Paradox: How a Little-Known Vitamin Could Save Your Life” Aug 27, 2013, by Kate Rheaume-Bleue, she explains the interdependence of vitamins like K1, K2, A, D etc. with Calcium and other substances and hormones and their effects on our health. I would really like to see Dr. Greger taking a look into this research behind all those statements made in this book.
    BTW: Natto, a fermented soy dish and riches source of K2 (mk7) ever reported, which is popular in some parts of Japan, is very easy and cheap to make at home and is about to become a staple in my kitchen can be combined with all kinds of cooked vegetables especially wok dishes or as a perfect basis for creamy sauces. No need to seek for K2 in animal foods (liver, cheese, etc.) or supplements.

    1. Hi, I live in a isolated area, finding natto here is a no go. How do your make Natto? Can you kill your self from making it at home? I know this sounds silly, I don’t want to poison myself while trying to save myself.

  25. Your very much on the right track with both the interaction of the vitamins and hormones and the Natto.

    Speaking of Natto have you seen this study:

    Enjoy your new food experience with natto and check out:, for more ideas.

    Dr. Alan Kadish moderator for Dr. Greger

  26. So, I have read most the comments here. Looked up some of the information you have offered. Pro and con. Have come to the thought that k1 and k2, are the head and tail of the same beast. Each has its own purpose and function. It’s confusing, so to error on the side of caution I will start taking it. My mom started taking it because she was having some attacks like hypoglycemic, did research and found the k2 conection. She started taking it and is feeling better. Thank you all for talking about it.

  27. Do people with a higher risk for blood clots (such as Factor V Leiden or woman on contraceptive pill) need to watch or limit their vitamin K intake?
    Would for example a high consumption of cale increase the risk for blood clots?

  28. I searched several data bases regarding a diet specifically recommended for those with increased clotting risk and other than the restrictions when taking coumadin/warfarin, there are no recommendations for you to limit your Kale or other high Vit K foods. This comprehensive article recommends eating a healthy varied diet without restrictions. You may want to check this out for a full explanation.
    You may also want to check out this article on Vit K, especially the section on Excessive Vit K intake:

  29. I don’t always believe Dr. Gregor. Especially when it comes to vitamin K2 and natto. I been eating natto for many months now. I began by using powdered natto which is not slimy. I bought some natto at the oriental market and all they had was fresh. After some hesitation I tried it and found out I liked it. I strongly recommend you try dried natto first to get used to it. Actually wait till you get addicted to it before trying slimy fresh natto. Natto is very expensive but is as easy to make as yogurt. Ok maybe a little bit harder. Sterility and cleanliness are a must! After you soak the beans you cook them. Steaming is best and filling the water to the very bottom of the steamer is the very best way to cook them. You can ferment them in a yogurt maker. Instant Pot makes an all in one pressure cooker and yogurt maker that enables everything to be done in one pot. You use either natto or powdered spores as starter and the natto needs to breath in order to develop the nutty, coffee like flavor. This requires some practice to master, because sterility and ventilation are complete opposites, but the soybeans are cheap and natto can be made out of any kind of legume so it costs practically nothing to practice. Google some videos on how to make it and also making it with the Instant Pot. Natto Dad has some good videos… Also the spores can be bought really cheap on the internet. You can get 10 x 8, IE 80 packages, enough to make 80 to 240 batches of natto for around 25 dollars or quite a bit more for smaller quantities, (but still cheap) from Amazon. Since I started making natto I have not eaten any non fermented legumes. Not even once! I consume several bowls per day and I have nearly lost my taste for meat. Even my dogs like it! I use a lot of mustard, wasabi and fish sauce to flavor it. Just like they do when they sell those tiny expensive trays; but if you want it vegan ditch the fish sauce and try some soy sauce instead. Dr Gregor is young enough to be my son yet looks old enough to be my father. I attribute most of my youthfulness from years of raw organ meat smoothies but I have practically stopped taking them since I started making natto. BTW I read every one of these posts!

  30. I did a review of the latest studies on Vit K2 and believe you may find the information you are seaching for below. Note the quotes stressing need for further research. While specific studies have shown potential beneficial effects of Vitamin C, note the quoted summary statements stating the need for further research, even for the 2019 article, which can explain why statements recommending K2 supplementation are lacking.

    The role of menaquinones (vitamin K2) in human health
    “There are significant gaps in the current knowledge on menaquinones based on the criteria for setting DRV. Therefore, we conclude that further investigations are needed to establish how differences among the vitamin K forms may influence tissue specificities and their role in human health”

    Vitamin K: Double Bonds beyond Coagulation Insights into Differences between Vitamin K1 and K2 in Health and Disease
    ”Though a new realm to vitamin K seems to be on the horizon, whether it opens up new answers in health and disease remains to be seen. Differences between K1 and K2 merit recognition among national and international regulatory organizations, and remain open to research.”
    Hope this helps.

  31. It’s encouraging that Dr. Kahn is attempting to cite what appears to be published peer reviewed research. but It is disappointing the he does not cite the actual journal article which would allow us to fact-check his statements, and there is just too much rhetoric out there to go try to find what he’s talking about on our own. This is the reason Dr. G ALWAYS cites his sources. Personally, I have a hard time believing that we all suffer from a deficiency of rotting soy beans (natto).

  32. Yes, the study you mentioned is intriguing and for those of us who are plant-based, it suggests that eating more fermented foods may provide health benefits to the other benefits provided by Vitamin K1. There is an updated study regarding this you may want to look at.Vitamins K1 and K2: The Emerging Group of Vitamins Required for Human Health As always it seems more research is warranted so thanks for highlighting this issue.

    1. Dr. Gregor — huge fan.!

      Sounds like there’s a need for a vitamin K-2 update, re healthy calcium placement and plaque.

      Thanks a million, in advance.
      And sorry if it opens up a real can of worms (re fermented cheeses, liver, and omega 3 egg yolks.)

      (Ps: Some of us would really like to know how much we might safely, ur, optimally consume of most of the above, btw. … Even though I strongly suspect you’re going to tell us that we should all just stick to the fermented Japanese soy, and live to be a hundred.)

      Thanks again.
      (Gratitude and respect.)

  33. Vitamin K2 from natto has been studied by the University of Maastricht in the Netherlands and the results are that it brings calcium from the ateries to the bones so clean the ateries in the human bodies and are advised in pill form or from natto.

  34. Hi, Chloe! According to this joint position statement from the Canadian Paediatric Society and the College of Family Physicians of Canada, “Newborns are at risk for vitamin K deficiency bleeding (VKDB) caused by inadequate prenatal storage and deficiency of vitamin K in breast milk.” Presumably, if infants are breastfed by mothers with adequate vitamin K status, this might not be an issue. You can find everything on this site related to vitamin K here: I hope that helps!

  35. I too wish Dr. Gregor would cover the subject of Natto more thoroughly. I have been a long-time vegetarian/vegan (nearly 50 years). For my entire life (actually while still a meat eater too) my fingernails have been thin and brittle, just like my mom’s. We assumed it was genetic. Shortly after I began making and eating my own natto daily, I cant break the things! I actually have to file them to keep them in check. Honestly I was astounded that one thing could make such a difference. I have been a very healthy eater most of my life. I have made absolutely no other changes to diet, supplements or lifestyle. Really nice to know how good it is for our gut biome, bones, skin, and other things. I’m totally hooked.

    1. I should add to the above comment that I have been making and consuming many other fermented foods for many many years, such as sauerkraut, kimchi, and many other vegetables. None of those had the same effect for me as natto.

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