What are the best sources of vitamin K?

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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?

Answer:

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 25 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

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  • Tony

    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.

  • adawe

    mk4 isn’t same as mk7 either. both are k2, but different forms

  • colonyofcells delacruz

    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.

  • Sharon

    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.

  • Jeremy Nagel

    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 VitaCost.com).

    http://journals.cambridge.org/action/displayAbstract;jsessionid=8485084EC3B24DE5762B43FB087A1FBF.journals?fromPage=online&aid=8894242

  • Luc

    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:) )

    • 718Ken

      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.

    • Arjan den Hollander.

      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 ^^.

  • Alain Lachance
    • Selina

      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”.

  • Joe Tilman

    Any comment about the fact that natto is also replete with B12?

  • folk_singer

    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.

    • AlwaysWorking

      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)
      Taurine

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

      • AlwaysWorking

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

        Per VeganHealth.org, 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 Nutritiondata.Self.com, I put my usual meals to the test

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

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

        Dinner:
        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.

      • folk_singer

        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.