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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

Dr. Cannell on vitamin K2

The Food and Nutrition Board’s Adequate Intake for vitamin K is a ridiculously low 90 mcg/day for adults. One cup of cooked kale has more than 1,000 mcg of vitamin K1. A cup of cooked spinach has more than 800 mcg. And a cup of turnip greens has more than 500 mcg. But that is all vitamin K1.

How do we get our vitamin K2? Diet contains little K2 unless one eats fermented soybeans. There is a tiny amount of K2 in organ meat and hard cheeses, but hardly enough to supply the body with all the K2 it needs. Where is all this extra dietary vitamin K2 supposed to come from?

It is commonly believed that the body cannot make vitamin K2 from vitamin K1 so you have to take K2 supplements. In fact, that is one of the main theses of a recent popular book about vitamin K, called Vitamin K2 and the calcium paradox.

Is that true, do we have to take vitamin K2 or is vitamin K1 turned into vitamin K2 by our bodies?

As early as 1994, researchers had discovered that K1 converted into K2 in the body.

Thijssen HH, Drittij-Reijnders MJ.  Vitamin K distribution in rat tissues: dietary phylloquinone is a source of tissue menaquinone-4. Br J Nutr. 1994 Sep;72(3):415-25.

In 1998, researchers confirmed that K1 is metabolized into K2 and that metabolism had nothing to do with intestinal bacteria. Sterile mice metabolized ingested K1 into K2.

Ronden JE, Drittij-Reijnders MJ, Vermeer C, Thijssen HH. Intestinal flora is not an intermediate in the phylloquinone-menaquinone-4 conversion in the rat.  Biochim Biophys Acta. 1998 Jan 8;1379(1):69-75.

In 2006, researchers confirmed this conversion takes place in humans.

Thijssen HH, Vervoort LM, Schurgers LJ, Shearer MJ.  Menadione is a metabolite of oral vitamin K. Br J Nutr. 2006 Feb;95(2):260-6.

There appears to be two sites of conversion of K1 to K2, one in the intestine and another in peripheral tissues.

Okano T, Shimomura Y, Yamane M, Suhara Y, Kamao M, Sugiura M, Nakagawa K Conversion of phylloquinone (Vitamin K1) into menaquinone-4 (Vitamin K2) in mice: two possible routes for menaquinone-4 accumulation in cerebra of mice. J Biol Chem. 2008 Apr 25;283(17):11270-9. Epub 2007 Dec 14.

Recently, the mechanism by which the body turns vitamin K1 into vitamin K2 was clarified. It occurs through an intermediary molecule, vitamin K3, which is made in the intestine from vitamin K1.

Hirota Y, et al.  Menadione (vitamin K3) is a catabolic product of oral phylloquinone (vitamin K1) in the intestine and a circulating precursor of tissue menaquinone-4 (vitamin K2) in rats. J Biol Chem. 2013 Sep 30.

I cannot put my hands on it now, but I read a paper that actually showed K2 content in peripheral organs is higher after vitamin K1 ingestion than K2 ingestion.

It seems that it could be the case that 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.

Does vitamin K2 and supplementation still have a role in clinical nutrition? I think so. There are trials underway looking to see if vitamin K2 can help with a variety of conditions. It may be very important for bone health. There has also been a trial that shows it’s more efficacious than vitamin K1 in raising IGF-1 levels.

Cannell J. RCT: Vitamin D, calcium, and vitamin K’s effect on activity in postmenopausal women. www.vitamindcouncil.org, April 30, 2012.

However, as far as getting enough vitamin K2, the best thing to do is eat your greens.

  About: John Cannell, MD

Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, emergency physician, and psychiatrist.

6 Responses to Dr. Cannell on vitamin K2

  1. Mariabrent says:

    Dear Dr. Cannell,

    I just read above about Vitamin D, Vitamin K, and IGF-1. A little alarm for me, since IGF-1 promotes the growth of cancer cells. (I avoid sugars to keep insulin growth factors low since I have a history of stage III breast cancer). I know that vitamin D seems to help prevent cancer and even perhaps metastasis. Can you provide more information or clarification, please.

    Maria, a long time member and supporter (I tell the BC group I belong to that I am an emissary of the sun god come to tell them to get vit D levels checked and aim for levels above 50, and many have done so, and have become emissaries themselves)

  2. Based on comments by Dr Mercola http://www.mercola.com who said that seniors have decreased ability to make vitamin K2. I take bone calcium reducing drugs so I found it impossible to build bones with just calcium citrate, vitamin D3, and eating green vegetables. I started taking vitamin K2 and finally was able to build bone. Jim

  3. Rita and Misty says:


    I encourage you to consider researching the vitamin D/Iodine/selenium connection to breast cancer.


  4. john9546 says:

    Thank you for discussing Vitamin K2. I have added foods that have K2; grass fed chicken eggs, and various cheeses like brie. I also supplement. Folks, please try to get a copy of Dr. Kate Rheaume-Bleue book referenced above “Vitamin K2 and the calcium paradox”. It is excellent on the K2 subject. Also search for Kate Rheaume-Bleue on YouTube for much more information. One good one is an interview with Dr. Mercola:

  5. John Cannell, MD says:


    The association of high IGF-1 levels with cancer only appears to be true in those with a low 25(OH)D level.



  6. showmeaschematic says:

    Dr Cannell,
    Please forgive me if I seem very skeptical and critical. I have spent years researching information for my personal health, and, given the amount of confused, unscientific, and/or frankly malicious so called research out there, I must be diligent.

    It seems that all the studies, except one are on rodents. Is it valid to extrapolate to humans ? In the one human study, the conversion took place in the gut, so why would that eliminate the possibility that it wasn’t a microbially mediated conversion ?

    I do accept the possibility that we possess the ability to convert, but, is it not likely that very few people have the quality of diet to provide good levels of K1 as a feed stock for conversion ?

    The way I do the final test of validity for any health shift I make, is to try it…..pick some result that I can fairly clearly monitor….and see what happens. In the case of K2, I chose my teeth. I have an intersection of expertise from Dr Weston Price, Kate Rheaume Bleue, and a book called ” Cure Tooth Decay ” by Ramiel Nagel that all indicate that sufficient and balanced vitamins D, K2 and A make teeth immune to decay plus enable the body’s ability to grow new dentine to repair tooth injury. These supplements start a positive flow of mineral, from the core of the tooth, out through the porous shell. I started taking 360 micrograms of K2-7 from natto, and 10,000 IU’s of vitamin A from Halibut oil almost a year ago, along with my regular 8,ooo IU’s of Vitamin D. ( I test regularly at about 70 ng/ml. ) Within about 6 months, I noticed that my 64 year old teeth became robust, not sensitive to heat, cold, impact or vigorous brushing like they used to be. My wife, who also took supplements, was able to stop using Sensodyne toothpase, which she formerly had to because her teeth hurt so much that she was having trouble brushing.

    Primitive and not rigorous science, but good enough for me. I am convinced that these supplements have helped my teeth. That tells me that I was suffering from an insufficiency. It also gives me a better level of confidence that the information I was going on is basically sound. Now, if I eat chard, spinach, or kale every day of the year… then maybe I would have converted some of the resultant K1 to K2 and achieved the same result, so I am not offering this as disproving the results you quote, just that, in our northern climate, I can only grow these greens for less than half the year ( and I do ). I rarely buy them in the grocery store, because I distrust either the pathogens, or the pesticides that big agri puts on them, and I can’t afford it anyways on my pension. Whatever the reason(s), it sure seems I wasn’t getting enough, and supplementation was a simple way to solve the dilemna.

    I have noticed a significant change in my heart as well. I am able to stress myself physically, even though I may be a bit out of shape at the time…. in say vigorous digging in the garden, or something like that….. without getting the sort of nauseous, faintish, feeling that I used to…. and that I can sort of keep going, “leaning ” in a way on my heart, which I can feel pumping strongly, without complaint of any kind. This is new, though, I certainly can’t tie it necessarily to my supplementation…. still it is different.. and a positive development, and would be consistent with Kate’s claim that plaque deposits can be removed. Subjective, I know, but just thought I would share that impression.

    I do intend to keep on this way, so will blog in anything useful I notice. The only change I am considering, is perhaps lowering the amount of Vitamin A to 5,000 IU’s per day, as I am pushing the upper limits, I think, for maybe no good effect. I haven’t seen any clear advice on
    exactly what the optimum ratio among these supplements is. Your thoughts would be appreciated.