Vitamin K2: The Missing Nutrient

May 6, 2008 in Cancer, Food & Nutrition, Heart Disease | 107 comments

cheeseA study recently published by the European Prospective Investigation into Cancer and Nutrition (EPIC) has revealed that increased intake of vitamin K2 may reduce the risk of prostate cancer by 35 percent. 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 now prostate health.

Unfortunately, many people are not aware of the health benefits of vitamin K2. The K vitamins have been underrated and misunderstood up until very recently in both the scientific community and the general public.

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 vitamin K2′s role in the body extends far beyond blood clotting to include protecting us from heart disease, ensuring healthy skin, forming strong bones, promoting brain function, supporting growth and development and helping to prevent cancer – to name a few. In fact, vitamin K2 has so many functions not associated with vitamin K1 that many researchers insist that K1 and K2 are best seen as two different vitamins entirely.

A large epidemiological study from the Netherlands illustrates this point well. The researchers collected data on the vitamin K intakes of the subjects between 1990 and 1993 and measured the extent of heart disease in each subject, who had died from it and how this related to vitamin 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 vitamin K2 intakes were 52 percent less likely to develop severe calcification of the arteries, 41 percent less likely to develop heart disease, and 57 percent less likely to die from it. (Geleijnse et al., 2004, pp. 3100-3105) However, intake of vitamin K1 had no effect on cardiovascular disease outcomes.

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, such as the soft tissues.(Spronk et al., 2003, pp. 531-537) In an acknowledgment of the different roles played by vitamins K1 and K2, the United States Department of Agriculture (USDA) finally determined the vitamin K2 contents of foods in the U.S. diet for the first time in 2006. (Elder, Haytowitz, Howe, Peterson, & Booth, 2006, pp. 436-467)

Another common misconception is that human beings do not need vitamin K2 in their diet, since they have the capacity to convert vitamin K1 to vitamin K2. The amount of vitamin K1 in typical diets is ten times greater than that of vitamin 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 vitamin 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 vitamin K2 in the diet is that epidemiological and intervention studies both show its superiority over K1. Intake of K2 is inversely associated with heart disease in humans while intake of K1 is not (Geleijnse et al., 2004, pp. 3100-3105), and vitamin K2 is at least three times more effective than vitamin K1 at activating proteins related to skeletal metabolism. (Schurgers et al., 2007) And remember that in the study on vitamin K2′s role in treating prostate cancer, which I mentioned at the beginning of this article, vitamin K1 had no effect.

All of this evidence points to the possibility that vitamin K2 may be an essential nutrient in the human diet. So where does one find vitamin K2 in foods? The following is a list of the foods highest in vitamin K2, as measured by the USDA:

Foods high in vitamin K2

  • Natto
  • Hard cheese
  • Soft cheese
  • Egg yolk
  • Butter
  • Chicken liver
  • Salami
  • Chicken breast
  • Grond beef

Unfortunately, precise values for some foods that are likely to be high in K2 (such as organ meats) are not available at this time. The pancreas and salivary glands would be richest; reproductive organs, brains, cartilage and possibly kidneys would also be very rich; finally, bone would be richer than muscle meat. Fish eggs are also likely to be rich in K2.

It was once erroneously believed that intestinal bacteria are a major contributor to vitamin K status. However, the majority of evidence contradicts this view. Most of the vitamin K2 produced in the intestine are embedded within bacterial membranes and not available for absorption. Thus, intestinal production of K2 likely makes only a small contribution to vitamin K status. (Unden & Bongaerts, 1997, pp. 217-234)

On the other hand, fermented foods, however, such as sauerkraut, cheese and natto (a soy dish popular in Japan), 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. A recent study demonstrated that MK-7 increased the percentage of osteocalcin in humans three times more powerfully than did vitamin K1. (Schurgers & Vermeer, 2000, pp. 298-307)

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. As mentioned previously in this paper, he found that the Activator X concentration varied 50-fold. Animals grazing on vitamin K-rich cereal grasses, especially wheat grass, 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 top soil that had such 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.

New research which 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.

Recommended links

  • On the Trail of the Elusive X-Factor
  • The Vitamin You Need to Prevent Prostate Cancer
  • K2 Associated with Reduced Risk of Coronary Heart Disease


Bryan - oz4caster July 17, 2008 at 9:57 pm

Excellent article! I’d be interested to find out if kefir has more K2 than the milk it is made from. I would not be surprised if it did.

I added the little bit of K2 data for food that I could find to my Excel dietary nutrition calculator. Most of what I found came from Chris Masterjohn’s WAPF article on K2 in Wise Traditions.

Chris July 17, 2008 at 11:19 pm


Thanks for your comment.

Kefir definitely has more K2 than milk, as K2 is a product of bacterial fermentation. Natto, a fermented soy product, is the highest natural source of K2.


Jeanie January 19, 2009 at 6:40 pm

Hi, Does any one no where I can buy vitk2 Natto that is non gmo and certified organic? I just read an article stating that many of the soy beans grown in the US that have been sold to Japan have tested positive for gmo even though they were organic. I would like to buy the food instead of the suppliment in hopes that it is cheeper but also pure. 

Peggy February 5, 2009 at 9:55 pm

I have found an organic natto at our local Japanese market, Nijiya Market, a chain in CA. They also feature several non-GMO versions. You could also make your own (Gold Mine carries the starter, as does Nijiya Market). The food is the best way to go if you can eat it. Then you also get nattokinase benefits (helps dissolve clots) as well as the K2. About 1/4 of a 100gm pkg eaten every other day should protect you well enough due to the MK-7 long lasting form of K2. BTW, natto can be frozen and re-frozen without significant loss several times.

Carol Hitchcock February 9, 2009 at 9:43 am

So grateful for the info on K-2.  I’m just discovering this and have just discovered at the age of 67 from a cat scan that I have minimal calcification and minimal calcium deposits in my main aeorta in the stomach area.  It is so satisfying to have an answer and unfortunately most doctors don’t seem to offer this as they are more of a reporter and less of a problem solver or researcher.                                                  Thanks so much!                                 Carol 

Jean February 9, 2009 at 6:21 pm

Hi, I have bone spurs on my heals. It would be great if vk2 worked to heal them. I quit my job as a PE teacher becuase of the pain. I am just hoping to find some that isn’t made from gentically modified soy beans.

rose tubbs February 13, 2009 at 7:34 am

I have been on HBP medication which includes calcium chanel blockers (admittedly a small dose) for nearly 3 years -monitoring shows blood pressure now well controlled but I hate taking pharmaceutical drugs. Dr is very loathe to give me info on this drug and I have always wondered what would be the natural alternative. With your info it seems to become a bit clearer and I would lke to take a little K2 or at least eat sauerkraut and more cheese & egg yolk. What do you think?

Chris February 13, 2009 at 1:56 pm


I’m not aware that K2 has any specific effect on blood pressure.  While I can’t provide any medical advice, as I’m not a doctor, I can tell you that there are several ways to lower blood pressure naturally, including stress reduction, meditation, acupuncture, and dietary therapy.  Meditation is particularly effective, and is completely non-invasive – not to mention free!

carl February 14, 2009 at 7:49 pm

does soy yogurt have k2 as it is a fermented soy product?

carl February 15, 2009 at 8:02 pm

That is hard to believe as they eat a lot of soy in China and it doesn’t look like they have problems with feritlity as it is the world’s most populus country; my soy yogurt is organic soy;

Chris February 15, 2009 at 11:19 pm


It is a common misconception that Asians eat “a lot of soy”.  In fact, that’s not true.  Soy has traditionally been used as a condiment in Asia, and even then it was carefully prepared (through long fermentation) to destroy the phytates found in soy that inhibit nutrient absorption.

Many vegetarians in the USA, and Europe and Australia would think nothing of consuming 8 ounces (about 220 grams) of tofu and a couple of glasses of soy milk per day, two or three times a week. But this is well in excess of what Asians typically consume; they generally use small portions of soy to complement their meal. It should also be noted that soy is not the main source of dietary protein and that a regime of calcium-set tofu and soymilk bears little resemblance to the soy consumed traditionally in Asia.

Perhaps the best survey of what types/quantities of soy eaten in Asia comes from data from a validated, semi quantitative food frequency questionnaire that surveyed 1242 men and 3596 women who participated in an annual health check-up program in Takayama City, Japan.  This survey identified that the soy products consumed were tofu (plain, fried, deep-fried, or dried), miso, fermented soybeans, soymilk, and boiled soybeans. The estimated amount of soy protein consumed from these sources was 8.00 ± 4.95 g/day for men and 6.88 ± 4.06 g/day for women (Nagata C, Takatsuka N, Kurisu Y, Shimizu H; J Nutr 1998, 128:209-13). 

According to KC Chang, editor of Food in Chinese Culture, the total caloric intake due to soy in the Chinese diet in the 1930′s was only 1.5%, compared with 65% for pork.

Compare that to the 220g that the average American consumes in a single 8 oz. glass of soymilk.  What’s more, almost all processed food these days has some form of soy in it, whether in the form of soybean oil, soy protein, soy flour or soy lecithin.  The reality is that most Americans – especially those who are “health conscious” – are consuming far more soy than Asians ever have, and far more than it is healthy to eat.

Did you read any of the information I linked to?  I’d really recommend you do that before making up your mind one way or the other.  Here’s a direct link to the study which demonstrated a significant decrease in sperm count in males consuming as little as one cup of soy milk per day.  It was published in a major, peer-reviewed journal by a reputable researcher working at the Harvard School of Public Health. 

I’ve written about other dangers of soy consumption on this blog (I provided the link in my previous post).  There is overwhelming evidence that soy is harmful too our health in the quantities we’re consuming it in.  This is true whether the soy is organic or not. 


Judy March 16, 2009 at 1:24 pm

As a strict vegan where would I get the most benefit from K2 vitamin.  I don’t consume meat or dairy.

Judy March 16, 2009 at 1:40 pm

Does this have to be made or can it be purchased somewhere like whole foods markets, etc.  How do you prepare it?

Chris March 16, 2009 at 1:46 pm

Both natto and sauerkraut can be purchased at health food stores.  It’s important to get organic natto made from non-GMO soy.  See the posts earlier in this thread for more info.

roni May 8, 2009 at 6:32 pm

hi chris,  thank you for this information! until recently i was unaware of the research findings on k2.  i wonder if you have any idea what a good amount of k2 per day is, and what is the designation for it? units? micro or miligram?  and lastly, any idea of the amount of k2 in trader joe’s organic low fat yogurt?  does the lower fat content lower the k2 level?
thanx for your reply.

roni May 8, 2009 at 6:48 pm

hi again chris, i have another question for you. what do you think of bragg’s liquid amino’s?    thanx.

Ben Foster May 17, 2009 at 4:02 pm

Dear Chris,
I’ve only recently come across the K2 studies. They raise a series of questions for me. My major concern is prostate cancer, and I am intrigued by the studies showing a reduced danger of advanced prostate cancer for men who consume more K2. But the sources for K2 are primarily animal, especially dairy. This finding directly disagrees with many other recent finding that correlate high dairy intake with high risk for prostate cancer. The Japanese, who eat little dairy, have one quarter the prostate cancer that we Americans suffer. In countries with high dairy intake, prostate cancer rates are also high. Colin Campbell in The China Study asserts that diary interferes with the body’s use of vitamin D, and that high dairy intake causes an enormous increase in aggressive and advanced prostate cancer. Campbell recommends a vegan diet–no animal based food at all. He claims that population studies demonstrate that vegan populations do not suffer from the  high incidence of cardiovascular disease and cancer that we in the West do with our diets heavy on animal protein. Campbell asserts that it is the protein especially in dairy that makes it so harmful to Western diets. In the recent study of K2, cheeses, especially Gouda and Edam, were recommended as sources of K2. Since this contradicts so directly the findings of Campbell, I am puzzled. But also hopeful. Because of my prostate cancer fears, I have given up nearly all dairy, and the part I miss most is cheese. How I would love to find out that at least some cheeses come in with  a clean bill of health in regards to the prostate. My other questions are these: does miso qualify as a source of K2? What about supplementation with nattokinase? Nattokinase supplements are easy to come by, but natto is scarce in these parts, and I’m not eager to make my own. Sorry to throw so many questions at you. Credit it to your raising important issues.

Ben Foster May 17, 2009 at 4:06 pm

Chris: Re:K2 studies showing reduced prostate cancer risk. But the studies point to dairy sources of K2, e.g.cheeses. Dairy is implicated in prostate cancer. So: Is it good or bad for prostate health to eat cheeses? And what of nattokinase supplements instead of natto? Does miso fit into the K2 picture?

KimC. July 7, 2009 at 1:30 pm

Oh, I hate to be a bother when you’re busy trying to complete your studies, but this is of great interest to me as my husband suffers from DISH – Diffuse Idiopathic Skeletal Hyperostosis – essentialy calcification of the anterior ligaments of the spine. Although quite rare in a man of his age (he’s only in his late 40′s), his Rheumatologist has told him that dietary changes would not make a difference, but I wonder if K2 supplementation could be of assistance here.

I’ve been unable to find the original Spronk research article quoted in your post and any assistance in locating it, if at all possible, would be greatly appreciated.

Thanks so much for your terrific blog.
Kim C.

KimC. July 7, 2009 at 3:48 pm

Wow, thanks so much for your prompt and helpful reply, Chris. I had no idea that “google scholar” existed. And yes, it was that sentence that caught my attention: 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, such as the soft tissues.(Spronk et al., 2003, pp. 531-537
Thanks again and best wishes to you in your academic endeavors.

Sam July 27, 2009 at 8:13 pm

I tried to warn people at work about danger of eating soy products, they did not belive me. After I emailed this link, many had a second thought, especially pregnant women.
About cheese. After reading a book
A Cancer Battle Plan by David J. Fraham
I stopped eating cheese in any form.

Mona August 4, 2009 at 11:12 pm

My mother has been k2 for 3 months. She has recently noticed black patches on her face and arms, swelling on one side of face and inside mouth, pain behind her ear leading to her neck. Could this be a side effect of K2? She is on statins, and aspirin.

Ed September 1, 2009 at 8:19 pm

I think marrow also has lots of K2, so a good marrow bone broth ought to be a good diet addition. I’m still looking for a good reference, though, to support that.

Alan Reith September 6, 2009 at 3:25 am

What is the recommended minimum intake of Vitamin K2 per day for and adult male (me) with calcium in the arteries? Doctor has put me on Caduet (a statin I believe) which is giving me several unwanted side effects.
I have sourced Natto (Nippon Food Supplies) and am planning to replace the Caduet with it.
Any comments would be greatly appreciated.

Sharon Hunt November 23, 2009 at 11:24 am

Hi Chris,
Do you think if I made homemade yogurt from organic whole milk, and consumed around 4 oz a day  that I would get the necessary vit k2 amounts in my diet? I am kind of confused about the relationship between milk from a grass fed cow (where in the world can you buy milk from a grass fed cow in So. CA?) and the traditional corn fed cow milk (which I think is probably where all of our milk in the city comes from… even organic milk?). I am a lacto/ovo/ fish vegetarian.  I am also genetically predisposed to develop osteoporosis. Thank you for providing this valuable information!!!


admin November 23, 2009 at 11:29 am


You can get grass-fed raw milk at Whole Foods in Southern California. That’s what I would recommend. But milk isn’t a sufficiently high source of K2. Raw, grass-fed butter would be higher, which you should also be able to buy from Whole Foods (Organic Pastures is the brand). Fermented cod liver oil with butter oil would also be a good choice. It can be ordered here. Finally, anything else fermented like kefir (which you can also make with the raw milk – do a Google search), raw sauerkraut (buy at Whole Foods or make yourself) or kim chi will be high in K2. You can also supplement with K2 using the MK-4 form. and other online companies have it.

Sharon Hunt November 23, 2009 at 1:40 pm

You are “the bomb”  Chris… thanks!!!

Kris November 29, 2009 at 9:14 pm

Why not just take MenaQ?

Roy Hartsell February 24, 2010 at 10:21 pm

I have read and read and nothing about K-2 and stents. Can I take MK-7K-2   with stents in my heart? Why does it say on the warning label not to take if you are on coumadin or other blood thiners? Thank you .Roy.

admin February 24, 2010 at 11:47 pm

The warning reflects a misunderstanding of the function of K2 in the body. Whereas K1 is preferentially used by the liver to activate blood clotting proteins, K2 is preferentially used by the other tissues to place calcium where it belongs, in the bones and teeth, and keep it out of where it does not belong, in the soft tissues (reference).

As to whether it’s safe to take K2 with a stent, I don’t see why it wouldn’t be. In fact, vitamin K2 has been shown to reverse arterial calcification in rats. Nevertheless, you should check with your doctor on this question.

Sandra Mennella April 4, 2010 at 10:35 am

Since I have been taking Vit .K2 I am aware of a skin rash similar to hives.  Since my bones are deficient I have been taking an unusually high dose of K2 5000 mcg, Menatetrenone source.  I have read much information in your documentation but find no reference to  this subject.  Could you answer this concern for me.

Chris Kresser April 4, 2010 at 10:53 am

I’ve never heard of hives as a response to high doses of K2, and I can’t think of an obvious mechanism, so I’m afraid I can’t help you.

Scott April 20, 2010 at 11:03 am

Does tempeh provide a similar K2 benefit as does natto, being a fermented product as well?

Chris Kresser April 20, 2010 at 11:33 am

Natto is the only fermented soy product that contains a significant amount of K2.

Barbara June 10, 2010 at 11:27 pm

Great info on K-2. I’ve been diagnosed with bone spurs in neck, spine, shoulder and hip and have severe pain. I don’t know if the bone spurs can be dissolved, but the remodeling of the bone via calcuim, D-3 and K-2 should be most helpful shouldn’t it?

I’m not keen on taking Natto, have heard that taken in natural form it’s totally nasty tasting. I think I’d go with Kefir, sauerkraut, and the other recommended foods. I have recently been drinking pristine raw milk from grass fed Jersey cows. Too soon to notice any difference in calcium increase.

veronica June 20, 2010 at 10:42 am

Hi Chris,I am in the process of getting dental implants but the bone graft I had done 4 months ago is not hardening as I hoped and was wondering if k2 with d3 would help.
Thank you

Chris Kresser June 20, 2010 at 11:49 am

I imagine it would, since K2 regulates calcium metabolism and directs it to the bones and teeth rather than the soft tissues.

ben nguyen June 27, 2010 at 10:51 am

Natto (fermented soy beans) would seem like the perfect source for vitamin k2…   However, isn’t soy particularly bad?
I’m guessing blood tests could be done to check k2 levels.. what would be a healthy number to shoot for?

Chris Kresser June 27, 2010 at 11:02 am

Unfermented soy is bad.  Fermented soy is fine in moderation.  Natto is indeed the best source of K2, but most people can’t tolerate the taste.

I haven’t heard of a reliable blood test for K2.

ben nguyen July 1, 2010 at 1:22 pm

Tried natto, didn’t like the taste :(
Did find perhaps some k2 source alternatives:

Chris Kresser July 1, 2010 at 1:46 pm

Either of those would be fine. Thorne and GP are both good companies.

ben nguyen July 2, 2010 at 10:30 am

Neither has K2 in the MK7 form that comes from fermentation (natto etc)… they both contain K2 of the MK4 type (i.e. K2 that’s been synthesized by animal tissues)
So that begs the question, which is better MK4 vs. MK7?
Jarrow for example has an MK7 supplement:
Interesting Study cited in this thread:

Chris Kresser July 2, 2010 at 11:55 am

That’s a controversial topic, Ben. MK4 is the form synthesized from K1 by humans for their own use. Although they’re similar in function, MK-4 has effects on gene expression in bone tissue that MK-7 doesn’t have. I recommend using MK4 for this reason. See this post for more information.

ben nguyen July 2, 2010 at 11:13 pm

Yes, according to that great post, it does seem that the effective of MK-7 has not been studied yet…
The comments to the post were also great, someone pointed out that Life Extension has one product with both MK-4 (1mg) and MK-7 (1ug)!  So I think that might be a good way to hedge my bet!

Patti Hill July 30, 2010 at 2:54 pm

Hi Chris,
I am thinking of adding K2 to my vitamin regimen.   I have been taking over the counter calcium with vit. D for over 30 years which was prescribed when I had lupus.  It has been gone for 20 years but I still take calcium for mild osteopenia.   Over the years, I have developed many calcium deposits in my thighs and torso.  The doctors say it is nothing to worry about and they have no answer as to how to stop them or get rid of them.  Do you think the K2 might possibly help to get rid of the calcium deposits or keep new ones from occuring.  Also I eat a lot of store made saurekraut, not canned.  It is considered fermented?  I also eat 8-10 Egglands free range eggs a week.  Do you think the sauerkraut and eggs might provide enough K2 without the need to supplement? 
Thanks for any advice.


Chris Kresser July 30, 2010 at 5:32 pm


Sauerkraut must be raw in order to be of benefit. The stuff they sell in normal supermarkets is pasteurized, which kills the beneficial bacteria. Health food stores in many areas do sell raw sauerkraut, or even better, you can make it yourself and save a ton of money.

Eggs – even “free-range” supermarket eggs – are not as high in K2 as some fermented foods like natto and hard cheese. Butter is another good source, but it must come from grass-fed cows, and that’s not easy to find in some places.

With your history you might consider the fermented cod liver oil / butter oil blend from Green Pastures. It has vitamin D, vitamin A and vitamin K2 as well as EPA and DHA together. It’s actually one of the few maintenance supplements I recommend everyone take, because of the balance of nutrients it contains. A, D & K2 work synergistically to promote healthy bones.

Patti Hill July 30, 2010 at 7:53 pm

Thanks Chris.  I will look at their website.  You say this one of the few supplements you recommend everyone take.  Are there others and, if so, what? 

On a totally unrelated issue, I have had low WBC counts for the last 10 years, possibly more, and it is low enough that doctors wanted to find a cause but, as yet, have not found one.  Do you have any knowledge on this?  My internet searches have not helped me and I’m not sure I should even be too concerned about it.  One person said that low WBC are not a diagnosis but simply a lab result that might have meaning, so don’t worry about it.   Do you have any thoughts?


Chris Kresser July 30, 2010 at 8:52 pm

It depends on the person.  For the average, generally healthy person the fermented cod liver oil / butter oil blend is it.  Magnesium is difficult to get with a paleo/primal type diet, which is often what I suggest people follow, and many people are deficient in it so I may suggest that as well.  Overall my preference is always to obtain the nutrients we need from food, or at least food-based products like cod liver oil, when possible.

Low WBC may indicate a chronic viral or bacterial infection, or it may simply be genetic.  If you’ve low WBC your whole life, and you aren’t symptomatic, I wouldn’t worry about it.

Linda July 31, 2010 at 8:36 am

I’ve just come across your site & this thread on K2. I wonder if you’d share you thoughts on a a bit of a challenge we face at times in my health food store — how to best inform people who are taking blood-thinning drugs about the benefits of K2. We now just suggest that they ask their doctor about how to balance the K2 & the warfarin. We realize of course that virtually no PCP’s are informed on this.
     I myself take K2 & D3 daily, to help stop my body from taking calcium from my bones & then depositing it in joints, etc.

Chris Kresser July 31, 2010 at 10:02 am

There are studies demonstrating that rats treated with high doses of warfarin develop arterial calcification, and that K2 protects against this. It can be speculated that humans who take warfarin also develop some degree of calcifications in their arteries, predisposing these patients to heart attacks and strokes. Unfortunately I haven’t seen human studies confirming this. On the other hand, the Rotterdam Study showed that K2 intake is associated with a significant reduction in CVD. And this study shows that K2 does prevent arterial calcification. So, although we don’t yet have all of the research we’d like to have on this subject, I think you can piece together a pretty strong argument for taking K2 with warfarin. The caveat is that K2 will probably lower the INR to some degree, so the PCP would need to monitor that.

You could also educate them on using EPA & DHA at high doses as an alternative to warfarin. Studies have shown similar CVD-preventative effects, and of course EPA & DHA have benefits warfarin doesn’t have.

ben nguyen August 12, 2010 at 8:59 am

A synthetic k2 (mk-7 only) that is more absorbable?

Jane August 14, 2010 at 4:01 pm

I am on a Calcium, Vitamin D supplement for thinning bones. It also has 45mcg of vitamin K2. Does this cause blood clots, since that what I understand vit K does? 

Chris Kresser August 23, 2010 at 6:32 pm

Vitamin K2 and vitamin K have different effects. K2 primarily regulates calcium metabolism (i.e. makes sure calcium goes into the bones and teeth where it belongs and not the soft tissue), whereas vitamin K has a stronger effect on coagulation.

Ann September 1, 2010 at 7:52 pm

Chris, thanks for your information on K2.  I am researaching benefits of K2 for my situation.  I did not have osteoporosis until I had been on Advair for a few years for COPD from chronic bronchitis.  I have been on Actonel for 1 yr and 7 months.  Just had a bone density test that showed I have declined again, 12%.  Now at -3.3.  I have taken calcium supplements for most of my adult life and have been taking D3 and magnesium for several years.  I have a history of DVT, so I take Persantine, which is not a blood thinner, but keeps my platelets from sticking together.  I transitioned to vegan and have been free of animal products for one year.  I do not eat the high fat raw, but try to eat mostly fruit, veggies, legumes, and small amount of whole grains and try to keep fats low (nuts and EVO).  I am wondering if 1) K2 is right for me,  2)  if my diet contributed to the bad report,  3) would K2 help if I still have to take Advair (steroids).  Would Kefir have K2?  What about rejuvalac?

Chris Kresser September 1, 2010 at 8:43 pm

Ann: I don’t advocate a vegan diet for multiple reasons, and this is one of them. It’s impossible to get the nutrients (from food) necessary for optimal health with a vegan diet. I’ve written about that elsewhere on the blog. My recommendation for dealing with your problem would include a diet rich in grass-fed animal products, fermented cod liver oil (supplying A, D, K2, E and other quinones in their natural, whole-food form), and regular consumption of whole, fatty fish like salmon. K2 is certainly right for you, as is a whole-food form of D and A. Kefir probably does have some K2, since it’s fermented – especially if made with milk from grass-fed cows. Sauerkraut is another potential source.

Ann September 2, 2010 at 11:31 am

Chris, thank you for you reply.  This info has helped.  I will make diet changes.  I know that I am not getting enough calories with vegan diet, but in going low-fat vegan, I was trying to lower cholesterol which has been high for years; plus, acidic animal foods supposedly make osteooporosis worse.   I am allergic to seafood, so can’t do fish or cod liver oil.  I do have Ann Wigmore’s books with instructions on how to make sauerkraut.  It is not easy  to find the right way to eat to obain better health.  This blog has offered more information that just reading an article would not provide.  Thanks again!

Chris Kresser September 2, 2010 at 11:33 am

There’s no need to lower cholesterol in most cases.  Read these articles and watch the videos.

jackie September 2, 2010 at 2:25 pm

Hello, Chris! I just started taking the TriK Vitamin K supplement, and was wondering if the multi-vitamin that I am taking offers sufficient D3 (5,000 IU) and A (5,000 IU) to aid in absorption? I also take a Krill Oil supplement once daily. I am taking the supplement becuase I am genetically predisposed to heart problems and osteoperosis (both sides of the family) – I am 30 but don’t want to take any chances with problems down the line. Just wondering if this is a good idea? Thanks for your time!!

Chris Kresser September 2, 2010 at 2:31 pm

You should be fine. I prefer getting A & D from natural, whole food sources like fermented cod liver oil (from Green Pasture), but in terms of dosage you’re fine with 5,000 IU of both.

jackie September 2, 2010 at 3:07 pm

Awesome! Thanks for your reply! Would the fermented cod liver oil replace the Krill Oil? And, if I switched to that could I still take my multi-vitamin? The multi-vitamin is a whole food one.

Chris Kresser September 2, 2010 at 3:14 pm

Yes, it would replace the krill oil.  I’m not big on multivitamins.  Read why.

jackie September 3, 2010 at 7:27 am

Great, thanks again for the information!! :)

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