Vitamin K2 is a fat-soluble vitamin that most people don’t know much about. But what they don’t know may be indirectly hurting them.
Because vitamin K2 has important health benefits. In fact, in order to be considered a vitamin, a nutrient must be shown to be essential for health.
Vitamin K2 meets that criteria. It is essential for health.
If you’ve read my book, How to Heal Cavities and Reverse Gum Disease (formerly called How I Healed My Teeth by Eating Sugar), you probably know that vitamin K2 is important for teeth and bones. It helps to move minerals like calcium into teeth and bone.
But it also is important for other aspects of health, including cardiovascular health. And in this post I intend to provide some evidence for that benefit plus some suggestions for how to obtain vitamin K2 from natural foods.
What Is Vitamin K2?
This first section is a little bit sciency. Not too much. But a little. If you prefer, you can skip to the next section and get to the details about how vitamin K2 (also called menaquinone) supports heart health.
Vitamin K2, also known as menaquinone, is actually a group of related compounds. Each is structurally similar, but they have different lengths to their “tails”.
The “tails” are composed of 4, 5, 6, 7, 8, 9, 10, 11, 12, or 13 isoprenoid groups. Don’t worry about what that means. But I’m just explaining this much to help explain what the differences between the different menaquinones (vitamins K2) are.
The menaquinones are called menaquinone-4, menaquinone-5, menaquinone-6, etc. based on the length of their “tails”.
Each of these menaquinones behaves a little differently. So it is a mistake to view them as all being interchangeable. And of these, only a few (mostly menaquinone-4 and menaquinone-7) have been studied in much detail regarding their health effects.
However, as a group, research shows that menaquinone intake (including all different types in different amounts from food sources) is associated with better heart health. So for the purposes of this post, I won’t differentiate too much between the different menaquinones.
Note that vitamins K2 and K1 are different enough that they are not interchangeable in terms of heart health. Research has shown that only K2 intake is associated with heart health. K1 intake does not correlate to heart health.
Vitamin K2 is thought to be produced by some animals and bacteria from vitamin K1. So for some animals, eating large amounts of vitamin K1 (from green plants) can lead to heart health indirectly through production of K2. However, in humans conversion of K1 to K2 is thought to be non-existent or so low that K1 intake does not produce sufficient K2 to produce any benefits.
How Is Vitamin K2 Protective of Heart Health?
Research shows that vitamin K2 (menaquinone) intake from food is positively correlated with heart health (or inversely correlated with heart disease and mortality).
In other words, the more K2 that a person eats regularly from food, the lower the risk of heart disease or heart disease events.
One such study is the Rotterdam Study.  In this study researchers reported that high K2 intake is associated with (among other things), saturated fat intake, dietary calcium, and low polyunsaturated fat intake.
The researchers write that “intake of menaquinone (mainly MK-4 from eggs and meat, and MK-8 and MK-9 from cheese) is not related to a healthy lifestyle or diet, which makes it unlikely that the observed reduction in coronary risk is due to confounding”.
In other words, the researchers believe that a diet that includes eggs, meat, and cheese is associated with poor health. And yet, despite this fact (in their minds), the high intake of vitamin K2 is clearly associated with low risk of cardiovascular disease.
So this presents somewhat of a conundrum for the researchers because meanwhile, they found that high intake of vitamin K1 (which is associated with a “healthy” lifestyle that includes a lot of vegetables) is not linked to improved heart health after factoring for increased fiber intake. (Fiber intake is an independent factor that reduces cardiovascular risk.)
(It is worth noting that some research suggests that vitamin K1 intake is associated with reduced risk of cardiovascular disease. However, that research doesn’t make it clear whether it took into consideration fiber intake. )
So how is it that vitamin K2 (menaquinone) could have protective effects in the cardiovascular system?
Well, I’m sure that, as in everything, there are a lot of complexities that cannot be reduced to simple formulas. But one plausible explanation for how vitamin K2 could exert a protective effect is through moving minerals into teeth and bones and out of soft tissues and blood vessels.
One aspect of cardiovascular disease can be the calcification of arteries. And a deficiency of vitamin K2 could help to explain calcification of arteries.
There’s a group of proteins called vitamin K-dependent proteins (VKDP). One such protein is called MatrixGla Protein (MGP).
MGP has been shown to play a role in keeping calcium out of soft tissues and blood vessels. As a VKDP, MGP requires vitamin K2 in order to activate. 
In other words, without sufficient vitamin K2, MGP will not be able to move calcium out of the blood vessels and into bone and teeth.
As a result, arteries are more likely to become calcified.
Obviously, heart disease has a lot of other factors at play. For example chronic inflammation is thought to play a major role in the development of heart disease.
But a vitamin K2 deficiency seems to be another important factor.
Getting Vitamin K2 from Food
If you’ve read much of my writing, you know that I’m not a huge fan of reductionism or “magic bullet” thinking.
I believe that the best way to get good nutrition is through a variety of foods, which can include plenty of the things that many groups seek to demonize, including sugar, wheat, dairy, meat, vegetables, fruit, grains, beans, etc.
And here again, that is kind of the point. By excluding foods, we can do harm to ourselves.
Just as fruit and vegetables provide fiber, vitamins, minerals, polyphenols, etc. that contribute to our health and sugar provides…uh…sugar, which is a nutrient and beans provide starch and fiber and potassium…
Many foods that many of us have excluded either by choice or because of their limited availability turn out to have important health benefits by providing, among other things, vitamin K2.
Of foods that are commonly available, those highest in vitamin K2 include egg yolks, cheese, poultry (especially poultry liver), and butter.
The levels are typically higher in foods coming from animals with free access to fresh, green plants to eat. The reason is that when animals can efficiently convert vitamin K1 (from green plants) into K2, the K2 content of those animals and their milk will be higher.
Before we go any further, let’s talk about how much vitamin K2 you might want to eat daily to get the heart benefits.
According to the U.S. Food and Nutrition Board (FNB), the minimum recommended daily intake of all vitamin K (both K1 and K2) is 120 mcg for men and 90 mcg for women.
Those values are pretty low. And I suspect that if somebody did a study of traditional diets of cultures in which heart disease is virtually unknown, they’d find that the average daily intake of vitamin K2 is higher than the recommended total vitamin K intake from the FNB.
Still, in the Rotterdam Study, even 40 mcg of daily vitamin K2 intake is associated with significant heart health improvements over lower amounts of vitamin K2 intake.
Personally, I’d want to eat 100 mcg or even 200 mcg or more per day from food whenever possible. I wouldn’t be rigid about it. But I think there are enough benefits from adequate K2 that I am cognizant of what foods contain K2 in substantial amounts, and I give preference to eat more of those things that I like. I don’t force anything. I just am aware.
Let’s look at the amounts of K2 found in the foods I mentioned earlier plus a few more good sources.
- egg yolks – 1 egg yolk contains approximately 6 mcg of vitamin K2
- butter – 1 stick contains approximately 20 mcg of vitamin K2 (Kerry Gold tested much lower, however.)
- cheddar cheese – 100 g contains approximately 21 mcg of vitamin K2
- Jarlsberg cheese – 100 g contains approximately 76 mcg of vitamin K2
- chicken leg and thigh (dark meat) – 100 g contains approximately 60 mcg of vitamin K2
- chicken liver – 100 g contains approximately 12 mcg of vitamin K2
- chicken heart – 100 g contains approximately 14 mcg of vitamin K2
- pork sausage – 100 g contains approximately 380 mcg of vitamin K2
- pork chop with bone – 100 g contains approximately 75 mcg of vitamin K2
Clearly, based on these values, the best way to eat significant amounts of vitamin K2 from food is to eat Jarlsberg cheese, the dark meat from chicken (chicken breast is relatively low in K2), and full-fat pork.
(Although pork is very high in vitamin K2, and it very well may contribute to heart health, it is worth noting that much of the vitamin K2 in pork is from long-chain menaquinones that haven’t been studied as well as, for example, menaquinone-4, which is found in chicken.)
In fact, despite the fact that at one time I rather simple-mindedly and zealously cautioned against eating too much poultry because of the polyunsaturated fat content, I have since realized that was wrong.
As I have written about in the updated edition of How to Heal Cavities and Reverse Gum Disease, I no longer believe that all polyunsaturated fat is created equal – even omega-6 fatty acids.
In honestly believe that you have to look at the whole food. Traditional Chinese Medicine holds poultry and pork in high esteem, for example. Poulty and pork is relatively high in omega-6 fatty acids. Yet they are both good sources of vitamin K2. Could this be purely coincidence? Sure. Then again, it might be that the K2 in poulty and pork is part of the therapeutic value the Chinese medicine practitioners have long valued.
I also suspect that kidneys are generally a good source of vitamin K2, but I cannot find much research showing this to be true across species. As I wrote about in an article I posted on my Naturally Reverse Dental Decay site, studies in rats and humans have shown that brains and kidneys contain large amounts of vitamin K2. So it seems likely that this is true of other species as well.
In any case, I do sometimes eat kidneys as they are available for purchase and because I raise some of my own animals for meat.
I am cautious about eating brain. Although it is quite delicious and highly nutritious, I am a little scared of the various prion diseases that can affect animals and their transference to humans. So despite the fact that brain is very likely a rich source of vitamin K2, I don’t eat it presently.
I have a hard time finding high quality pork. So I don’t eat much pork – though I am considering raising (small) pigs in the future.
So at this time, my primary sources of K2 are chicken (including dark meat, livers, and hearts), kidneys (possible source), cheese (I just eat regular cheddar cheese most of the time), eggs, and butter.
As a final note, some people may wonder if so-called high vitamin butter oil is a good source of vitamin K2.
It is…sort of…maybe.
High vitamin butter oil is what Weston Price originally recommended as a good source of vitamin K2. It is produced from the milk of animals grazing on fast-growing spring grass. So it does, in fact, produce much higher levels of vitamin K2.
According to some research, the high vitamin butter oil sold by Green Pasture contains over 80 mcg per 100 g.
That is about four times what is contained in regular butter.
But here’s the catch: high vitamin butter oil sells for about $60 for 8 ounces, which mean you’re getting somewhere in the range of 200 mcg of vitamin K2 per bottle.
That means you’re paying $0.30 per microgram, if I’ve done the math correctly.
On the other hand, Organic Valley butter sells for $6 a pound at my local co-op. And there is somewhere in the range of 80 mcg of vitamin K2 in that.
Which means I’m paying around $0.08 per microgram of vitamin K2 when buying the Organic Valley butter.
It’s possible that the green label Organic Valley butter that is produced from May-September is even higher in vitamin K2. I haven’t seen a test for that one, specifically.
Anyway, I highly suspect that high vitamin butter oil isn’t an economical source of vitamin K2. But time could prove me wrong.
I know I said that would be the last thing. But, I will also mention that if you’re interested in supplemental vitamin K2, I cannot tell you for certain that you can expect the same benefits as getting it from food. But it is possible.
Personally, I wouldn’t rely on supplemental K2 as a complete substitute for food-based vitamin K2. But it might provide some benefits. Certainly, there is research showing that supplemental K2 can be beneficial in some conditions such as osteoporosis.
I am not sure about the safety of any supplemental K2 long term. But I will say this: menaquinone-4 supplementation even in very large amounts has been shown to have no toxicity in medium term human research. Meanwhile, there are lots of reports online of people experiencing headaches, high blood pressure, and anxiety when supplementing with the MK-7 form.
So personally, when I take supplemental vitamin K2, I take the MK-4 form only. I am not saying you should do the same or that you should take any supplemental vitamin K2. But if you do, take my opinion with a grain of salt.
Should you decide you want to supplement with vitamin K2, here are some of the products on the market that I have either used myself or that appear to be good. (Note that these are Amazon associate links.)
- AOR MK-4 15 mg (this is a high-dose product)
- Relentless Improvement MK-4 15 mg (also a high-dose product)
- Thorne liquid MK-4 (this is more economical than the others if you take, for example, 1000 mcg per day)
As always, if you have questions or comments, please post below.
Oh, and ONE more last thing: if you are looking for a good resource to find vitamin K2 sources of food, Chris Masterjohn has a calculator available HERE (scroll down to find it).