Table of Contents
What Are the Benefits? | What Does It Do? | Foods High in Vitamin K2
The role K2 plays is still not entirely understood, but research suggests that a nutrient deficiency of this vitamin can have far-reaching consequences for your health.
A study published by the European Prospective Investigation into Cancer and Nutrition (EPIC) revealed that increased intake of vitamin K2 may reduce the risk of prostate cancer by 35 percent. (1) 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 prostate health.
What Are the Benefits?
Unfortunately, many people are not aware of the health benefits of the K2 vitamin. The K vitamins have been underrated and misunderstood up until very recently in both the scientific community and the general public.
Vitamin K2 can help you maintain cardiovascular health, improve your skin, strengthen bones, and promote brain function. Find out more about this powerful nutrient.
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 the K2 vitamin’s role in the body extends far beyond blood clotting. It may help stave off chronic disease by:
- Preventing cardiovascular disease
- Ensuring healthy skin
- Forming strong bones and improving bone health
- Promoting brain function
- Supporting growth and development
- Helping to prevent cancer
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What Does It Do?
The K2 vitamin has so many functions not associated with K1 that many researchers insist that K1 and K2 are best seen as two different vitamins entirely.
Differences between Vitamins K1 and K2
A large epidemiological study from the Netherlands illustrates this point well. Researchers collected data on the vitamin K intakes of the subjects between 1990 and 1993. (2) They measured the extent of heart disease in each subject, who had died from it, and how this related to 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 K2 intakes were:
- 52 percent less likely to develop severe calcification of the arteries
- 41 percent less likely to develop heart disease
- 57 percent less likely to die from it
However, intake of vitamin K1 had no effect on participants’ heart health.
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, like the soft tissues. (3) In an acknowledgment of the different roles played by vitamins K1 and K2, the United States Department of Agriculture (USDA) determined the vitamin K2 contents of foods in the U.S. diet for the first time in 2006. (4)
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Do We Need K2 in Our Diet?
A common misconception is that human beings do not need K2 in their diet, since they have the capacity to convert vitamin K1 to K2. The amount of K1 in typical diets is generally greater than that of 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 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 K2 in the diet is that both epidemiological and intervention studies show its superiority over K1. According to the epidemiological study from the Netherlands referenced above, intake of K2 is inversely associated with heart disease in humans, while intake of K1 is not. A 2007 study showed that K2 is at least three times more effective than vitamin K1 at activating proteins related to skeletal metabolism. (5) And remember that in the study on the K2 vitamin’s role in treating prostate cancer, which I mentioned at the beginning of this article, vitamin K1 had no effect.
Foods High in Vitamin K2
All of this evidence points to the possibility that K2 may be an essential nutrient in the human diet. So where does one find K2 in foods? The following is a list of the foods highest in the vitamin:
- Natto, a soy dish popular in Japan
- Hard cheese
- Soft cheese
- Egg yolks
- Butter
- Chicken liver
- Salami
- Chicken breast
- Ground beef
It was once erroneously believed that intestinal bacteria played a major role in supplying the body with this vitamin. However, the majority of evidence contradicts this view. Most of the K2 produced in the intestine is embedded within bacterial membranes and not available for absorption. Thus, intestinal production of K2 likely makes only a small contribution to vitamin K status. (6)
While some foods like natto and hard cheeses are high in K2, many people don’t consume them regularly. This is where smart supplementation can play a role. When supplementing with K2, consider a product that contains a blend of MK-4 and MK-7 forms, which may have unique benefits.
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Fermented Foods Are a Good Source of K2
Fermented foods, however, such as sauerkraut, cheese, and natto, 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. One study demonstrated that MK-7 increased the percentage of osteocalcin in humans three times more powerfully than did vitamin K1. (7)
Butter and “Activator X”
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. (8) He found that the Activator X concentration varied 50-fold. Animals grazing on vitamin K-rich cereal grasses—especially wheatgrass 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 topsoil that showed 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.
We’re Still Learning about the Health Benefits of K2
New research that 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.
Does anyone know of research that would contraindicate supplementing with large does of K1 (1000mcg)? Some of the convenient supplements that contain mk4 & mk7 also contain K1. I am wondering if it has a negative clotting effect (too much clotting factor).
You can’t take too much vitamin K. Per the FDA there is no upper limit. And too much vitamin K will not interfere with your clotting factor. A deficiency of vitamin K can interfere with clotting, but high levels are not a problem.
What is the best natto starter for making high quality natto?
I understand some companies sell low quality starter like cultures for health and body ecology for example both sell milk kefir grains that stop repopulating where as Kefir Lady and other providers sell high quality kefir grains that last indefinitely and just keep repopulating as long as their fed, so is there natto starters that last indefinitely?
Hi Mary Jo,
I hope you see this message!
I’m glad to hear Your out of the Osteoporosis range. Yay.
While I’m eating I take about 5 to 6 drops of K2 MK-4 twice aday..You need to take a little healthy Fat with it..Organic coconut oil is a good choice, but healthy fat could be in the food your eating when you take it.
Not sure how many drops your taking, but you do not have to over do Mk-4..I know of some people that just take a couple to 3 drops,and there teeth feel smoother.
Do your teeth feel Smoother? as most peoples do when they take MK-4. .
D3 works better without fat.
There is a great group of people on Inspire.com that have Osteo, and there is some Awesome information there..Just hunt around on that website about k2 MK-4.
Hi Annie,
Thanks for the info. I am actually taking one pill that is 15000 mcg dosage. I take it in the morning with my other vitamins. I have not noticed anything with my teeth. I am concerned that it is too much.
Dr.Mercola advises against the intake of vitamin K2 when one is on blood thinners. Does that also hold for clopidogrel (sold in Australia under the name Plavix)?
I’ve been taking double dose, any possible negative side effects? I take http://pronordick2.com
Chris,
I would like to answer Mary Jo’s question about K2-MK4, but cannot find her post!
Sorry to say this, but this is a mess lol.. But what type of order do you have these in?
As there not by Date etc.!!!
Take Care,
Annie.
Hi Annie,
I understand that you tried to reply to my post regarding my dosage of 15,000 of MK-4 but were unable to.
In the meantime I had a follow up dexascan and the results show that I improved from osteoporosis to osteopenia. I am not sure if the K2 was the factor or not. My doctor still insists that this dosage is way too high.
I would still value your input.
Thank you
Mary Jo,
Glad to hear your Dexa came out so good.
Are you really taking, 15,000 mg of K2- MK-4? Way too HIGH..
I think you mean, 5 mg. or 15mg ??
Is there a test i can do to test for levels k2 in milk. I want to compare nit dont know how to test it?
You’ve listed salami as a food rich in K2. It would’ve been more informative if you’d mentioned that salami – and a lot of processed meats – also contains high levels of sodium chloride, sodium nitrate, sodium nitrite and sodium erythorbate.
Processed meats can contribute to pancreatic cancer. My father manufactured processed meats in his business and died of pancreatic cancer. This type of cancer doesn’t show up until it’s too late, with an 85% mortality rate, and you generally only get “6 weeks” after diagnosis.
I’ll look for K2 in alternate sources. Thanks for the article, very informative, other than this omission.
Geez!!! stop worrying about your prostate!!!
just drink water, eat LOTS and LOTS of fruit,, and LOTS and LOTS of green leaf vegetables and herbs (including lettuce).
Avoid junk, bread, candy, soda, pasta and other junk things and you wont need to worry about anything!!!
Cheese is shocking for you!!! but in small amounts its not a problem if you are eating fruit and vegetables and water.
if you can ‘tip’ the balance on your scales of healthy Vs junk food, then you wont need to worry!!!
also: you answered your own question in this article!! you said that cattle that eat alfalfa and wheatgrass will have more K2 because of the vitamin K in what they are eating!!! so??
go ahead and eat wheatgrass and alfalfa!!!
also: KALE and basil and a whole host of other green leaf plants are full of K2 !!!
not as much as Natto,, but really, so what, Lol !!
just eat healthy and you wont need to worry about yours or anyones prostate 😉
“Cheese is shocking for you!!!”… and where did you get this idea? Care to post some evidence to back up this OPINION? Study results?
Brad,
About “cheese is shocking for you…”
You could try to read the book “The China Study”
The fats and proteins in dairy are like those in flesh but in a liquid and more digestible manner. This is good and bad but after being converted into cheese, it becomes more difficult to digest.
Eating food that taxes the digestion system is not wise… on the other hand, eating fresh fruit and vegetables with their enzymes intact can be processed and assimilated by the body much easier…
the most important; ”stop worrying”!!!
I was wondering about the use of K2 if you are taking nattokinase for a blood thinner. My husband has A-Flutter and is on Diltiazem, a calcium channel blocker. He didn’t want to go on Warfarin. He is taking a few supplements and I’ve read that you need a good amount of K2 if you are supplementing others such as magnesium, D3, etc. But wouldn’t the K2 be counter productive if you are trying to keep the blood thin? When he was on Warfarin he was told he couldn’t eat the veggies and oils high in Vit. K. Thanks for any input.
Read the other comments especially by Chris. This has already been answered more than a few times.
Natto is delicious when mixed with spaghetti, olive oil, garlic and chili. It gives the dish a cheesy taste.
Hello,
When you refer to K2, your not saying which K2!!
There is K2 MK-4, and there is K2 MK-7..
There both a bit different..
Just want to mention , that we get plenty of K1, by just eating Greens..
K1 has been to known to give a few people Leg Cramps, but that will not happen with the K2’s.
K2- Mk-4 takes the calcium to your Bones and Not Your Arteries -Soft tissue .
K2 MK4 has a short shelve life in the body. about 4 hours.
You need to take it about 3 times a day while eating, and with some healthy fat. Olive oil, Avocado’s, Organic Coconut oil, Organic pastured Butter etc. . Not processed oils, or fats.
When talking about meat. Its Organic Pasture meat.
You also need to take D3 once a day with it also.Some Drs. recommend 5000iu D3 aday. That said, get it checked by your Dr. to know how low or high your D3 is.
K2 Mk-7 has a longer shelve life in the body.
About 3 days.
Some people that take K2 Mk-7 will get heart palpitations,and have a problem falling asleep.
If you do take it. Start off SLOW, and do not take it before bed.
There are cheese’s that have k2 MK-4.
But not all hard cheese have it etc.…
Aged Gouda is one of them to take, but you have to eat allot.
Natta has both types, but most people have a hard time eating it, as it slimy for some, and stinky.
You can find at most Asian markets.
Amazon sells K2 MK-4 which is made by Throne. It is pricey, but lasts a long time.
I do NOT have anything to do with Amazon or Thorne vitamins..
I hope this all makes some sense!!
There are some good books out there about K2 etc..
One is:
“Vitamin K2 and the Calcium Paradox: How a Little-Known Vitamin Could Save Your Life” By Kate Rheaume-Bleue.
I have nothing to do with this book.
I have Osteoporosis, and need to be Very Pro-Active about my Bones, Health..
Hi Annie, thanks for your reply. I still have a problem regarding vitamin K1 and leafy greens as i still don’t see how our ancestors could have accessed the K1 without cooking the greens because of the cellulose problem? and where did our ancestors get leafy greens during ice ages which lasted for thousands of years at a time? This got me thinking as to whether or not parts of the animal we no longer find palatable may have been a good source? considering the K vitamins are fat soluble i can’t see how leafy green vegetables could be the best source? I have also read all gouda cheese is a good source of K1 because of the bacteria used in the fermentation process? The internet seems to offer conflicting advice on the subject! I do not eat leafy greens and my blood clots fine so maybe i am worrying about nothing, but i am interested in the K vitamins after reading about K2 and the ‘green leafy veg best source’ bit got me thinking you know?
Thanks again though,
Mark.
Hi Mark,
I have no idea how our ancestors ate Greens!
Are you talking about the Paleo Diet?
I do know when I grow my Organic greens , I get Leg cramps from it, when I eat a big salad.
This also just made me wonder how long our Organic Greens for salad sit on the shelves in the Market, or by the time we buy our Market greens, how long after there picked, and on the shelves to we get to buy it!
(I live in California)
Someone , on another website about Osteoporosis described in chemical terms why leg cramps happen from Greens ..Right now I would have to do allot of searching to find it..I do not have the time.
Take Care,
Annie
Hi Annie,
Thanks for all of the information in a very easy to understand way. I too have osteoporosis and have been trying to be proactive with my care. I started taking K2 Menatetrenone which I believe is MK4 (15,000 mcg). When my doctor saw the dosage she immediately suggested I cut back for fear of blood clots. In your research have you found what dosage is safe?
Thanks
I was responding to your comment on January 12, 2014. Hope that helps so I can get your input.
Thanks
Hello Mr. Kresser.. I have been reading a lot recently about vitamin K, especially K1 and K2 and have read your articles on the subject. I am eating gouda cheese for my K2 requirements, but i am a little confused regarding vitamin K1. It seems the best sources are leafy green vegetables? Now i thought humans could not digest cellulose, so how would we have obtained vitamin K1 from raw leafy green veg without cooking it to break the cellulose down? We did not evolve eating cooked foods, and throughout ice ages there were very few green leafy vegetables to be eaten and the Inuit don’t consume these foods regularly either, so i wonder if human beings can synthesize K1 in the body naturally? I just don’t see how we could have obtained it through raw green veg during evolution and ice ages?
Thanks for any input,
Mark.
You talked about fermented food as good source of k2. Can you please talk about indian fermented foods like idali dosa curd etc?
Hi Chris,
Would Kombuchia have k2.
Kind regards
Rosalyn
I’m taking 4 mg warfarin qd for chronic afib. I try to avoid food items with vit K but is it ok to take a supplement that contains vit K2?
A Nattokinase product – Nattokinase NSK-SD – (emanating from the Japanese Scientific Laboraory) states it has removed K2 from this Natto extract to accommodate people who are on Warfarin: they say while natto dissolves Fibrin in the blood & so thins it & warfarin also thins the blood – I don’t know by what mechanism, K2 does the opposite & is a clotting agent – hence they would be working against each other.
My question is, which is better for a person with elevated BP, K2 or this nattokinase? Can you elucidate?
Thanks.
My wife is taking both nattokinase and K2. It it possible to get nattokinase with the k2 still in it such as in a product called Nattovena.
Hey Chris,
I have been looking at the relationship between K2, D3, Calcium, and Magnesium. I was going to purchase Green Pastures Skate/Grass Fed Butter oil, Krill Oil, or Cod Liver Oil. There is a lot of information to read and understand – I think I am a little lost!
Would I be better off with A combination of Natto, pasteured egg yolks, and a D3 supplement rather than the Skate/butter Oil?
Or what would you recommend combo wise or product? I have to make sure I get enough D,K2, Calcium, and Magnesium because of some health battles.
Thank you.
Dear Chris-thank you for sharing so much informative information. No one here asked about supplementing with ‘Natural Vitality Calm with Calcium’, and I have been taking it nightly for about 2 years. Now I am paranoid… It also contains Vitamin C as Ascorbic acid, D3 from cholecalciferol, Calcium from calcium gluconate, Magnesium from magnesium citrate, Potassium from potassium citrate, and Boron from boron citrate.
I mostly take it to supplement, but also because it really helps me to have a bowel movement in the morning.
Thanks, in advance
All this talk but few testimonials! Is the positive effect of vitamin k2 going to need 20 years of study and a team of 40 statisticians to detect an otherwise inmeasurable positive effect?