What Is Vitamin K Good For? 14 Benefits, K1 vs K2, Sources, Deficiency
If I asked you to name a vitamin which is important in the human body, what vitamin would you name?
Most people would probably answer "vitamin C," or maybe "vitamin A," or "vitamin E." Perhaps you would mention B-complex vitamins.
One nutrient you probably wouldn’t think of mentioning is vitamin K.
A lot of people are scarcely aware that vitamin K exists - or have no idea it exists at all.
But vitamin K is not just important; it is essential.
In this article, I am going to tell you all about vitamin K - what it is, what it is used for in your body, and its health benefits.
I will also tell you how much vitamin K you need and where you can get it.
Let’s get started!
What is Vitamin K?
Like vitamin B, vitamin K is actually a group of nutrients which share structural similarities.
K vitamins are fat-soluble and are required by your body for a couple of key purposes:
- Coagulation of your blood
- Calcium binding within bones and as well as other types of tissue
If you are curious why it is called vitamin K, it is pretty easy to remember that the "K" stands for "koagulation."
That is simply the Danish spelling of "coagulation."
Interestingly enough, scientists were unaware of the existence of vitamin K for a very long time.
It wasn’t until the 1920s and 30s that vitamin K was discovered, quite by accident.
Animals that were being fed diets that were highly restrictive were suddenly experiencing uncontrolled bleeding.
This was because they were not getting enough vitamin K (1).
KEY POINT: Vitamin K actually refers to a group of fat-soluble vitamins which your body uses for calcium binding and coagulation.
Vitamin K1 vs. Vitamin K2
The next thing you need to know about vitamin K is that there are two main types used by your body.
These are known as vitamin K1 and vitamin K2.
Vitamin K1 is sometimes known as "phylloquinone."
The vast majority of the vitamin K that you consume takes the form of vitamin K1.
It accounts for around 75-90% of all the K vitamins that you eat (2).
Vitamin K2 on the other hand is not nearly as common. You may eat it sometimes in animal products or foods which have been fermented.
Interestingly enough, your body also produces it, courtesy of the healthy bacteria which live in your digestive tract.
There are actually a few different subcategories of vitamin K2. They are known as "menaquinones," which is abbreviated as "MKs.”
Each has a number attached to the end which signifies how long their side chains are. At the lower end is MK-4, and at the upper end is MK-15.
KEY POINT: The two main types of K vitamins are denoted as vitamin K1 and vitamin K2.
Vitamin K1 makes up around 75-90% of the vitamin K in your diet, while vitamin K2 is the second most abundant form.
What Food Sources Contain Vitamin K1?
If you want to increase your intake of vitamin K1, you can get it from any of the following foods in abundance (3):
- Kale: 1,062 mcg
- Collard greens: 1,059 mcg
- Spinach: 889 mcg
- Turnip greens: 529 mcg
- Broccoli: 220 mcg
- Brussels sprouts: 218 mcg
Notice that many of these are leafy green vegetables. These foods are incredibly nutritious for you all around.
They are rich not just in vitamin K1, but in many other vitamins and minerals which your body needs for optimum health.
Most people can use more of them in their diets, so food sources are a great way to get more vitamin K1.
KEY POINT: Leafy green vegetables are an excellent source of vitamin K1, and are very nutritious in general.
Increase your intake of them if you want to boost your vitamin K1 levels.
What Food Sources Contain Vitamin K2?
As just discussed, vitamin K2 actually comes in a number of different subtypes.
Some subtypes can be manufactured by bacteria while others cannot.
The MK-4 subtype is an example of a form of vitamin K2 which bacteria do not create.
You can however get MK-4 through chicken, butter, and egg yolks.
Bacteria do produce subtypes MK-5 through MK-15. That means that they are common in foods which are fermented.
If you are looking to get more MK-8 and MK-9, you can do so by increasing your consumption of cheeses.
- Natto: 1,062 mcg
- Pork sausage: 383 mcg
- Hard cheeses: 76 mcg
- Pork chop (with bone): 75 mcg
- Chicken (leg/thigh): 60 mcg
- Soft cheeses: 57 mcg
- Egg yolk: 32 mcg
Some other foods which are high in vitamin K include carrot juice, pumpkin, pomegranate juice, okra, pine nuts, blueberries, Caesar salad dressing, chicken breast, iceberg lettuce, grapes, vegetable juice, cashews, and raw carrots.
KEY POINT: You need to eat a variety of foods to get vitamin K2, because the different subtypes are found in different foods.
Animal products, fermented foods, and cheeses are good choices.
Vitamin K1 vs. Vitamin K2: They Behave Differently in the Body
Both vitamin K1 and vitamin K2 are the same in terms of the role they play. Both assist with blood clotting and calcium binding.
But there are differences in how we absorb the two.
We only actually absorb around 10% of the vitamin K1 that we get from vegetables (7).
On the other hand, we seem to do a pretty good job absorbing vitamin K2 (8).
This in part has less to do with the nature of vitamin K1 versus vitamin K2, and more to do with the types of food that we find them in.
You will recall that vitamin K is fat-soluble.
That means that our bodies can absorb it more easily when fat is present.
Now think back to the lists of foods which contain vitamin K1 and vitamin K2.
The vitamin K1 foods are vegetables.
The vitamin K2 foods on the other hand are largely animal products which are higher in fat.
There is however one key structural difference which may also make a difference in absorption.
The side chains of vitamin K2 are longer than that of vitamin K1.
This makes a difference in how long vitamin K can circulate in your bloodstream.
Vitamin K2’s structure allows it to stay in your bloodstream significantly longer than vitamin K1.
In fact, vitamin K2 is able to circulate in your blood for days on end, whereas vitamin K1 can only stay in your blood for a few hours (9).
Because vitamin K1 does not remain in your blood for as long, it may be absorbed by fewer tissues.
Indeed, it seems that most of it goes to your liver (10).
Vitamin K2 on the other hand is able to reach more body tissues.
KEY POINT: Our bodies seem to have a much easier time absorbing vitamin K2 than vitamin K1.
This reflects both structural differences between the two (vitamin K2 circulates much longer in the blood) as well as differences in the types of foods which vitamins K1 and K2 are found in (vitamin K2 is present in a lot of high-fat foods, which aids in absorption).
How Much Vitamin K Do You Need?
These are the recommended amounts of vitamin K for different age groups (11):
Birth to 6 months
The requirements for pregnant and lactating women are the same.
KEY POINT: For adult men, the recommended daily amount of vitamin K is 120 mcg.
For adult women, the recommended daily intake is 90 mcg.
How Common is Vitamin K Deficiency?
On the whole, it is quite rare for people to develop vitamin K deficiency.
There are a few groups however which are at a heightened risk:
- Newborn babies who did not receive vitamin K treatments when they were born. These treatments are important, because vitamin K does not transfer adequately via the placenta. Symptoms of deficiency generally show up within the first few weeks after the child’s birth in the form of vitamin K deficiency bleeding, often abbreviated as VKDB. When VKDB presents later (within 2-12 weeks of birth), it may also point toward malabsorption issues, or a low amount of vitamin K in breast milk.
- People who have a hard time absorbing vitamin K. At any age, it is possible to have low vitamin K levels if your body is inefficient with absorbing it. This may happen as a result of a specific malabsorption disorder, or it may manifest as a complication of celiac disease, short bowel syndrome, cystic fibrosis, or ulcerative colitis. It can show up with other gastrointestinal conditions as well.
- People who have had bariatric surgery. Sometimes this can occur without obvious clinical symptoms.
- People taking certain medications. I will get into this in depth in just a little bit.
If you do have a difficult time absorbing vitamin K, supplementing with it may be necessary.
You also may need to have your vitamin K levels checked on a regular basis in order to make sure that you are staying healthy.
KEY POINT: Vitamin K deficiency is relatively rare in the general population.
It can however occur in infants if they do not receive the vitamin K they need through supplementation at birth and/or diet in the weeks that follow.
It is also possible to be lacking in vitamin K if you have trouble absorbing it. If you are on certain medications, you also may require vitamin K supplements.
Can You Get Too Much Vitamin K?
If you are thinking about supplementing with vitamin K, you now know how much is recommended each day.
But is there an upper limit?
Are there health risks associated with taking too much vitamin K?
There is no formal upper limit for vitamin K at all (11).
The reason is that the Food and Nutrition Board has established no cause for concern.
Indeed, the board states, "no adverse effects associated with vitamin K consumption from food or supplements have been reported in humans or animals."
That means that you can feel safe taking vitamin K supplements, and you do not need to worry about taking too much.
So long as your dosage is not overly excessive, you should be fine. Just aim to get your levels back where they need to be.
KEY POINT: There is no formal upper limit for vitamin K, because its toxicity potential is so low.
The FNB has found no signs that taking vitamin K in supplement form or absorbing it through food is dangerous on its own (interactions are a different story - see below).
Are There Medications Which Interact With Vitamin K?
There are a few different medications which can interact adversely with vitamin K.
Be mindful of taking vitamin K if you are using any of the following:
Anticoagulants such as Warfarin.
These drugs are most commonly prescribed to patients in Europe. They directly interact with vitamin K, reducing its activity level.
This is by design; it is done to slow the formation of blood clots (12).
You must make sure that you are getting a proper and steady supply of vitamin K while taking this type of medication.
If you abruptly decrease your vitamin K intake, this may lead to an unwelcome increase in the medication’s effects.
If you abruptly increase your vitamin K intake, then the medication may lose some of its effectiveness.
You should talk with your doctor to make sure that you are getting the right amount of vitamin K.
If you are on antibiotics for more than a few weeks, there is a chance that your regimen will result in a decrease in the amount of bacteria in your digestive tract which produces vitamin K.
This means you may need to take a vitamin K supplement temporarily, especially if your diet is low in vitamin K.
Bile acid sequestrants.
These drugs work to keep cholesterol levels down.
One of the side effects is that they can make it harder for your body to absorb fat-soluble vitamins such as vitamin K.
If you are on one of these medications for an extended time period, you may need to take vitamin K supplements.
This is a medication you can take to help you lose weight.
Because it interferes with your body’s absorption of fat, it also may decrease your ability to absorb fat-soluble nutrients.
Usually this does not happen to a problematic degree, but you still may end up needing to take vitamin K supplements.
KEY POINT: There are a few different medications which can interfere with vitamin K.
If you are taking any of the medications listed above, make sure you understand what the impact may be on your vitamin K levels.
Supplement (or not) as needed to make sure that your levels remain healthy.
14 Health Benefits of Vitamin K
Now you know a lot more about vitamin K including its different forms, issues involving absorption, how much you need, and what foods contain it.
But what can vitamin K actually do for your health? Let’s check out the benefits now.
1. Improve the health of your bones.
You probably are aware that calcium is one of the most important nutrients for bone health.
Bones cannot make use of calcium however without a binding agent called "osteocalcin" (13).
Osteocalcin in turn requires vitamin K2 in order to be activated. That means that vitamin K2 is also a requirement for healthy bones (14).
Also of interest is a study which was conducted on postmenopausal women (15).
It was found that vitamin K2 helps to prevent bone fractures.
Another study (16) found that the reduction is fractures through the use of vitamin K2 can be as high as 80%.
It should also be noted that calcium which fails to bind to bones can end up building up inside your arteries.
This can lead to cardiovascular disease.
So vitamin K2 helps to protect bone and cardiovascular health through its action on osteocalcin.
KEY POINT: Vitamin K2 is necessary in order for osteocalcin to bind calcium to bones.
Vitamin K2 supplementation can therefore help to protect the health of your bones, preventing fractures.
It also can prevent calcium from building up in your arteries, preventing cardiovascular disease.
2. Reduce your risk of heart disease.
As just mentioned, vitamin K2 can prevent the build-up of calcium in your arteries.
This in return can lead to a reduction of up to 9% in your risk of heart disease (17).
Furthermore, it has been found that taking medications which block the action of vitamin K can lead to faster calcium build-up (18).
Taking high amounts of vitamin K2 can reduce your chances of fatality by heart disease by as much as 57% (19).
In another study (20), it was found that vitamin K1 supplementation also can help to prevent cardiovascular disease, this time by slowing the rate of arterial calcification within the heart itself.
Taking supplements may also help to reverse this condition.
KEY POINT: Vitamin K can prevent heart disease in a couple of ways.
Firstly, it helps to prevent the build-up of calcium in the arteries.
Secondly, it can do the same within the heart. This can significantly reduce your chances of dying from heart disease.
3. Strengthen your teeth.
Like your bones, your teeth require calcium in order to be strong. That means that they too require the action of osteocalcin (21).
So if you are not getting enough vitamin K in your diet, this prevents osteocalcin from effectively binding calcium within the teeth.
That means that your teeth may be weak. Weak teeth are more prone to forming cavities, breaking, and so forth.
If your teeth are in a weakened state, you also may have pain in them as well as in your gums.
By getting more vitamin K in your diet, you can provide your body with what it needs to keep your teeth strong.
KEY POINT: Your teeth, like your bones, need calcium to stay strong and healthy.
Vitamin K can help osteocalcin to bind calcium within your teeth, leading to improved dental health.
4. Reduce the amount of inflammation in your body.
This study (22) found that vitamin K is involved with inflammation biomarkers.
It seems likely so far based on the research that the action involves a decrease in the expression of certain genes.
When you do not get enough vitamin K, the genes tied to cytokines increase in their expression, which in turn boosts cytokine levels in your body.
This in turn leads to inflammation as well as bone loss.
One thing which is important to know about this process is that vitamin K2 supplementation can only prevent the increase in cytokine levels, not reduce them once they are heightened (23).
For that reason, you should take vitamin K as a preventative measure.
It will not necessarily work as well as a treatment for elevated inflammation.
There are other mechanisms however through which vitamin K also reduces inflammation, like reducing calcification.
So it is best to try and up your vitamin K intake before inflammation sets in - but taking it once you have problems with inflammation can still be helpful.
KEY POINT: Vitamin K has been shown to have an anti-inflammatory effect.
It is believed that this likely is a result of its impact on gene expression for cytokines.
5. Combat autoimmune diseases.
Research has shown that vitamin K may be helpful in counteracting autoimmune disorders.
In one animal study (24), rats were afflicted with experimental autoimmune encephalomyelitis (EAE), which is an animal disease that corresponds with multiple sclerosis (MS).
The study results were promising, and the researchers indicated that vitamin K2 might be a useful and well-tolerated treatment for human MS patients.
Meanwhile, other research has found that vitamin K2 may also be helpful for patients with arthritis (25).
KEY POINT: Studies have shown that vitamin K could have benefits for patients who suffer from a variety of autoimmune conditions.
6. Fight against a number of different forms of cancer.
Quite a few studies have shown that vitamin K is an important nutrient when it comes to combating cancer.
Taking vitamin K2 supplements daily can reduce the risk of developing prostate cancer by as much as 63% (26).
It has been found that liver cancer patients who take vitamin K2 supplements are able to increase their rate of survival.
The vitamin K2 helps to prevent cancer cells from coming back.
The long-term benefits in particular for liver cancer patients appear to be quite promising.
In one study (31), it was found that taking vitamin K2 supplements every day for a period of three years resulted in a significantly lower risk of liver cancer.
Another study (32) found that taking vitamin K can reduce cancer rates overall for a variety of different types of cancer.
This study (33) sheds some light on the mechanism through which vitamin K appears to exert its anti-cancer effects.
It turns out that vitamin K is essential to the role of a gene called Gas6. Gas6 is able to get rid of cancer cells.
If vitamin K is absent, then this gene is not able to do its work.
KEY POINT: Vitamin K has been found to be helpful in combating a number of different types of cancers.
This may be in part the result of the vital support role it plays in conjunction with the Gas6 anti-cancer gene.
7. Vitamin K plays a vital role in nervous and brain function.
You are likely aware that Alzheimer’s is a growing epidemic for which there is no cure. For that reason, prevention is of vital importance.
There is no sure-fire way to prevent Alzheimer’s either, but there are some dietary steps you can take which may help to provide a protective effect.
Researchers who looked at an elderly population found that (34) patients who had early-stage Alzheimer’s disease had "significantly" lower intakes of vitamin K2 than those in the healthy group.
The reason their intake was lower was because they were eating fewer vegetables.
It has also been discovered (35) that vitamin K plays a role in cell signalling as well as the growth of neurons.
This is once again through the mechanism of Gas6.
So if you want to do your part to reduce the likelihood that you will develop Alzheimer’s disease or other forms of cognitive decline, eating more vegetables which are rich in vitamin K is a good idea.
If you decide to take vitamin K supplements for brain health, you should look for it in the MK-4 form.
98% of vitamin K found in the brain is in this form.
KEY POINT: Researchers have found that vitamin K plays a vital role in nervous and brain health, and that low levels of vitamin K may be associated with dementia.
8. With vitamin K, you may be able to reduce menstrual pain.
This study (36) looked into the efficacy of acupuncture injections of vitamin K as a treatment for severe menstrual pain.
The researchers stated that, "Noticeable pain relief was observed 2 minutes after treatment, and subsequent pain reduction occurred at 30 minutes."
The participants in the study were able to spend less time in bed, and required fewer painkillers.
They also reported that their pain was less intense and lasted a briefer period of time, and they were able to participate in more of their daily activities.
The treatment was well-tolerated with no reports of side-effects.
This was a pilot study only, so more research is warranted, but the results are hopeful.
Furthermore, remember that vitamin K is essential for blood clotting.
This means that it may also reduce heavy flow, resulting in lighter periods.
KEY POINT: Women who suffer from severe menstrual pain may want to consider using vitamin K.
Vitamin K acupuncture injections were found to reduce pain and improve quality of life.
9. Improve mitochondrial function.
Vitamin K2 plays a role not unlike that of ubiquinone on a cellular level.
It is able to move electrons, which can increase the function of mitochondria and help generate energy.
Animal studies (37) have indicated that it might even be helpful in dealing with Parkinson’s disease through this mechanism.
Vitamin K2 can even help to protect cultured neurons from glutathione-depleted death (39).
What all of this means in plain English is that you may find that vitamin K2 can improve your energy levels.
So if you are feeling lethargic, it might be a good time to try taking a vitamin K2 supplement.
KEY POINT: Vitamin K2 is able to improve the function of the mitochondria.
10. Improve insulin resistance and treat diabetes.
Those who are looking to reduce their insulin resistance may find that vitamin K2 is a helpful supplement.
The second study linked above however found no improvement for women.
More research is needed to confirm the effectiveness of K2 for lowering insulin resistance in men, and to clarify whether or not it can help do the same for women.
KEY POINT: Insulin resistance in men can be lowered by supplementing with K2. It is unclear whether this effect exists for women.
More research is warranted.
11. It is possible that vitamin K2 could help to counteract the actions of statins, warfarin, and vegetable oils.
What do statins, warfarin, and vegetable oils all have in common?
All of them have a tendency to stand in the way of bodily processes which require vitamin K2 in order to work.
Taking vitamin K2 won’t necessarily curb these effects directly since these substances will still exert their influence.
But it may help to give the same processes the statins are interfering with a bit of a boost by providing them with more vitamin K2.
This in turn may help to protect your overall health if you need to take warfarin or statins or use vegetable oil.
KEY POINT: Statins, warfarin and vegetable oil all can interfere with processes which depend on vitamin K2. Taking vitamin K2 supplements might feasibly help to offset these negative effects a bit.
12. Keep blood clotting properly.
If you have never had problems with your blood clotting, you probably have taken it for granted.
But blood clotting is actually pretty complicated. To function properly, it demands all the right ingredients.
12 different proteins are needed for blood to clot.
But four of these proteins are unable to do their job without vitamin K, which is necessary for activating them (63).
Getting adequate vitamin K2 will ensure that all the proteins needed for blood to clot are activated properly.
It also will help to reduce bruising and will speed up wound healing.
KEY POINT: Vitamin K2 is necessary for blood clotting. Getting sufficient vitamin K2 will help ensure that your blood clots quickly and efficiently when needed.
13. Reduce your risk of mortality from a variety of sources.
Previously, I shared this (32) study with you with regards to vitamin K and cancer.
The findings in the study actually went beyond cancer, however.
In all, over 7,000 participants were studied. All of them had a heightened risk for cardiovascular disease.
It was found that those whose diets included vitamin K at the highest levels had a 36% smaller chance of mortality when compared to those who were getting the least amount of vitamin K.
That isn’t just mortality from cardiovascular disease or cancer. It is from all causes.
So if you want to live longer, vitamin K may be able to help you do it.
KEY POINT: Vitamin K has been found to have a strong protective effect against mortality from a range of causes. Consider taking it to increase longevity.
14. Support the function of vitamin D in your body.
You already know a bit about the functions of vitamin K with regards to calcium.
But thing I have not yet explained is how vitamin K works together with vitamin D to ensure that calcium gets to where it needs to go.
That isn’t actually something you want. Your bones need calcium to stay strong. Without it, they deteriorate, often leading to osteoporosis.
That is why it is so important to make sure you are getting enough calcium in the first place.
Where does vitamin K come into things? First of all, you already know that vitamin K helps to bind calcium in bones and teeth.
So both vitamin K and vitamin D are needed together to ensure that calcium is managed properly in your body.
This has led some to wonder whether it is unhealthy to take vitamin D supplements without also taking vitamin K.
To answer this question, we need to consider the matter of vitamin D toxicity.
If vitamin D levels are elevated too much, calcium levels in the blood may also soar. This condition is known as "hypercalcemia" (50).
Hypercalcemia in turn can result in calcium phosphate building up inside the lining of your blood vessels.
This condition is called "blood vessel calcification," or BVC.
Researchers have found that those who have low vitamin K levels are more likely to develop BVC (53).
Animal studies have also showed that it is possible to prevent BVC through supplementing with high doses of vitamin K (54).
Human studies have looked into this as well.
It has been found that it is possible to reduce BVC development by taking 500 mcg of vitamin K1 daily (55).
So if you are getting too much vitamin D, yes, vitamin D can lead to BVC.
But if you take more vitamin K, that can help counteract that effect.
There is also a suggestion that vitamin K could be depleted through vitamin D toxicity, but this remains an unproven theory (62).
All of this does mean that you should make sure that you are not taking huge amounts of vitamin D.
But right now, there is no reason to assume that low doses are problematic.
Either way, it does seem like taking vitamin K in conjunction with vitamin D is a good idea.
If you must take vitamin D in high doses, the vitamin K should help provide some protective effect.
If you are taking vitamin D in lower doses, it may or may not be important to take vitamin K, but it probably won’t hurt.
KEY POINT: Vitamin D and vitamin K work together to help regulate the distribution of calcium in your body.
Research seems to suggest that taking high amounts of vitamin D may result in blood vessel calcification, but taking vitamin K alongside it may help to reduce this unwanted side effect.
Choosing a Vitamin K Supplement
Now you know all about the amazing benefits of vitamin K for your health.
In most cases, you probably can get the vitamin K you need simply through dietary choices, but what if you need more?
In that case, you will need to shop for a supplement.
In many respects, shopping for vitamin K supplements is much like shopping for other types of supplements. You need to consider factors such as:
- Purity (no unnecessary additives).
- Ease of swallowing and digestion.
- Quantity, dosage, and cost.
- Third-party testing and verification.
- Company reputation.
But shopping for vitamin K is a little more complicated in other respects.
You need to shop for both the MK-4 and MK-7 forms of vitamin K, and you even need to pay attention to the shape of the molecules included in the supplements.
Because this is a complicated topic, I have written a whole other article on it.
Please see my Vitamin K Supplement Reviews to learn all about shopping for vitamin K and to see my recommendations for the best vitamin K supplements currently on the market.
Once you have read the Supplement Reviews in detail, you should be confident shopping for the vitamin K you need.
KEY POINT: As with any other supplement, doing your research is important if you want to purchase a product which is safe, pure and effective.
There are some additional complexities involved with the different forms of vitamin K as well.
Please see my detailed review article for more information.
Conclusion: Vitamin K Is a Vital and Overlooked Nutrient
Now you know all about vitamin K.
This is a nutrient which a lot of people are scarcely aware of, yet it plays many vital roles throughout your body, protecting everything from bone health to heart health to brain function.
If you think you may not be getting enough vitamin K, it is a good idea to go and get your levels tested, and to start taking a vitamin K supplement to support your total health.
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