Vitamin K – The Forgotten Vitamin

Very few people know how important vitamin K is for their bodies. Vitamin K not only controls blood clotting, but it also activates bone formation and even protects against cancer. Protect your health with vitamin K.

What is vitamin K?

Like vitamins A, D, and E, vitamin K is a fat-soluble vitamin.

There are two naturally occurring forms of vitamin K: vitamin K1 (phylloquinone) and vitamin K2 (menaquinone). However, vitamin K2 appears to be the more active form of the two.

Vitamin K1 is mainly found in the leaves of various green plants, which we will discuss below. Vitamin K1 can be converted by the organism to the more active vitamin K2.

Vitamin K2, on the other hand, is only found in animal foods and in some fermented plant foods. In the latter, it is formed by the microorganisms present there. Our intestines also have the right intestinal bacteria that can form vitamin K2 – assuming, of course, that the intestinal flora is healthy.

Foods that contain vitamin K2 include raw sauerkraut, butter, egg yolks, liver, some cheeses, and the fermented soy product natto.

Vitamin K regulates blood clotting

Our organism needs a part of vitamin K so that blood coagulation can function. A lack of vitamin K inhibits the vitamin K-dependent coagulation factors and therefore the blood’s ability to clot, which can lead to an increased tendency to bleed. In order to avoid blood clotting disorders, the body should always be supplied with sufficient vitamin K.

It is interesting to know that, conversely, high doses of vitamin K do not lead to increased blood clotting or an increased risk of thrombosis. Our body is able to optimally use the available vitamin K so that blood clotting remains in balance.

Vitamin K against arteriosclerosis

Vitamin K is not only of great importance for blood clotting but also for the prevention and regression of hardening of the arteries, and arteriosclerosis. But how do such life-threatening plaque deposits in our blood vessels come about in the first place?

What Causes Plaque?

As a result of poor nutrition and rising blood pressure, microscopic tears appear on the inner walls of our arteries. Our body naturally tries to repair this damage. But if the body lacks the necessary vital substances (such as vitamin C and vitamin E), it looks for an emergency solution to at least plug the cracks.

Out of necessity, the body uses a certain form of cholesterol – LDL cholesterol – which attracts calcium and other substances from the blood and thus plugs the cracks in the blood vessels. These calcium deposits are called plaque and, if they break off, can lead to a fatal heart attack or stroke.

Vitamin K regulates calcium levels in the blood

Normally, calcium is an important mineral – not only for teeth and bones but for numerous other functions. However, in order to be able to use the calcium in the corresponding organ, it must also be transported reliably to its destination.

Otherwise too much calcium remains in the blood and could be deposited on the vessel walls or in other undesired places, e.g. B. in the kidneys, which could lead to kidney stones.

Vitamin K is responsible for this redistribution: It removes excess calcium from the blood so that it can be used for bone and tooth formation and is not deposited in the blood vessels or in the kidneys. A sufficiently high vitamin K level thus reduces the risk of arteriosclerosis (and thus of course also heart attacks and strokes) and presumably also the risk of kidney stones.

Vitamin K2 prevents deposits in the blood vessels

Several scientific studies support the plaque-reducing properties of vitamin K. A study with 564 participants was published in the journal Atherosclerosis, which showed that a diet rich in vitamin K2 significantly reduces the formation of deadly plaque (deposits in the blood vessels).

The Rotterdam Heart Study also showed during an observation period of ten years that people who ate foods with a high proportion of natural vitamin K2 clearly had fewer calcium deposits in the arteries than others. The study proved that natural vitamin K2 can reduce the risk of developing arteriosclerosis or dying from cardiovascular diseases by 50%.

Vitamin K2 reverses calcification

Another study even showed that vitamin K2 is able to reverse existing calcification. In this study, rats were given warfarin to induce the hardening of the arteries.

Warfarin is a vitamin K antagonist, so it has the opposite effect of vitamin K. It inhibits blood clotting and is part of the so-called anticoagulants, especially in the USA. These drugs are also popularly referred to as “blood thinners”. Its known side effects include both arteriosclerosis and osteoporosis – simply because anticoagulants prevent vitamin K from regulating calcium levels.

In the said study, some of the rats that were now suffering from arteriosclerosis were given food containing vitamin K2, while the other part continued to be fed normal food. In this test, vitamin K2 led to a 50 percent reduction in arterial calcification compared to the control group.

Vitamin K and D against heart disease

The effect of vitamin K in preventing heart disease is closely related to vitamin D. Both nutrients work hand in hand to increase the production of a protein (Matrix GLA protein) that protects blood vessels from calcification. Therefore, it is important to get both vitamins through food, sunlight, or supplements to naturally reduce the risk of heart disease.

Bones need vitamin K

Bones also need vitamin K — along with calcium and vitamin D — to stay healthy and strong. Vitamin K not only provides the bones and teeth with the calcium they need from the blood but also activates a protein that is involved in bone formation. Only under the effect of vitamin K can this protein called osteocalcin bind calcium and build it into the bones.

Vitamin K2 against osteoporosis

A study from 2005 dealt extensively with vitamin K2 in relation to bone formation. The researchers were able to show that a lack of vitamin K2 leads to lower bone density and an increased risk of fractures in older women.

Another study even showed that bone loss in osteoporosis can be suppressed by large amounts of vitamin K2 (45 mg daily) and bone formation can be stimulated again.

Vitamin K1 against osteoporosis

Another study from Harvard Medical School with more than 72,000 participants showed that the more common vitamin K1 also has a positive influence on the risk of osteoporosis. It has been proven that women who consumed a lot of vitamin K1 had 30% fewer fractures (in osteoporosis) than the comparison group that consumed very little vitamin K1.

Interestingly, the test subjects’ risk of osteoporosis even increased when high vitamin D levels were combined with deficient vitamin K levels.

This result shows once again that it is extremely important to consume a balanced ratio of ALL vitamins. A balanced diet that provides all the important nutrients and vital substances is therefore the keys to health.

Vitamin K against cancer

A healthy diet can also strengthen our defenses when it comes to cancer. Our body is constantly being attacked by malignant cancer cells that are recognized and rendered harmless by the immune system. As long as we are healthy, we don’t notice it at all.

But a high-sugar, industrial-food diet and regular exposure to household toxins weaken our natural defenses and allow cancer to spread.

If you look at the following studies, vitamin K2 in particular seems to be a very important piece of the puzzle in fighting cancer.

Vitamin K2 kills leukemia cells

Vitamin K2’s anti-cancer properties appear to be related to its ability to kill cancer cells. Research using in vitro cancer cells at least shows that vitamin K2 can trigger the self-destruction of leukemia cells.

Vitamin K2 prevents liver cancer

You might be thinking, “What works in a test tube doesn’t necessarily have to work that way in real life.” That’s true, of course. However, the anti-cancer effect of vitamin K2 has also been tested in humans: for example in a study published in the Journal of the American Medical Association.

In this study, people who showed an increased risk of liver cancer were supplied with vitamin K2 via dietary supplements. These people were compared to a control group that did not receive vitamin K2. The results are impressive: Less than 10% of the subjects who received vitamin K2 later developed liver cancer. In contrast, 47% of the control group contracted this serious disease.

Vitamin K2 for calcified shoulders

The calcified shoulder makes itself feel severe pain. It develops gradually, but the pain can be there all of a sudden. Calcium deposits on the shoulder tendon attachments are responsible for this.

A good vitamin K supply could prevent the development of a calcified shoulder since the vitamin shifts the calcium into the bones and helps prevent the accumulation of calcification in the soft tissue. Of course, in addition to optimizing the vitamin K supply for the calcified shoulder, further measures are required, which you can find in the link above.

Vitamin K2 reduces the risk of death

Vitamin K2 can apparently even help people who already have cancer. Vitamin K2 consumption can reduce the risk of death in cancer patients by 30%. These results were recently published in a study in the American Journal of Clinical Nutrition.

The daily requirement of vitamin K

Looking at all of these studies, it quickly becomes clear that getting enough vitamin K is very important. The German Society for Nutrition now states the following daily requirements for young people from the age of 15 and adults:

  • Females at least 65 µg
  • men about 80 µg

However, it can be assumed that these 65 µg or 80 µg represent the absolute minimum required to maintain blood clotting and that much higher amounts of vitamin K are actually required. As is well known, vitamin K has many other tasks besides blood clotting.

Since natural vitamin K is not toxic even in large quantities and no side effects are known, it can also be assumed for this reason that the need for vitamin K is significantly higher, so there is no risk if you take more vitamin K than the officially recommended 65 µg or 80 µg.

Foods high in vitamin K1

In the following list, we have put together some foods that are particularly rich in vitamin K1, which can increase your vitamin K levels in the blood. These foods are worth including in your daily diet, not only because they meet your vitamin K needs, but also because they contain a variety of other micronutrients.

Green leafy vegetables

The need for vitamin K1 can be ensured, for example, by eating lots of green leafy vegetables such as spinach, lettuce, or purslane. However, green leafy vegetables not only contain large amounts of vitamin K1 but of course also many other health-promoting substances such as chlorophyll. Leafy greens can be used to make delicious green smoothies with the help of a blender, making it easy to increase the number of leafy greens in your diet.

If you still have problems getting enough green leafy vegetables, green drinks made from grass powder (wheat grass, Kamut grass, barley grass, spelled grass, or a combination of different grasses and herbs) are also a great alternative source of vitamin K. Barley grass juice from a high-quality source, for example, contains at least twice the recommended daily dose of vitamin K1 in a daily dose of 15 grams.

Beetroot leaves

Most people don’t even know that beetroot leaves are also considered a leafy green vegetable. They contain far more minerals and nutrients than the tuber. In the leaves of the beetroot, there is even 2000 times more vitamin K1 than in the tuber – a true source of vital substances!


Kale contains the most vitamin K1 of any vegetable. But other types of cabbage such as broccoli, cauliflower, Brussels sprouts, or white cabbage also contain a lot of vitamin K1. White cabbage also provides vitamin K2 – due to its microorganism content – when it is eaten in the form of sauerkraut. Cabbage also contains large amounts of other healthy micronutrients, which is why it is even used medicinally.


Herbs such as parsley and chives also contain a lot of vitamin K. A whole range of important vitamins can be found in parsley, making it a competitor to some supplements.


The avocado not only contains interesting amounts of vitamin K but also provides valuable fats that are necessary for the absorption of the fat-soluble vitamin. In the presence of the avocado, many other fat-soluble substances such as vitamin A, vitamin D, vitamin E, alpha and beta carotene, lutein, lycopene, zeaxanthin, and calcium are of course also better absorbed.

The foods richest in vitamin K

Below are some vitamin K values from a selection of the foods richest in vitamin K (always per 100 g of fresh food):

  • Natto: 880 mcg
  • Parsley: 790 mcg
  • Spinach: 280 mcg
  • Kale: 250 mcg
  • Brussels sprouts: 250 mcg
  • Broccoli: 121 mcg

What does MK-7 mean and what does all-trans mean?

If you want to take vitamin K2 as a dietary supplement, you will inevitably come across the terms MK-7 and all-trans. What do these terms mean?

Vitamin K2 is also called menaquinone, which is abbreviated to MK. Since there are different forms of this, they are distinguished by numbers. MK-7 is the most bioavailable (i.e. most usable by humans) form.

MK-4 is not considered to be very bioavailable, and MK-9 has not yet been extensively researched.

The MK-7 is now available in the cis or trans form. Both forms are chemically identical but have a different geometric structure so the cis form is ineffective because it cannot dock to the corresponding enzymes.

The transform of the MK-7 is thus the best and most effective form.

However, both forms can be mixed in preparations without the consumer knowing how much of one or the other is contained.

Preparations that consist of more than 98 percent of the transform are therefore referred to as all-trans to indicate that the product consists almost exclusively or even exclusively of the transform and is therefore of very high quality.

Vitamin K2 as a dietary supplement

As mentioned above, vitamin K2 is the more active K vitamin. It is also assumed that K1 is primarily used to produce blood coagulation factors, while K2 is more active in the area of calcium metabolism. Vitamin K2 is therefore particularly important when the focus is on the health of the blood vessels, heart, bones, and teeth.

There are a lot of foods available that contain vitamin K1, but not quite as many that contain vitamin K2 in relevant amounts. Anyone who is still reluctant to eat liver several times a week, has little sympathy for the Japanese soy specialty natto, and possibly only eats green leafy vegetables sparingly, quickly runs the risk of suffering from a vitamin K deficiency.

The consequences usually only appear after several years and then show up, for example, in a particular susceptibility to caries of the teeth, in dwindling bone density, in kidney stones, or in a poor condition of the heart and blood vessels.

Depending on the type of personal diet, vitamin K2 can therefore also be taken as a dietary supplement.

Vitamin K2 for vegans

If it is important to you that your vitamin K2 does not come from animals but from microbial sources, then the vitamin preparation you have chosen should contain vitamin K2 in the form of microbial menaquinone-7. Animal vitamin K2, on the other hand, is menaquinone 4 (MK-7).

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Written by Bella Adams

I'm a professionally-trained, executive chef with over ten years in Restaurant Culinary and hospitality management. Experienced in specialized diets, including Vegetarian, Vegan, Raw foods, whole food, plant-based, allergy-friendly, farm-to-table, and more. Outside of the kitchen, I write about lifestyle factors that impact well-being.

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