Best Vitamin K Supplements: Top 10 Vitamin K Brands Reviewed

What Is Vitamin K

Vitamin K, together with vitamins A, E and F is one of the four fat-soluble vitamins. It was discovered back in 1929 by the Danish biochemist Henrik Dam.

Due to its ability to promote blood clotting (coagulation) and the fact that the discovery was made in Germany, where the word coagulation is written as Koagulation, this vitamin has earned its letter K.

When talking about vitamin K, we not only mention just one compound but 13. Vitamin K is a collection of molecules with similar structures, which are divided into two subcategories - vitamin K1, known as phylloquinone, and vitamin K2, known as menaquinone.

With Vitamin K2 things get a little complicated. It is built by a group of substances, called menaquinones that are divided into short-chain and long-chain ones. 

​Their names begin with the letters MK. There are three synthetic forms of the vitamin - K3, K4, and K5. In all three on the group, only vitamin K3 shows signs of toxicity and therefore is banned in many countries.

​Sources of Vitamin K

​Depending on its shape, the vitamin might be found in different foods. K1 can be found in plant food sources, particularly in the green leafy vegetables. Some of the richest foods in vitamin K are kale, spinach, broccoli, Brussels sprouts, and asparagus.

From the K2 and short-chain family, the most important is MK-4, which can be found in small amounts in animal food sources - eggs and meat. MK-7, MK-8, and MK-9 are the best known from the long-chain ones. 

They are found in great quantities in fermented foods, especially different fermented cheeses and the traditional Japanese dish Nattō. Nattō is perhaps the best source.  Although we get the majority of vitamin K in the form of K1, K1 gets converted into MK-4 in our body.

Vitamin K can be found as a nutritional supplement. While K1 and K2 can be equally effective, we recommend the use of MK-7. Vitamin K2 MK-7 shows a much longer half-life, more stable plasma levels, and better accumulation with a continuous intake.

​What Are Its Physiological Properties

​​Vitamin K is responsible for two very important things – it regulates the blood clotting and supports bone strength and their density. The way of action is complex so we will save you much of the biology and chemistry. 

Briefly, the action mechanism is done through the so-called Vitamin K cycle. Vitamin K is necessary for the synthesis of gamma-carboxyglutamate from glutamate. 

​The synthesized gamma-carboxyglutamate is required for the functioning of certain proteins involved in blood clotting and bone metabolism. If the vitamin is lacking, these proteins remain inactive and do not do any work.

​Additional Properties and Efficiency

In recent years, vitamin K has become a major recommendation for people with impaired bone metabolism. Especially for menopausal women diagnosed with low bone density. 

Although a firm conclusion cannot be made at this stage, it is a fact that vitamin K is found in the bones. It is a fact that vitamin K is responsible for the work of an important protein in the bones, called osteocalcin. 

Osteocalcin is responsible for the building of the bones. From a scientific point of view, there is research in favor of the hypothesis of bone density and strength and also research against it.

​My observations show that even up to this moment one cannot say that vitamin K can completely stop the reduction of bone density in the respective risk groups. However, it can significantly reduce the loss of the bone mass, as its combination with vitamin D is of great importance. But many factors need to be studied.

Vitamin K is recommended for reducing pathologic calcification. Things look better with the pathological calcification, as data supporting the effectiveness of vitamin K to reduce pathologic calcification increase significantly and the positive impact of vitamins can be considered confirmed.

​What Is the Recommended Intake

​At this stage, the recommended intake varies between different countries, different age groups, and gender. Women need less as compared to men and the recommended dosage for them varies between 60 and 100 mcg per day. 

​Men are recommended to take between 80 and 120 mcg daily. It is important to note that the above-mentioned recommendations are for vitamin K1 and these recommendations are based on an average intake of vitamin K from food.

At this stage, we do not have enough data to give precise recommendations for vitamin K2. The lack of sufficient scientific data is the reason why we still do not know exactly how much vitamin K is needed for optimal health.

The quantity for avoiding health problems is known, but it is yet to be learned whether and how much further we can take this vitamin and still expect additional health benefits.

If you take it as a dietary supplement, seek to take doses of 200-300 mcg. It is strongly recommended to take the supplement with meals high in fat because they significantly improve the assimilation of vitamins.

​Are We Getting Enough of Vitamin K

​At this stage the vitamin K deficiency is rare and most people, having at least some decent kind of diet that includes vegetables, manage to get enough of the vitamin and to avoid the presence of health problems.

The lack of the vitamin can be a problem to people with impaired liver function, people on dialysis who suffer from celiac disease (gluten enteropathy), people diagnosed with Crohn's disease, and people taking anticoagulants.

Light vitamin deficiency does not lead to significant problems, while serious deficiency leads mostly to bleeding.

​Possible Side Effects of Vitamin K

​The interesting fact with vitamin K is that at this stage there is not a scientific study, showing toxicity or other side effects in people with normal blood clotting. This last thing is very important for people taking anticoagulants based on coumarin (e.g. the drug Warfarin) because vitamin K can be very dangerous.

Regardless of its form, the vitamin reacts with the effectiveness of the anticoagulants and it decreases that effect significantly. This can lead to internal bleeding and other complications.

On the other hand, the intake of anticoagulants reduces the levels of vitamin K and it becomes a necessity. Ask your doctor whether and in what quantities you should take vitamin K.

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