Vitamin K2: The Mystery Vitamin

February 21, 2016

Most people and many health care professionals have never heard of Vitamin K2. This is truly unfortunate since it plays a key role in many health concerns, is almost non-existent in Western diets and could well be the “missing link” between our diet and osteoporosis, as well as cardiovascular disease.

What is Vitamin K?  capsules-of-omega-3

Since its discovery in 1929, vitamin K has been known primarily for its crucial role in the blood-clotting process. Vitamin K represents a family of fat soluble vitamins, of which K1 and K2 have been found to be useful for general health purposes.(1)

It was not until 1975 that researchers at Harvard Medical School identified osteocalcin, a bone protein, which led to the discovery of vitamin K2 as distinct from vitamin K1.

Since that time, scientists have uncovered compelling evidence that vitamin K2 plays an important role in bone health, as well as playing a significant role in preventing heart disease and other health issues.

What is the Difference Between K1 and K2?

Vitamin K1 is well known for being crucial for proper blood clotting.

Vitamin K2 importance goes far beyond proper blood clotting; there is a growing body of clinical evidence demonstrating its crucial significance in the fight against the most common and devastating diseases of our time: osteoporosis and cardiovascular disease.(2) These conditions contribute to significant health-care costs, are the most common causes of death worldwide. Both can be linked to a deficiency in vitamin K2.

Vitamin K2 can be further divided into several different subtypes, but the most important ones are MK-4 and MK-7.

What is the Connection Between Vitamin K2, Vitamin D and Calcium?

There is no question that calcium is an incredibly important mineral. It is far more than just a building material for bones and teeth; it plays a crucial role in all kinds of biological processes. (3)

So why is it that recent studies, including one published in the prestigious British Medical Journal, say there is no evidence that increasing calcium intake through supplementation prevents fractures and that supplementation should not be recommended?(4)

It would appear that there is more to the story. Is Vitamin D the missing component? Its importance in bone development is well established.(5) There is no doubt as to the importance of vitamin D to our health. For a detailed discussion, please refer to our article: The Growing Pandemic of Vitamin D deficiency:

There is another significant factor to be considered and that is cardiovascular disease. Many studies are now showing that calcium supplementation causes an increased risk of cardiovascular disease for both men and women.(6)

The Calcium Paradox

Dr. Kate Rheaume-Bleue, a naturopathic physician, has authored what we believe is one of the best books on this important topic: Vitamin K2 and the Calcium Paradox: How a Little Known Vitamin Could Save Your Life.

“When you take vitamin D, your body creates more of these vitamin K2-dependent proteins, the proteins that will move the calcium around. They have a lot of potential health benefits. But until the K2 comes in to activate those proteins, those benefits aren’t realized. So, really, if you’re taking vitamin D, you’re creating an increased demand for K2. And vitamin D and K2 work together to strengthen your bones and improve your heart health.

… For so long, we’ve been told to take calcium for osteoporosis… and vitamin D, which we know is helpful. But then, more studies are coming out showing that increased calcium intake is causing more heart attacks and strokes. That created a lot of confusion around whether calcium is safe or not. But that’s the wrong question to be asking, because we’ll never properly understand the health benefits of calcium or vitamin D, unless we take into consideration K2. That’s what keeps the calcium in its right place.”

In simple terms, it appears that both vitamin K1 and k2 modify proteins to allow them to bind to calcium and in this way activate the calcium binding properties of proteins.(7)

Vitamin K1’s primary function is in the liver to activate calcium-binding proteins involved in blood clotting, while vitamin K2 is used by the body to activate proteins that regulate where calcium ends up in the body. (8)

Vitamin K2 and Heart Disease

In a landmark study known as the Rotterdam study, those who had the highest intake of Vitamin K2 were 52% less likely to develop calcification of the arteries, and had a 57% lower risk of dying from heart disease, over a 7-10 year period. (9)

Another study of 16,057 women found that participants with the highest intake of vitamin K2 had a much lower risk of heart disease. For every 10 micrograms of K2 they consumed per day, the risk of heart disease was reduced by 9%. (10)

Unfortunately, this very important topic still requires further study in the form of large controlled trials. The two studies referred to above are observational studies, which do not prove cause and effect.

How do Vitamin D and K2 Work Together?

Vitamin D allows the body to absorb calcium from the intestines into the bloodstream, but it does not take the calcium to where it needs to go. That is where vitamin K2 comes in. Vitamin K2 activates two important enzymes, Matrix Gla-protein (MGP) and Osteocalcin, that move calcium around the body. When our bodies are deficient in K2, this very important function does not occur, and calcium ends up being deposited in our arteries instead of our bones, leading to a multitude of health problems.

Vitamin D’s role in the transit of calcium is equally critical, and it works synergistically with vitamin K2. When Vitamin D is deficient, K2 is left without an opportunity to escort calcium away from arteries and into bones. If vitamin D is present in sufficient quantity but you are lacking vitamin K2, calcium is likely to build up in arterial walls leading to many health issues.

Lack of vitamin K2 results in the “Calcium Paradox”, where too little calcium is utilized by the bones, resulting in weak bones, and excess calcium accumulates in the arteries, making them stiff and inelastic.

In a peer reviewed article in the Oman Medical Journal entitled Vitamin K Dependent Proteins and the Role of Vitamin K2 in the Modulation of Vascular Calcification: A Review, the authors concluded: “Vitamin K2 has promising potential to be used as treatment or prevention for the the development of vascular calcification, especially in at risk patient groups with high incidence of calcification or vitamin K deficiency.” (11)

What we have is a persuasive argument based on biological grounds and strong correlations from observational studies. Given that cardiovascular disease is the world’s most common cause of death, the importance of further study can not be overstated.
The American Heart Association reports that cardiovascular disease killed 17.3 million people in 2015, with the number expected to rise to 23.6 million by 2030. (12)

What are the Best Food Sources of Vitamin K2?

Our gut bacteria produce some K2 for us and we convert a small amount of K1 to K2 in our liver, but we must depend on dietary sources for most of our K2 requirement.

Vitamin K2 is produced by specific bacteria and the primary food source of vitamin K2 is natto (a Japanese fermented soybean dish), goose liver, and the fat (egg yolk, butter and lard) of grass-fed animals.


Natto is not widely available and is very much an acquired taste. Goose liver is a rare delicacy at best and quite expensive. What used to be our best source – animal fats – is now almost entirely lacking in K2 because of the diet of commercially raised animals. These animals need the chlorophyll in grass or other green food to convert K1 to K2 for us.

To the extent that vitamin K2 is present in dairy products, it is mostly in certain types of cheeses, such as Gouda, Brie, and Edam. It is quite difficult to get enough vitamin K2 from the standard Western diet, especially if you do not eat K2-rich natto, so taking a supplement may be the best strategy for most people.



Vitamin K2 Supplements?

There are several different forms of vitamin K2. The two primary ones are the only ones available in supplement form: menaquinone-4 (MK-4) and menaquinone-7 (MK-7).

MK-4 has a very short biological half-life of about one hour. In addition, in supplement form, the MK-4 products are synthetic, thus making it a poor candidate as a dietary supplement.

MK-7 stays in your body longer; its half-life is three days, meaning you have a much better chance of building up a consistent blood level. MK-7 comes from a natural fermentation process from natto.
Furthermore, it has recently been shown that MK-7 also helps prevent inflammation by inhibiting pro-inflammatory markers produced by white blood cells called monocytes.(13)

With regard to the appropriate dosage, some studies have shown as little as 45 micrograms per day is sufficient. Dr. Dennis Goodman, the chair of the Department of Integrative Medicine at New York University (NYU), in his excellent book, Vitamin K2: The Missing Nutrient for Heart and Bone Health, recommends taking 180 micrograms per day in the form of MK-7 and if you choose to eat natto, all you need is about one teaspoon to meet your 180 micro-gram target.

On the positive side, unlike most fat soluble vitamins, vitamin K2 is virtually non-toxic and there is not much danger of overdosing.(14) Finally, because it is fat soluble, it is best to take your vitamin K2 supplement with a healthy fat, like coconut oil, to improve its absorb-ability.

How Can you Tell if you are Vitamin K2 Deficient?

It is not easy. Unlike Vitamin D there is no easily available way to screen or test for vitamin K2 deficiency. Vitamin K2 cannot so far be measured directly; it is measured through an indirect assessment of undercarboxylated osteocalcin. Unfortunately, this test is still not commercially available.

Without an available test, we are left with looking at lifestyle factors that may indicate signs of deficiency. In general, if you have any of the following health conditions, you are likely deficient in vitamin K2: Osteoporosis, Heart disease or type 2 diabetes. In addition, given the low likelihood that you are getting very much vitamin K2 from your diet, its low toxicity and its potential health significance, it makes sense for virtually everyone to supplement.

Recent Studies Pertaining to Vitamin K2 and its Health Benefits

A study published by the European Prospective Investigation into Cancer and Nutrition (EPIC) has revealed that increased intake of vitamin K2 may reduce the risk of prostate cancer by 35 percent. 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 study.(15)

In another interesting study published in the Oxford Journals in 2013, two hundred chronic kidney dialysis patients suffering from advanced calcification of the arteries were recruited to randomly receive 360, 720 or 1080 µg of MK-7 three times weekly for 8 weeks. They found that the calcification levels decreased by 17, 33 and 46% in the respective groups. They concluded that MK-7 “supplementation may be a novel approach to prevent vascular calcifications in chronic haemodialysis patients.(16)

These studies form part of a small but growing body of science supporting the potential health benefits of vitamin K2 for bone, cardiovascular and prostate health.


There remains a desperate need for large randomized studies on K2 and its potential health benefits. However, the studies that do exist are very persuasive as to vitamin K2’s health benefits. Since vitamin K2 has been shown to be biologically effective, it is clearly an important nutrient for human health, although one of the most poorly understood by medical authorities and the general public.  Our apple rating:  5