Vitamin K2: The Missing Nutrient

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

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)

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.

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.