A study recently 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 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 now prostate health.
Unfortunately, many people are not
aware of the health benefits of vitamin K2. The K vitamins have been
underrated and misunderstood up until very recently in both the
scientific community and the general public.
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 vitamin K2′s role in the body extends far beyond blood
clotting to include protecting us from heart disease, ensuring
healthy skin, forming strong bones, promoting brain function,
supporting growth and development and helping to prevent cancer –
to name a few. In fact, vitamin K2 has so many functions not
associated with vitamin K1 that many researchers insist that K1 and
K2 are best seen as two different vitamins entirely.
A large epidemiological study from the
Netherlands illustrates this point well. The researchers collected
data on the vitamin K intakes of the subjects between 1990 and 1993
and measured the extent of heart disease in each subject, who had
died from it and how this related to vitamin 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
vitamin K2 intakes were 52 percent less likely to develop severe
calcification of the arteries, 41 percent less likely to develop
heart disease, and 57 percent less likely to die from it. (Geleijnse
et al., 2004, pp. 3100-3105) However, intake of vitamin K1 had no
effect on cardiovascular disease outcomes.
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, such as the soft tissues.(Spronk et al.,
2003, pp. 531-537) In an acknowledgment of the different roles played
by vitamins K1 and K2, the United States Department of Agriculture
(USDA) finally determined the vitamin K2 contents of foods in the
U.S. diet for the first time in 2006. (Elder, Haytowitz, Howe,
Peterson, & Booth, 2006, pp. 436-467)
Another common misconception is that
human beings do not need vitamin K2 in their diet, since they have
the capacity to convert vitamin K1 to vitamin K2. The amount of
vitamin K1 in typical diets is ten times greater than that of vitamin
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 vitamin 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 vitamin K2 in the diet is that epidemiological and
intervention studies both show its superiority over K1. Intake of K2
is inversely associated with heart disease in humans while intake of
K1 is not (Geleijnse et al., 2004, pp. 3100-3105), and vitamin K2 is
at least three times more effective than vitamin K1 at activating
proteins related to skeletal metabolism. (Schurgers et al., 2007) And
remember that in the study on vitamin K2′s role in treating
prostate cancer, which I mentioned at the beginning of this article,
vitamin K1 had no effect.
All of this evidence points to the
possibility that vitamin K2 may be an essential nutrient in the human
diet. So where does one find vitamin K2 in foods? The following is a
list of the foods highest in vitamin K2, as measured by the USDA:
Foods high in vitamin K2
Natto
Hard cheese
Soft cheese
Egg yolk
Butter
Chicken liver
Salami
Chicken breast
Ground beef
Unfortunately, precise values for some
foods that are likely to be high in K2 (such as organ meats) are not
available at this time. The pancreas and salivary glands would be
richest; reproductive organs, brains, cartilage and possibly kidneys
would also be very rich; finally, bone would be richer than muscle
meat. Fish eggs are also likely to be rich in K2.
It was once erroneously believed that
intestinal bacteria are a major contributor to vitamin K status.
However, the majority of evidence contradicts this view. Most of the
vitamin K2 produced in the intestine are embedded within bacterial
membranes and not available for absorption. Thus, intestinal
production of K2 likely makes only a small contribution to vitamin K
status. (Unden & Bongaerts, 1997, pp. 217-234)
On the other hand, fermented foods,
however, such as sauerkraut, cheese and natto (a soy dish popular in
Japan), 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. A recent study demonstrated that MK-7 increased the percentage
of osteocalcin in humans three times more powerfully than did vitamin
K1. (Schurgers & Vermeer, 2000, pp. 298-307)
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. As mentioned previously in this paper, he found that
the Activator X concentration varied 50-fold. Animals grazing on
vitamin K-rich cereal grasses, especially wheat grass, 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 top soil that had such
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.
New research which 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.
Recommended links
On the Trail of the Elusive X-Factor
The Vitamin You Need to Prevent
Prostate CancerK2 Associated with Reduced Risk of
Coronary Heart Disease
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