Vitamin K2: the nest blockbuster supplement?

Better Nutrition, Sept, 2007 by Martin Zucker

Researcher in Europe are focusing attention on a member of the vitamin K family that seems to deliver significant bone and heart benefits to supplement users.

The nutrient is a subtype of vitamin K2 called MK-7. "It has all the makings of becoming a future nutritional blockbuster," says Connecticut-based cardiologist and nutrition expert Stephen T. Sinatra, MD.

K2 helps put calcium in the bones, where you want it, and keeps it out of your artery walls, where you definitely don't want it, he says. "K2 could be a doctor's dream--a double-barreled protector against osteoporosis and arterial calcification, a common contributor to dangerous, vulnerable plaques prone to rupture and a cause of heart attacks and stroke."

Most supplement users are vaguely familiar with vitamin K, a nutrient found in green leafy vegetables that has been synthesized as an ingredient in supplements. Discovered by Danish scientists in 1929, Vitamin K plays a vital role in the coagulation of blood. In fact, its name comes from the Danish word koagulation.

Vitamin K2 has a somewhat different chemical structure from vitamin K1, along with a growing reputation to impact both bone and arterial health. K2 serves as a critical partner in the body's construction of healthy bones. The body uses a protein called osteocalcin to carry calcium from the blood and knit it into the bone matrix. Without enough K2, the calcium becomes deposited in arterial walls, where it doesn't belong.

Beneficial bacteria in our intestines are able to produce a limited amount of K2 from vitamin K. Another source is food. The richest concentration of K2 is found in natto, a Japanese fermented soybean dish. And it's interesting to note that in Tokyo, where natto is very popular, there is a low incidence of osteoporosis compared to areas of Japan were natto is less popular.

However, before you rush out to an Asian grocer to stock up on natto, you should be forewarned that its taste is not considered pleasant. Most Westerners are turned off by it unless they apply some creative, palatable spicing.

Most cheeses contain what is considered a protective amount of K2, though hardly as much as what's found in natto. Each 100 g (about 4 oz.) of natto contains 1,000 mcg of K2 compared to 30-60 mcg in an equal amount of cheese.

Supplements offer another option for obtaining K2. Two K2 subtypes are available today in health food stores. A synthetic form called MK-4 has been used commercially for about 20 years. As mentioned earlier, researchers in Holland have published findings within the past few years on another subtype--MK-7 derived from natto--that seems to have significant effectiveness in the body.

According to Leon Schurgers and Cees Vermeer of the University of Maastricht in the Netherlands, MK-7 appears to be superior in terms of activity in the body and ability to activate the specific vitamin K proteins that clear calcium from the arteries and put it in bones. The researchers are now conducting clinical studies in several European countries with both children and adults to learn more about MK-7's potential.

If you are looking for K2 benefits in supplements, you can find products with either MK-4 or MK-7. The research to date suggests an effective daily dosage of MK-4 at around 45 mg while MK-7 shows effectiveness at a much lower level, 150 mcg.

Individuals taking anticoagulant medications, such as Coumadin, should consult their doctors before using any vitamin K supplements, which may interfere with the drug.

QUICK TIP

Avoid K2 if you are taking coumarin drugs, which prevent blood clot formation. Vitamins K and K2 (including MK-7) do the opposite and can A interact.