02 March 2011

Vitamin K2: Building bones while beating back arterial calcification

Vitamin K2's time to shine has come—move over vitamin D! Once only known for its role as a "koagulation" factor in blood clotting, vitamin K2 is emerging as another fundamental anti-aging nutrient. While vitamins D and E have garnered the majority of interest in the last decade, the impact of vitamin K2 on aging bones and hearts demands that we give it equal attention.

Whereas most vitamin and mineral supplements use vitamin K in its form of K1 (phylloquinone sourced from plants) because it is easily available and cheap, it is the natural form of K2 (menaquinone sourced from friendly bacteria) that is the most biologically active and shown to enhance both bone formation and vascular health.

The full compilation of recent research underscores the idea that K1 and K2 should be appreciated as separate nutrients with distinct physiological actions and benefits. K1 is the more familiar vitamin known for its key role in directing blood-clotting in the body and the one given as a shot at birth (a common practice in many countries to curtail hemorrhage incidents in newborns.) The picture for K2 seems to be a bit more varied and is key in regulating calcium balance.

Vitamin K2 acts by activating the bone-building hormone (carboxylating osteocalcin) to clear calcium from the arteries and use it in bone mineralization. It effectively removes calcium that would otherwise end up deposited in arterial plaques. Since protecting arteries and soft tissues from calcification is one of the most important ways to stave off the ravages of aging on the body, consuming enough vitamin K2 daily is key for a long, healthy life.

Getting Enough K2

Because vitamin K2 is synthesized by friendly bacteria in the intestine, nutrition scientists have long assumed that that deficiencies were rare. However, new data are showing that intestinally synthesized vitamin K is not absorbed as easily as previously thought. Vitamin K also preferentially accumulates in the liver where it does have a clotting factor role.

In fact, once overlooked because "time to clot" was the test for vitamin K status, it is here where we are now seeing new signs of vitamin K deficiency previously only seen with vitamin D deficiency—fragile, brittle bones and increased fractures—even with adequate calcium and vitamin D.

Most people in North America should increase amounts consumed daily. The evidence finds that only with much higher intake do bone cells get their share and the same holds true for removal of calcium in arteries.

People can obtain enough vitamin K2 by eating plenty of fermented foods such as cheese, sauerkraut, and natto (a traditional Japanese soy-based food). Supplementation is another viable option as achieved with a quality multivitamin.

Regardless of how one gets it, it’s important not to underestimate value of this underdiscussed nutrient and to understand that most people are not getting enough. Consuming sufficient amounts of K2 along with a healthy diet will increase odds of a healthier life with clear arteries and stronger bones.


McCann and Ames. Vitamin K, an example of triage theory: is micronutrients inadequacy linked to diseases of aging?. Am J Clin Nutr 90:889-907, 2009.
Vitamin K2. Monograph. Alternative Medicine Review 14(3):284-293, 2009.
Koitaya. Et al. Effect of low dose vitamin K2 (MK-4) supplementation on bioindices in postmenopausal Japanese women. J Nutr Sci Vitaminol. 55:15-21, 2009.
Gast, et al. A high menaquinone intake reduces the incidence of coronary heart disease. Nutr Metab Cardiovas Dis 19:504-510, 2009.
Shea, et al. Vitamin K supplementation and progression of coronary artery calcium in older men and women. Am J Clin Nutr 89: 1799-1807, 2009.
Shea MK, Booth SL Update on the role of vitamin K in skeletal health. Nutr Rev 66(10):549-57, 2008.

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