Vitamin K is actually a group of vitamins required for blood to clot properly. In the human diet, Vitamin K consists of Vitamin K1 (phylloquinone) and several forms of Vitamin K2 (menaquinones). Vitamin K2 members, menaquinones, are called MK-4 through MK-10 (based on the number of side chains).
Best known as a required nutrient for blood coagulation, research now indicates that vitamin K is also required for healthy bones and blood vessels.
Researchers believe that inadequate dietary vitamin K may lead to calcification of blood vessels and increased risk of coronary heart disease. In a recent study, researchers in the Netherlands compared dietary intakes of vitamin K with the occurence of coronary heart disease, all cause mortality and aortic calcification. They also evaluated the potential effect of dietary vitamin K on cholesterol levels. They analyzed dietary and medical data of 4,807 people, and the cholesterol levels of 3,370 people for their study.
Most people in Western populations obtain vitamin K from a variety of sources:
-Vitamin K1 (Phylloquinones) from dark-green leafy vegetables and vegetable oils
-Vitamin K2 as Menaquinone MK-4*, from meat & eggs
-Vitamin K2 as Menaquinones MK-5 through MK-10 from cheese and fermented foods
The researchers found that after correction for age and other risk factors, higher dietary amounts of vitamin K2 (menaquinones, including menatetrenone) reduced the risk of Coronary Heart Disease Mortality by 27%, and severe aortic calcification by 29%. This study grouped all forms of Vitamin K2 together. Dietary vitamin K2 was also associated with reduced total cholesterol and increased HDL. The effect of vitamin K2 was evaluated in people who were not on cholesterol lowering medication. Dietary Vitamin K1 did not show these protective effects in this study.
The researchers concluded, "An adequate intake of menaquinone (K2) could be important for CHD prevention."
*MK-4 is also named Menatetrenone.
Geleijnse and others. "Dietary Intake of Menaquinone Is Associated with a Reuced Risk of Coronary Heart Disease: The Rotterdam Study." J Nutr. 2004;134:3100-3105.