You may not know it yet, but Vitamin K is important for bone and cardiovascular health. There are two forms of vitamin K.
Phylloquinone (vitamin K-1) can be found in dark green, leafy vegetables such as broccoli, spinach and kale. Menaquinones (vitamin K-2) is contained in egg yolks, fermented foods and meat. The gut can manufacture K-2 via fermentation of microflora ("good" bacteria).
Vitamin K-2 seems to be the best choice for cardiovascular health, regulating blood's clotting factor. It will inhibit clotting when blood vessels are healthy, and enhances clotting when blood vessels are damaged.
"Arterial calcification is a significant risk factor for atherosclerosis, heart attack and stroke. In the past, it was thought that this calcification was irreversible and signaled the end stages of cardiovascular disease. However, a 2007 study using rats found that diets rich in vitamin K actually reduced the arterial calcification by approximately 50%."
Vitamin K-2 also helps to slow and reverse bone loss.
http://www.prohealth.com/library/showArticle.cfm?libid=15421&B1