Vitamin K, a fat-soluble vitamin, is primarily known for its role in regulating blood coagulation. Vitamin K exists in two major forms: phylloquinone and the menaquinones. Phylloquinone, designated as vitamin K1, is the major dietary form in food. Menaquinones are designated as vitamin K2 and are named MK-7, MK-8 and MK9, according to the length of structurally related molecular side chains attached to the parent molecule. Fermented foods contain substantial amounts of K2 and MK-7 is the primary menaquinone found in fermented foods. MK-7 contributes to optimum vitamin K storage in the body, and functions more effectively as a co-factor for the activation of osteocalcin which is critical for bone strength. A large-scale study on vitamin K intakes among 5,000 Dutch persons suggests that vitamin K2 may help maintain healthy blood vessels.Compared to those in the low vitamin K2/menaquinone group, subjects at the highest consumption level of vitamin K2 had substantially superior heart health. Similar associations were not seen for vitamin K1.