Vitamin K is a cofactor for enzymatic modification of glutamic acid residues (Glu) to gamma- carboxyglutamic acid residues (Gla) in vitamin K-dependent Gla proteins. These Gla proteins are necessary for hemostasis, bone metabolism, vascular calcification and cell proliferation. Vitamin K is found in nature as phylloquinone (vitamin K1) in green leafy vegetables, algae and some plant oils, and menaquinones (vitamin K2 also termed MK-n, where n is the number of isoprenoid units) can be found in meat, eggs and fermented food. A synthetic form of vitamin K menadione (vitamin K3) can be found as an additive in some animal feeds.