Vitamin K is a name given to a group of fat-soluble vitamins. They are considered essential co-factors in humans for the production of several proteins that are involved in coagulation homeostasis and calcium homeostasis. The original term vitamin “K” comes from the K in the Germanic word Koagulation meaning the ability to clot blood or prevent hemorrhage. The first one discovered was Phylloquinone or K1, which plays an important role in blood clotting and bone metabolism. Vitamin K1 is found in green leafy vegetables, and helps bones absorb and store calcium.