**Abstract**

Vitamin K is an essential fat-soluble vitamin. The role of vitamin K as a cofactor involved in blood coagulation is well demonstrated. In the past two decades, vitamin K has been receiving more attention due to its role in bone health and metabolism. Vitamin K plays a role in activation of vitamin K-dependent proteins, which are involved not only in blood coagulation but in bone metabolism and the inhibition of arterial calcification. Numerous studies have exhibited the importance of vitamin K in bone health. The bone mineral density (BMD) does not remain steady with age, particularly declining after menopause. Osteoporosis is a metabolic bone disease of reduced bone density, fragile bone, and elevated susceptibility to fracture. A greater understanding of the biological linkages between vitamin K and bone may conduce to new treatment for osteoporosis that may improve bone density and prevent the adverse outcomes of osteoporosis.

**Keywords:** vitamin K, phylloquinone, menaquinone, bone mineral density, osteoporosis, Gla protein
