Vitamines et minéraux

Vitamin K₂ and Bone Quality

Abstract

Toshiro Sato

Vitamin K is a cofactor required for post-translational gamma-carboxylation of vitamin K-dependent proteins, including coagulation and anti-coagulation factors; osteocalcin (OC), essential for bone metabolism; and matrix Gla proteins (MGP), an inhibitor of artery calcification. In addition to activation of OC, vitamin K2 induces collagen accumulation in the bone matrix. The principle effects of vitamin K on bone health are not to increase bone mineral density but to promote bone quality and bone strength. Vitamin K2, as menaquinone-7 (MK-7), is the only major vitamin K homolog which can activate OC at nutritional doses. The higher efficacy of MK-7 is due to its better bioavailability and longer half-life compared to other vitamin K homologs. Furthermore, a normal nutritional intake of MK-7 has been shown to activate MGP, which inhibit artery calcification, and has been associated with prevention of cardiovascular diseases. Thus, MK-7 is thought to contribute to calcium homeostasis in arteries as well as bones