Vitamin K2 (MK-7)
The menaquinone-7 (MK-7) form of vitamin K2 -- the form with the longest half-life and best absorption among K2 variants. Vitamin K2 activates two critical proteins: osteocalcin, which binds calcium into bone matrix, and matrix Gla protein (MGP), which inhibits calcium deposition in arteries. In practical terms, K2 helps direct calcium into bone and away from blood vessel walls. This is why K2 supplementation is increasingly recommended alongside calcium and vitamin D3 for bone health -- the three nutrients work as a system. Typical supplemental dose is 100-200 mcg daily. Interacts with warfarin; consult a physician if on anticoagulant therapy.