Vitamin K2 (menaquinones, such as MK-7) has gained attention because it may remain in circulation longer and is studied in bone/vascular pathways. The rationale: vitamin D increases calcium handling, while K2 helps activate proteins like osteocalcin and MGP through carboxylation. This may support calcium use in bone and potentially limit unwanted deposition in vessels. Some studies report biomarker changes (e.g., reduced inactive MGP), but it is not a universal rule. Decisions should be individualized based on vitamin D status, diet, bone health, cardiovascular risk, and medications—especially anticoagulants.