Osteoporosis, the loss of bone mineral density, and vascular calcification, a hardening of veins and arteries due to the presence of calcium deposits, have long coexisted in elderly populations. While these health conditions have been considered to occur independently of one another, evidence suggests that a vitamin K2 deficiency may be a missing link, responsible for the positive association between one condition and another.
 
In recent years, studies conducted on vitamin K2 have found that this micronutrient has a beneficial role in maintaining calcium homeostasis – calcium is more effectively retained in bone tissue, while the nutrient prevents calcium from depositing on vessel walls. A recent review, published in the journal Nutrients by researchers at the Center for Advanced Studies and Technology, calls for further clinical studies investigating the apparent role that vitamin K2, a form of the vitamin known as menaquinone, has in benefitting how the body uses calcium, ensuring that it is retained by the bone, rather than being deposited throughout the vascular system where it contributes to the risk of cardiovascular diseases and adverse events.
 
“In particular, vitK2 deficiency seems to be responsible for the so-called ‘calcium paradox’ phenomenon, characterized by low calcium deposition to the bone and its accumulation in the vessel wall,” the authors said. “Since these effects may have important clinical consequences, and the role of vitK2 in bone-vascular crosstalk has only partially been explained, this review focuses on its effects on the bone and vascular system by providing a more recent literature update. Overall, the findings reported here propose the vitK2 family as natural bioactive molecules that could be able to play an important role in the prevention of bone loss and vascular calcification, thus encouraging further in-depth studies to achieve its use as a dietary food supplement.”
 
Vitamin K2 has unique mechanisms of action compared to vitamin K1, based on chemical differences. While vitamin K1 is abundantly concentrated in the liver, “the various K2 isoforms show different bioavailability, and there is a direct correlation [to] intestinal uptake and bioavailability in the human body,” the authors wrote.
 
In simple terms, at the vascular level, vitamin K2 engages in what researchers refer to as bone-vascular crosstalk, by acting as a cofactor for certain enzymes which make active MGP more abundant, which inhibits calcium from precipitating in blood vessels via multiple mechanisms of action, including MGP itself directly inhibiting calcium precipitation from occurring. In bone tissue, MGP exerts multiple protective effects against oxidative stress which effects bone calcium deposits.  
 
“These interesting molecular effects exerted by vitK2 support the results of the pre-clinical and clinical studies reported here, implying that it can significantly promote bone and vascular health,” the authors wrote. “Therefore, vitK2 could be recommended as a natural bioactive compound potentially able to prevent and/or treat metabolic bone and vascular disease such as osteoporosis and vascular calcification.”