Vitamin K2 is, as you can probably guess, is part of the vitamin K family. You may have heard about vitamin K as being essential for blood clotting, an activity regulated by the liver. Vitamin K2, specifically as the menaquinone-7 (MK-7) form, contributes to blood clotting, but because it's the most bioavailable of the K vitamins, it's also able to extend beyond the liver to activate K-dependent proteins in other systems, such as the bones and the vasculature, or blood vessels.
Where bone health is concerned, vitamin K2 activates a protein produced by bone cells called osteocalcin, which binds calcium ions to the bone mineral matrix, thus strengthening the skeleton. But without adequate vitamin K2, osteocalcin remains inactive and calcium is not directed to create stronger bones.
So how do we get enough Vitamin K2? In truth, I find it can be tough by diet alone.
While vitamin K can be found in leafy greens and other vegetables, natural vitamin K2 is harder to obtain. Still, it can be found in animal products, as well as bacterially fermented foods like mature cheeses, especially Gouda, and natto.
So while ideally we would obtain our nutrients from food, I recommend vitamin K2 supplements as a viable and effective alternative. For example, a three-year study of healthy postmenopausal women marked the first clinical trial to show that a long-term (more than one-year) supplement of vitamin K (as MK-7) improves bone mineral density, bone mineral concentration, and bone strength.
Importantly, research also showed substantial benefits of a nutritional dose of vitamin K2 in inhibiting age-related stiffening of arteries.