We’ve seen a lot of confusion around the differences between vitamins K, K1 and K2. We’d like to help clear things up.
Vitamin K is a fat-soluble vitamin that exists naturally in multiple forms, K1 (phylloquinone) or K2 (menaquinone).
Vitamin K1 is found in high amounts in leafy green vegetables. It has a short half-life, and is mainly used by the liver to support blood clotting. Deficiencies are rare.
Vitamin K2: also known as menaquinone, is normally found in animal-derived and fermented products. Unlike K1, Vitamin K2 is used not just by the liver, but also by our bones and vasculature.
It activates many calcium-binding proteins, such as osteocalcin or matrix Gla protein, which play roles in building and maintaining bone mass, and preventing calcification of the arteries and other soft tissues, respectively. Many of us are deficient in vitamin K2.