Vitamin K is the generic name used for a family of related compounds with similar gamma-carboxylation activity.* The vitamin K family is divided into three main subsets: phylloquinone (vitamin K1), menaquinones (vitamin K2), and menadione (vitamin K3).
Most of them have similar functions in the body, mainly related to the gamma-glutamyl carboxylation of specific protein bound glutamate residues (Gla proteins).* For example, in the liver, vitamin K-dependent Gla proteins are the pro-coagulant Factors II (prothrombin), VII, IX, X and the anti-coagulant protein C, S & Z. These vitamin K-dependent factors are indispensable for the maintenance of a healthy hemostasis.* Other known vitamin K-dependent proteins are :
- Osteocalcin, the second most abundant protein in bones, which is involved in bone metabolism.*
- MGP (matrix Gla protein) and periostin are found in cartilage and bone tissues.* MGP is also present in arterial wall where it regulates calcification.*
Research on the subject of vitamin K-dependent proteins is very active, and new discoveries are being made on a regular basis, most notably for the different forms for vitamin K2.
The main differences between each form of vitamin K are their chemical structures, their dietary sources, and the way the body handles each compound. Vitamin K1 is the main dietary source of vitamin K in the Western diet. It is mainly found in green leafy vegetables. Vitamin K2 is a heterogeneous group of compounds found in foods of animal origin, fermented foods, and is produced by the intestinal microbiota.
K1 is known to be relatively poorly absorbed when obtained from vegetables. Clinical data suggest that long-chain forms of vitamin K2 from food are substantially better absorbed than K1 from green vegetables. Furthermore, in the body, vitamin K1 is known for its high turnover, small body pool, and short half-life. Vitamin K2 forms have half-lives that vary from about one hour for MK-4 to several days for MK-7. This longer presence in the bloodstream typically results in a better availability of these compounds for use in the peripheral tissues, especially when compared to K1, which is mainly confined to the liver.
While vitamin K1 functions and disposition in the body are well established, the functions and pharmacology of the different menaquinones aren’t as well known. The current scientific paradigm it that menaquinones are not only heterogeneous in their structures but also in their functions and the ways the body dispose of them. As an active area of investigation, scientists are consistently discovering new health-positive properties for each form of vitamin K2, most notably for MK-4 and MK-7. These two forms of vitamin K2 are readily available as dietary supplements.
As a practitioner, there is a choice of several different forms of vitamins K that can be tailored to create a supplementation protocol that meets your patients’ needs in terms of general, bone, or cardiovascular health.*
Protocol For Life Balance® offers seven products with vitamin K, comprising several forms, from the classic K1 to MK-7, stand-alone products, as well as vitamin K blended with other vitamins and minerals.