Vitamin K2 CAS 11032-49-8 Nutritional enhancer

Vitamin K2, the main storage form in animals, has several subtypes, which differ in isoprenoid chain length. These vitamin K2 homologues are called menaquinones, and are characterized by the number of isoprenoid residues in their side chains. Menaquinones are abbreviated MK-n, where M stands for menaquinone, the K stands for vitamin K, and the n represents the number of isoprenoid side chain residues. For example, menaquinone-4 (abbreviated MK-4) has four isoprene residues in its side chain. Menaquinone-4 (also known as menatetrenone from its four isoprene residues) is the most common type of vitamin K2 in animal products since MK-4 is normally synthesized from vitamin K1 in certain animal tissues (arterial walls, pancreas, and testes) by replacement of the phytyl tail with an unsaturated geranylgeranyl tail containing four isoprene units, thus yielding menaquinone-4. This homolog of vitamin K2 may have enzyme functions distinct from those of vitamin K1.

Menaquinone-7 is different from MK-4 in that it is not produced by human tissue. MK-7 may be converted from phylloquinone (K1) in the colon by Escherichia coli bacteria.However, bacterially derived menaquinones (MK-7) appear to contribute minimally to overall vitamin K status.MK-4 and MK-7 are both found in the United States in dietary supplements for bone health.

The U.S. Food and Drug Administration (FDA) has not approved any form of vitamin K for the prevention or treatment of osteoporosis. MK-4 (45 mg daily) has been approved by the Ministry of Health in Japan since 1995 for the prevention and treatment of osteoporosis.

All K vitamins are similar in structure: they share a "quinone" ring, but differ in the length and degree of saturation of the carbon tail and the number of "side chains". The number of side chains is indicated in the name of the particular menaquinone (e.g., MK-4 means that four molecular units – called isoprene units – are attached to the carbon tail) and this influences the transport to different target tissues.

Health effects

Vitamin K2 has only begun to be studied, and the few studies on humans suffer from either a small number of test subjects or that the study has yet to be reproduced by an independent team. The possible health benefits which those studies have suggested may be worth further investigation are mostly related to bone strength and arterial health (reducing calcification or even decalcifying, with a possible reduction in blood pressure).