The only known unequivocal biological role of vitamin K is as a cofactor for an enzyme that enables specific proteins to bind calcium (3, 4). The ability to bind calcium ions (Ca2+) is required for the activation of the seven vitamin K-dependent blood clotting (‘coagulation’) factors (e.g., prothrombin), or proteins, in the series of events that stop bleeding through clot formation (‘coagulation cascade’). Vitamin K-dependent coagulation factors are synthesized in the liver. Consequently, severe liver disease results in lower blood levels of vitamin K-dependent clotting factors and an increased risk of uncontrolled bleeding (‘hemorrhage’)(5).
In addition, three vitamin-K dependent non-clotting proteins have been characterized more precisely. One protein, ‘osteocalcin’, is regulated by vitamin D and needs vitamin K for its mineral-binding capacity related to adding mineral to the bone matrix (‘bone mineralization’) in normal bone growth and development (4, 6,7).
The calcification-inhibiting ‘matrix gla protein’ (MGP) is thought to play a role in blood vessel health (8). It can be found in numerous body tissues such as heart, kidney, lung, and bone (together with ‘osteocalcin’).
Another vitamin K-dependent protein, ‘Gas6’, appears to be a cellular growth regulation factor with cell-signaling activities important for diverse cellular functions, including cell division, and protection against programmed cell death (‘apoptosis’) (3). In addition, it may also play important roles in the developing and aging nervous system (9, 10).
The European Food Safety Authority (EFSA), which provides scientific advice to assist policy makers, has confirmed that clear health benefits have been established for the dietary intake of vitamin K in contributing to:
Authored by Dr Peter Engel in 2010, reviewed and updated by Dr Szabolcs Peter on 18.06.2017
