Vitamin K2

Vitamin K2 (MK-4 and MK-7) is a cofactor for the carboxylation of osteocalcin in bone and matrix Gla protein in the vessel wall, the step that lets those proteins do their work (Schurgers 2007, PMID: 17158229). MK-7 is absorbed well, peaks in serum at 4 hours, has a much longer half-life than short-chain vitamin K1, and accumulates to 7- to 8-fold higher serum levels during prolonged intake, so one daily dose holds serum levels steadier. In the Rotterdam Study, the highest tertile of dietary menaquinone intake was associated with lower odds of severe aortic calcification (OR 0.48) and lower coronary heart disease mortality (RR 0.43) versus the lowest tertile, but that is observational dietary data, not a supplement trial (Geleijnse 2004, PMID: 15514282). The human trials summarised below used MK-7 at 50 to 720 µg/day; the three-year bone and arterial stiffness trials used 180 µg/day of MenaQ7 branded MK-7 (Knapen 2013, Knapen 2015). Anyone taking a vitamin K antagonist such as warfarin should speak to their prescriber first, because preparations supplying 50 µg/day or more of MK-7 may interfere with that treatment (Schurgers 2007). for the combined D3 and K2 form.