Vitamin K2 (menaquinone-7, MK-7)

Menaquinone-7 is a long-chain form of vitamin K2 in which the side chain has seven isoprene units, giving it a longer half-life than vitamin K1 (phylloquinone) or MK-4. Like other vitamin K vitamers, it serves as a cofactor for the gamma-carboxylation of Gla proteins, including osteocalcin (bone) and matrix Gla protein (vascular wall). Dietary sources are limited: natto (a Bacillus subtilis-fermented soy food) is by far the richest, with smaller amounts in cheese and fermented dairy. In a 3-year RCT in 244 postmenopausal women, 180 microgram MK-7 daily slowed loss of vertebral height and bone mineral density. The EU has authorised vitamin K claims for normal blood coagulation and maintenance of normal bones; cardiovascular outcome evidence remains inconsistent.