Vitamin K2 (menaquinone-7, MK-7)

Menaquinone-7 (MK-7) is a long-chain form of vitamin K2. Its side chain has seven isoprene units, which gives it a longer half-life than vitamin K1 (phylloquinone) or MK-4, so it stays in your body longer. Like other vitamin K forms, it acts as a cofactor for the gamma-carboxylation of 'Gla' proteins. Those include osteocalcin (in bone) and matrix Gla protein (in the vascular wall). The dietary sources are limited. By far the richest is natto, a soy food fermented with Bacillus subtilis, with smaller amounts in cheese and fermented dairy. In a 3-year RCT in 244 postmenopausal women, 180 micrograms of MK-7 a day slowed the loss of vertebral height and bone density. The EU has authorized vitamin K claims for normal blood clotting and for maintaining normal bones. But the cardiovascular outcome evidence is still inconsistent.

Last reviewed: June 22, 2026

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