Vitamin K2 (MK-7)

Evidence ratingModerate

A menaquinone from fermented foods such as natto. In an RCT giving 244 postmenopausal women MK-7 180 µg/day for 3 years, supplementation was reported to slow bone density loss at the lumbar spine and femoral neck and to limit worsening of carotid arterial stiffness. It activates osteocalcin and matrix Gla protein, directing calcium into bone while limiting vascular deposition.

An ingredient with growing research

Buy

(PR)

View on Amazon View on iHerb

The links below include affiliate links (PR).

Effects reported in research

Slowed bone density loss in postmenopausal women reported in a 3-year RCT

Reported to limit worsening of arterial stiffness

Shown to help direct calcium into bone when combined with vitamin D and calcium

Dosage & timing

Studies commonly use 90–180 µg/day of MK-7.
Its long half-life (~72 hours) makes once-daily dosing stable, and it is often combined with vitamin D3.
One pack of natto (50 g) contains roughly 200–400 µg of K2.

Cautions

•People taking warfarin (an anticoagulant) must consult a doctor or pharmacist, because vitamin K affects its action.
•The same applies to those with medical conditions or on other medications.
•This site is for educational reference only.

Supporting research

Randomized controlled trial

Effects of vitamin K2 (MK-7) supplementation on bone mineral density, bone turnover markers, and arterial calcification: a randomized controlled trial

Osteoporosis International, 2013

An RCT in 244 postmenopausal women receiving MK-7 (menaquinone-7) 180 µg/day for 3 years. Compared with placebo, significant attenuation of lumbar spine and femoral neck bone mineral density decline, with significant increases in carboxylated osteocalcin (active bone protein). Arterial stiffness progression in the carotid artery was also attenuated. The synergistic role with vitamin D is that vitamin D enhances calcium absorption while K2 directs calcium into bone.

View study details

Last checked: 2026-06-25