Limited evidenceHeart & metabolic

Vitamin K2 (MK-7)

MK-7 reliably improves vitamin K biomarkers — it carboxylates osteocalcin and matrix Gla protein exactly as advertised. But the hard-outcome evidence is thin, and the best-powered trial of the vascular calcification claim was completely flat. Good mechanism, unproven benefit.

What the science says

Slows age-related bone loss in postmenopausal women Moderate evidence
In the largest MK-7 bone trial, 244 healthy postmenopausal women took 180 mcg/day or placebo for three years. MK-7 significantly reduced the age-related decline in bone mineral content and BMD at the lumbar spine and femoral neck (but not total hip) and reduced loss of vertebral height in the lower thoracic region. Fractures were not an endpoint, and this remains one trial in one population.
Did not slow vascular calcification in the trial built to test it Limited evidence
The AVADEC trial gave 720 mcg/day MK-7 plus 25 mcg vitamin D to 365 elderly men with aortic valve calcification scores above 300 AU for two years. Despite a large fall in dephospho-uncarboxylated MGP (-212 pmol/L), progression of aortic valve calcification was identical (mean difference 17 AU, 95% CI -86 to 53, P=0.64), as were aortic valve area (P=0.78) and peak jet velocity (P=0.21). The biomarker moved; the artery did not.
Modest improvement in arterial stiffness — a surrogate endpoint Limited evidence
In the same three-year cohort of 244 postmenopausal women, 180 mcg/day MK-7 significantly reduced the stiffness index beta versus placebo, with the effect concentrated in women who started with high arterial stiffness. This is a single trial measuring a surrogate, and the calcification trial above failed to corroborate the underlying story.

Dosage & safety

Studied doseTrials used 180 mcg/day of MK-7 for bone and arterial stiffness over three years, and 360-720 mcg/day in vascular calcification trials. MK-7 has a serum half-life of roughly three days versus hours for K1 and MK-4, so once-daily dosing is adequate. Do not confuse it with MK-4: the Japanese osteoporosis trials used menatetrenone at 45 mg/day, a 250-fold higher, prescription-only dose that is not interchangeable with MK-7.

SafetyWell tolerated at 180-720 mcg/day in trials lasting up to three years, with no toxicity signal and no established upper limit. The warfarin caveat applies more forcefully than for K1: MK-7's long half-life makes INR harder to re-stabilise after a change, so treat it as effectively contraindicated on warfarin, acenocoumarol or phenprocoumon unless a clinician is actively managing the dose. No interaction with DOACs. Check that a product specifies all-trans MK-7 — cis isomers are biologically inactive, and cheap synthetic products can contain a large inactive fraction with no way for the buyer to tell.

Scientific references

Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women
Knapen MH, Drummen NE, Smit E, Vermeer C, Theuwissen E — Osteoporosis International, 2013
Vitamin K2 and D in Patients With Aortic Valve Calcification: A Randomized Double-Blinded Clinical Trial
Diederichsen ACP, Lindholt JS, Möller S, et al. — Circulation, 2022
Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women. A double-blind randomised clinical trial
Knapen MH, Braam LA, Drummen NE, et al. — Thrombosis and Haemostasis, 2015

Where to buy

Doctor's Best, Natural Vitamin K2 MK-7, 100 mcg, 60 Veggie Caps

View on iHerb

Referral link — this site may earn a commission on purchases.

Related in Heart & metabolic

Vitamin B3 (Niacin) Limited evidence
Chromium Limited evidence
Potassium Strong evidence
Vanadium Limited evidence
L-Arginine Moderate evidence
Taurine Moderate evidence