Vitamin K2 and Arterial Stiffness: A 3-Year Trial
The finding: Three years of 180 mcg of vitamin K2 as MK-7 significantly improved arterial stiffness in healthy postmenopausal women, with the largest gains in those whose arteries were stiffest to begin with.
What they did
244 healthy postmenopausal women were randomly allocated to either 180 mcg a day of MK-7 (menaquinone-7) or a matching placebo, and followed for three years. Neither the women nor the researchers knew who was taking which.
Arterial stiffness was measured properly rather than inferred. Local carotid stiffness was assessed by echotracking, and regional aortic stiffness by pulse wave velocity using mechanotransducers. They also tracked dephosphorylated uncarboxylated matrix Gla-protein, a marker that rises when vitamin K is in short supply.
Three years is the headline strength of this trial. Arteries change slowly, and most supplement studies are far too short to detect anything at all.
What they found
- Carotid-femoral pulse wave velocity and the Stiffness Index both decreased significantly across the whole MK-7 group.
- In women whose baseline Stiffness Index was above the median of 10.8, more measures improved again: distension, compliance, distensibility, Young's Modulus and local carotid pulse wave velocity.
- MK-7 reduced dephosphorylated uncarboxylated matrix Gla-protein by 50% compared with placebo.
That 50% drop in the vitamin K status marker is the detail that makes the rest credible. It confirms the dose genuinely changed vitamin K biology in the body, so the arterial changes have a traceable mechanism behind them rather than being a lucky measurement.
What this means for you
The dose and form are specific: 180 mcg a day of MK-7. MK-7 stays in the bloodstream far longer than MK-4, which is why it is the form used in long trials and the form worth looking for on a label. A multivitamin carrying a token amount of K1 is not the same thing.
Timeframe is the real lesson. This was a three-year trial and the measurements needed that long. If arterial health is the goal, this is a years-long proposition, which is an argument for picking something you will actually keep taking.
Vitamin K2 is also commonly paired with vitamin D3, because the two work together in directing calcium, and most D3 products you will see now include it.
Important safety note: vitamin K interacts directly with warfarin and other vitamin K antagonist blood thinners. If you take one of those, do not add a vitamin K supplement without talking to your doctor first. This is one of the genuinely significant supplement and medication interactions.
The study
Knapen MH, Braam LA, Drummen NE, Bekers O, Hoeks AP, Vermeer C. Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women: a double-blind randomised clinical trial. Thrombosis and Haemostasis. 2015 May;113(5):1135-1144.
General information only. This is a summary of published research, not a therapeutic claim and not medical advice. A result found in a trial population is not the same as a product doing that for you. Always read the label and follow the directions for use. If you have a health condition or take medication, check with your health practitioner before use.
