Vitamin K2 and coronary calcium: promising evidence, but no proven clinical benefit

K1 versus K2: the difference

Vitamin K comes in two main dietary forms. Both are used by the body to activate vitamin-K-dependent proteins.

They differ mainly in their food sources, how long they remain in the circulation, and the evidence behind them. Their functions do not divide neatly into “clotting” and “arteries”.

MK-4 and MK-7

Vitamin K2 includes several menaquinones.

MK-4 is found in meat, egg yolk and liver. MK-7 is found mainly in fermented foods such as natto. MK-7 has a longer half-life and remains in the circulation longer after a dose.

Trials have studied K1, MK-4 and MK-7. MK-7 was the form used in the 2026 coronary-calcium trial.

Where coronary calcium comes from

Coronary calcification is not usually the starting point of artery disease.

Atherosclerosis begins when apoB-containing particles, including LDL, enter and become retained in the artery wall. This triggers inflammation. Immune cells enter the plaque, lipid accumulates, and the vessel wall is repeatedly injured and repaired.

Over time, established plaque may develop fibrosis and calcium deposits. Calcification is therefore often a sign of previous and ongoing plaque biology. It is not simply dietary calcium settling in an otherwise normal artery.

This distinction matters. Removing or slowing calcium alone would not remove the retained cholesterol, inflammatory activity or plaque that drove the calcification in the first place.

Where K2 might act

Vascular calcification is an active and regulated biological process.

Matrix Gla protein (MGP) is produced within the vessel wall and helps inhibit inappropriate mineralisation. Vitamin K is required to carboxylate and activate MGP.

This gives K2 a genuinely plausible mechanism. Better activation of MGP may influence how calcification develops within an established plaque — and it is a real, regulated pathway, not a marketing story.

But K2 acts on one downstream step. It does not lower LDL or apoB, and it has not been shown to reverse established atherosclerosis.

Warfarin provides an important clue. It blocks vitamin K recycling, and long-term use has been associated with more vascular calcification. This supports the biological link between vitamin K and calcification. It does not prove that K2 supplementation prevents cardiovascular events.

What population studies show

Large observational studies have linked higher dietary K2 intake with better cardiovascular outcomes.

• The Rotterdam Study followed about 4,800 Dutch adults for around 10 years. Higher K2 intake was associated with lower coronary heart disease mortality and less severe aortic calcification. K1 showed no clear association.
• The Prospect-EPIC cohort found that each additional 10 micrograms of K2 per day was associated with about a 9% lower risk of coronary heart disease.

These are associations, not proof.

People who eat more K2-rich foods may differ in many other ways. Diet, socioeconomic factors, smoking, exercise and other health behaviours may partly explain the findings. The Rotterdam data are also more than two decades old.

Randomised trial evidence therefore matters more.

The 2026 trial

In June 2026, JAMA Cardiology published the first randomised trial of stand-alone MK-7 supplementation using coronary calcium progression as the primary endpoint.

VitaK-CAC included:

• About 180 adults with symptomatic but generally mild coronary artery disease.
• Baseline coronary calcium scores of 50–400.
• MK-7 at 360 micrograms daily, or placebo.
• Two years of treatment.

Coronary calcium increased in both groups.

Scores rose from about 135 to 184 with MK-7 and from about 145 to 214 with placebo. The difference was statistically significant. The adjusted analysis estimated approximately 19 fewer Agatston units of annual progression with MK-7.

This shows a measurable biological effect. It does not establish a clinical benefit.

Important limitations:

• The trial was small.
• It was not designed to detect differences in heart attacks, stroke or death.
• Adherence was imperfect and some participants did not complete follow-up.
• There was no clear difference in stenosis severity or the number of affected vessels.
• The proportion of fast calcium progressors was not significantly different.
• The accompanying editorial concluded that routine widespread use could not yet be recommended.

The study supplement was supplied by its manufacturer. The manufacturer reportedly had no role in the study design, analysis or publication. The main funding came from the Dutch Heart Foundation.

Why less calcium is not automatically better

This is the most important limitation when interpreting the trial.

A higher coronary calcium score usually means a greater total burden of coronary atherosclerosis. This is why calcium scoring is valuable for cardiovascular risk assessment.

However, calcium is only one component of plaque. Its meaning also depends on its pattern and density.

Tiny areas of microcalcification may occur within active, inflamed plaque. Larger and denser areas of calcification often develop later, alongside fibrosis and healing. Dense calcification can be a feature of more stable plaque.

Statins illustrate this apparent paradox.

Statins reduce LDL, reduce cardiovascular events and make plaques less lipid-rich and more stable. At the same time, treated plaques may become more densely calcified, and the calcium score may continue to rise.

This does not mean statins are making the disease more dangerous. It may reflect a shift from softer, lipid-rich plaque towards a more fibrotic and densely calcified plaque phenotype.

Therefore, a slower-rising calcium score cannot automatically be interpreted as fewer heart attacks. It may be favourable. It may be neutral. Only a trial measuring clinical events can answer that question.

No such outcome trial has yet been completed for K2.

Treat the cause, not only the calcium

The major drivers of coronary atherosclerosis remain:

• Prolonged exposure to LDL and other apoB-containing particles.
• Smoking.
• High blood pressure.
• Diabetes and insulin resistance.
• Chronic kidney disease.
• Age, genetics and other risk factors.

These factors promote plaque formation before calcium becomes visible.

The treatments with proven cardiovascular benefit address these upstream risks. They include LDL lowering, blood-pressure control, smoking cessation, diabetes management, physical activity and an appropriate dietary pattern.

K2 should not distract from these treatments. Even if it influences calcification, it has not been shown to treat the underlying atherosclerotic process.

Is it safe? Warfarin and other cautions

K2 was well tolerated in VitaK-CAC. No important safety signal emerged.

However, the trial was too small to identify uncommon adverse effects or establish long-term safety.

If you have advanced kidney disease or receive dialysis, discuss supplements with your specialist first. Vascular calcification in chronic kidney disease is complex and may involve different mechanisms.

Foods that contain K2

These foods contain K2. This is a list of sources, not a set of cardiovascular recommendations.

Food first is reasonable for most people.

If a supplement is used, MK-7 is a common form in clinical studies. The best dose for cardiovascular prevention is not established.

Common questions

Last medically reviewed: July 2026. This article is general information, not personal medical advice. Discuss your own situation, medications and supplements with your own doctor.

Related: Coronary calcium risk calculator · What is a coronary calcium score?