- A new randomised trial, VitaK-CAC, found that a daily vitamin K2 supplement (a form called MK-7) modestly slowed the build-up of calcium in the heart’s arteries over two years compared with a placebo.
- The effect was small. Calcium scores still rose in both groups, but they rose less in the people taking vitamin K2. The annual increase was reduced by about 19 points on the standard calcium scoring scale.
- The study was small, with 180 participants, and ran into delays, so the findings are best seen as a promising early signal rather than proof that supplements prevent heart attacks.
- Independent experts urge caution. We do not yet know whether slowing the rise in a calcium score actually translates into fewer heart attacks or strokes, and there is even debate about whether calcified plaque is the dangerous kind.
- Vitamin K can interfere with warfarin and other blood-thinning medications, so nobody on an anticoagulant should start a supplement without speaking to their doctor first.
For years, the question of whether vitamin K supplements can protect the heart has been long on theory and short on evidence. A new clinical trial has now offered the clearest signal yet, and the answer is a carefully qualified “possibly”.
The study, called VitaK-CAC, was published recently in JAMA Cardiology. It found that a daily vitamin K2 supplement slowed the progression of calcium build-up in the coronary arteries over two years. The result is genuinely interesting. It is also a long way from a recommendation that everyone should head to the pharmacy.
What the Study Looked At
Researchers in the Netherlands recruited 180 adults who already had some calcium in their coronary arteries, measured using a CT scan that produces a coronary calcium score. Everyone in the study had a score between 50 and 400, which represents mild to moderate calcification.
Half the group took a daily dose of a vitamin K2 supplement known as MK-7, also called menaquinone-7. The other half took an identical placebo, an inactive tablet with no medicine in it, sometimes called a sugar pill. Neither the participants nor the researchers knew who was taking which until the study ended. This kind of design is the gold standard in medical research, because it stops expectation alone from influencing the result. The participants returned every six months for two years so their calcium scores and vitamin K blood levels could be tracked.
MK-7 is a specific form of vitamin K2. It is favoured in research because the body absorbs it well and it stays in the bloodstream longer than the more common vitamin K1 found in leafy greens.
What They Found
Calcium scores rose in both groups over the two years, which is what usually happens as calcification is a gradual, ongoing process. The difference was in how much they rose.
At the start, the two groups had similar average calcium scores, around 135 and 145. By two years, the placebo group had climbed to 214, while the vitamin K2 group reached 184. The slower climb in the supplement group was statistically significant, meaning it was unlikely to be down to chance alone.
Blood tests confirmed the supplement was doing something measurable. Vitamin K2 levels rose sharply in the treatment group, and a protein involved in keeping calcium out of artery walls behaved differently between the two groups. The researchers calculated that the calcium score and the vitamin K2 treatment were the two strongest predictors of how calcification changed over time.
Why Calcium in the Arteries Matters
Calcium in bones and teeth is essential. In artery walls it is a marker of atherosclerosis, the gradual furring and stiffening of blood vessels that underlies most heart attacks and strokes. The higher the calcium score, the more plaque a person tends to have, and the higher their cardiovascular risk.
The idea behind vitamin K2 is that it activates proteins which help direct calcium towards bones and away from artery walls, the same mechanism we explored in our explainer on vitamins D3 and K2. VitaK-CAC is the first reasonably robust trial to suggest the theory might hold up in the coronary arteries themselves.
A promising early result is not the same as a proven treatment. This trial opens a door. It does not tell us to walk through it just yet.
Why Experts Are Urging Caution
The researchers themselves were measured about their findings, and independent commentators were more cautious still. There are several reasons to hold back.
The first is size and design. With 180 participants and a study that suffered delays, this is a small trial. Small studies can produce real findings, but they need to be repeated in larger groups before anyone can be confident the result is reliable.
The second is more subtle. A calcium score is normally used to measure how much plaque a person has, not as something we actively try to lower. We have strong evidence that a high score predicts higher risk, but very little evidence about what happens when you deliberately slow the score’s rise. Lowering the number is not automatically the same as lowering the danger.
There is even a debate about whether calcified plaque is the dangerous kind. Statins tend to stabilise plaque and can leave behind calcium as a sign of that stability, a counter-intuitive effect we cover in our article on statins and your calcium score. Some experts worry that reducing calcified plaque could leave more of the softer, rupture-prone plaque behind. Nobody yet knows whether that concern is real. The earlier Danish AVADEC trial, which tested vitamin K2 in people with calcified aortic valves, found no significant benefit, underlining how unsettled this field still is.
What This Means for You
If you have had a calcium score done and it showed mild calcification, this study is worth being aware of, but it does not change current advice. The trial’s own authors said they would want larger studies before recommending vitamin K2 in any guideline, and other specialists who reviewed the work agreed they are not yet advising it for their patients.
Vitamin K2 is available without prescription and appears safe for most people at the doses studied. That is partly why some of the researchers said they would not object to people trying it. Safe and available, however, is not the same as proven to prevent heart attacks.
The most important practical point is a safety one. Vitamin K plays a central role in blood clotting, and it directly interferes with warfarin and similar anticoagulant medications. Anyone taking a blood thinner should not start a vitamin K supplement, or make large changes to their intake of vitamin K-rich foods, without first discussing it with their doctor or anticoagulation clinic.
More broadly, what is right for one person is not automatically right for another. Whether a supplement suits you depends on your own health history, the other medicines you take, and any conditions you live with. A supplement that is harmless for one person can interact with medication or be unsuitable for another. Your GP, cardiologist, or pharmacist knows your individual circumstances and is the right person to tell you whether vitamin K2 is sensible, safe, and compatible with the rest of your care.
For everyone, the foundations of heart health have not shifted: not smoking, managing blood pressure and cholesterol, staying active, and understanding your own cardiovascular risk factors. A supplement, even a promising one, sits well behind those.
Heart Matters Resource
When in Doubt, Get Checked Out
A calcium score, a new supplement, or a question about your medications is always worth raising with a professional who knows your history. If you are unsure whether something applies to you, that is reason enough to ask.
Read: When in Doubt, Get Checked Out →Conclusion
VitaK-CAC is a thoughtful, well-conducted small trial that has nudged a long-standing theory a step closer to reality. It suggests that vitamin K2 might slow the build-up of calcium in the coronary arteries, and that finding deserves to be taken seriously and tested further.
For now, the sensible position is curiosity rather than action. If vitamin K2 interests you, the best next step is a conversation with your own cardiologist, GP, or pharmacist, who can tell you whether it is right for you and compatible with any other medicines or conditions you have. The science here is moving, and it is worth watching, but the proven path to a healthier heart still runs through the well-established basics.
Related Reading
- Vitamins D3 and K2: What the Evidence Really Shows
- The Coronary Calcium Score: What It Measures and What to Expect
- Statins and Your Calcium Score: Understanding the Paradox
- A High Calcium Score: What Does It Really Mean?
- Warfarin vs NOACs: Which Blood Thinner Is Right for You?
- Understanding Your Cardiovascular Risk Factors
