The headline result, in plain terms
A two-year randomized trial published in Circulation in 2026 suggests that a high-dose combination of vitamin K2 and vitamin D3 can slow the growth of coronary artery calcification in people who already have a lot of it. The DANCODE trial enrolled 400 adults with severe coronary calcification, defined as a coronary artery calcium (CAC) score of at least 400 Agatston units (AU). They received either K2 plus D3 or a placebo for 24 months, double-blind.
The average CAC score rose by 196 AU in the K2+D3 group and by 248 AU in the placebo group. That is a between-group difference of -52 AU (95% CI, -79 to -24). Relative to the placebo group's progression, that works out to roughly a 21% slowdown.
That is the headline. The caveats matter just as much, and we cover them below.
What the trial actually did
DANCODE was a multicenter, double-blind, placebo-controlled study. Participants were enrolled between February 2023 and February 2024. Key design points:
- Participants: 398 analyzed (30% women), median age 71, median baseline CAC of 903 AU. About 44% had a CAC of 1000 AU or higher.
- Intervention: vitamin K2 at 720 mcg per day plus vitamin D3 at 25 mcg per day (1,000 IU), versus placebo.
- Duration: 24 months, with noncontrast cardiac CT at baseline, 12 months, and 24 months.
- Primary endpoint: change in CAC score at 24 months, analyzed by intention to treat.
- Registration: ClinicalTrials.gov NCT05500443.
The effect was reported as consistent across sex and across the two baseline CAC subgroups (400-999 AU and 1000 AU or higher).
Why CAC progression matters
CAC scoring is a widely used way to quantify calcified plaque in the coronary arteries. Faster progression is linked to a higher risk of cardiovascular events, which is why it is a common surrogate marker in cardiology. Until now, nothing has clearly been shown to slow it apart from managing the underlying risk factors. Statins, for example, are essential for risk reduction, yet they are often associated with increased calcification density as plaque stabilizes.
Vitamin K-dependent proteins, particularly matrix Gla protein, help restrain calcium deposition in vessel walls, and that is the biological rationale for testing K2. DANCODE is a large, well-controlled test of that idea in a population with advanced disease.
The plaque-composition findings
A concern with any therapy that targets calcium is whether it merely shifts plaque into a less stable form. Calcified plaque is generally considered more stable than soft, noncalcified plaque.
To address this, a subset of 143 participants (those with CAC below 1000 AU) also had coronary CT angiography at baseline and 24 months. The results:
- Total plaque volume increased similarly in both groups.
- Noncalcified plaque volume did not differ between groups, so there was no sign of calcium being traded for softer plaque.
- Calcified plaque volume progressed less with K2+D3, with a between-group difference of -8 mm³ (95% CI, -13 to -2).
The authors concluded that the reduced calcification progression was not associated with an increase in noncalcified plaque volume. That is reassuring, but it is a subgroup analysis with a modest sample, and the confidence interval for the plaque-volume difference is fairly wide.
Be honest about what this does not show
The result is promising, but it is easy to overstate. Several limits are worth keeping in view:
- It slowed progression; it did not reverse calcium. Both groups still gained calcium. The K2+D3 group's score rose by 196 AU on average, so the intervention reduced the rate of worsening and did not remove existing deposits.
- No clinical event data. The trial's primary endpoint was an imaging marker. It was not designed or reported to show fewer heart attacks, strokes, revascularizations, or deaths. Whether a 52 AU difference over two years translates into fewer events is unknown.
- A specific, older, high-risk population. The median age was 71 and everyone had severe CAC. The findings may not apply to younger people, those with low or zero calcium, or people with milder disease.
- Two-year follow-up. Longer trials would be needed to see whether the effect persists or grows.
- Combination design. K2 and D3 were given together, so the trial cannot say how much of the effect is due to K2 alone.
Which product was used?
The abstract does not name a commercial product. Trade press coverage from NutraIngredients reported that the K2 used was Balchem's K2VITAL, a menaquinone-7 (MK-7) form. We are relaying that as the trade press reported it, not as something confirmed in the abstract, so check the full paper's methods for the formulation. Results from one form and dose should not be assumed to carry over to other K2 products, particularly lower-dose over-the-counter ones.
Practical takeaways
- The tested dose was 720 mcg of K2 plus 25 mcg (1,000 IU) of D3 daily. That is well above the K2 amounts in many standard multivitamins and supplements.
- Who it may be relevant for: older adults with established, severe coronary calcification, ideally in the context of a cardiology plan. The evidence does not support the idea that people with low calcium scores need this.
- It is not a substitute for standard care. Blood pressure, LDL cholesterol, blood sugar, smoking cessation, and prescribed therapies remain the foundation of cardiovascular prevention.
- Talk to a doctor first if you take warfarin or another vitamin K antagonist. Vitamin K directly affects how these drugs work, and changes in intake can alter anticoagulation. Do not start a high-dose K2 supplement without clinical supervision and INR monitoring.
- Also check with a clinician if you have kidney disease, take other blood thinners, or have other complex conditions.
Bottom line
DANCODE is among the strongest pieces of randomized evidence yet that vitamin K2 plus D3 can modify a hard imaging marker of coronary disease, with a consistent effect across subgroups and no signal of increased soft plaque. But it demonstrates slower calcium accumulation in a high-risk, older cohort, not reversal and not proven clinical benefit. The next questions are whether the effect lasts, whether it reduces actual cardiovascular events, and how much K2 alone contributes. Until then, this is a promising adjunct to discuss with a cardiologist, not a replacement for proven therapy.
Source: Hasific et al., Circulation (2026), PMID 42661461, DOI 10.1161/CIRCULATIONAHA.126.082363.
