Vitamin K2

The most mechanistically compelling cardiovascular hypothesis in supplement medicine — and what happened when it was put to the test.

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These articles provide education to enhance your healthcare partnership. All treatment decisions should involve your healthcare team. Use this knowledge to have informed discussions, not to replace medical care.

In brief: Vitamin K2 activates the proteins that keep calcium in bone and out of artery walls — a mechanism that is real, well understood, and supported by population studies linking higher K2 intake to lower cardiovascular risk. (1,2,5) Randomized trials confirm that K2 supplements switch this pathway on. (3) But the best randomized test to date — Diederichsen 2022 in Circulation — found that this biochemical activation did not slow aortic valve calcification, and an earlier trial in people with diabetes found no effect on vascular calcification either. (7,8) No trial has tested whether K2 supplementation prevents heart attacks, strokes, or cardiovascular death. The biology is strong; the clinical evidence has not yet confirmed it.

Introduction

For years, vitamin K2 looked like one of the most promising supplements cardiovascular research had identified. The mechanism was specific. The molecular target was known. The biochemistry activated predictably when the supplement was taken. (3,5) Two large independent population studies showed the cardiovascular protection the biology predicted — and only for K2, not for K1. (1,2) On paper, K2 looked like a clean translation from biology to clinical benefit.

The randomized trials told a more complicated story.

Vitamin K2 does not remove calcium from arteries. It determines where calcium goes. The body requires calcium for bone formation but must simultaneously prevent it from depositing in arterial walls. That balance depends on proteins that direct calcium to the right places, and those proteins require vitamin K2 for activation. (5) When K2 is insufficient, the regulatory proteins remain inactive, arterial calcification proceeds unchecked, and bone formation is impaired at the same time — both problems from a single nutritional shortfall.

The most direct randomized test of the hypothesis — Diederichsen 2022 in Circulation, conducted in a population with active calcium deposition exactly where the mechanism should produce benefit — found no effect on calcification progression. (8) The biology earned K2 a place in the evidence discussion. The outcome data that would earn it a place in a treatment plan does not exist.

Find Your Situation

The table identifies what the evidence shows for specific clinical profiles. K2 has no cardiovascular outcome-trial data in any of these situations, so none carries a proven outcome benefit; what changes from row to row is the balance of biological plausibility against the relevant cautions. Each entry is examined in full in the sections that follow.

Where the Evidence Stands

K2 is unusual in this series: it passes nearly every test that matters, except the one most important for a treatment claim.

Mechanism and biochemical activation: established and confirmed. The calcification biology is well characterized, and K2 supplementation consistently reduces uncarboxylated matrix Gla protein, the marker that the target pathway is being activated. (3,5)

Surrogate endpoints: mixed. One randomized trial found less arterial-stiffness progression with MK-7 (Knapen 2015). (3) Two randomized trials found no slowing of calcification progression (Zwakenberg 2019; Diederichsen 2022). (7,8)

Cardiovascular outcome trials: none. No randomized trial has tested whether K2 reduces heart attacks, strokes, or cardiovascular death.

Caution: warfarin. K2 opposes the action of warfarin and other vitamin K antagonists.

Taken together, the evidence supports a biomarker effect on the calcification pathway but has not shown that K2 reduces cardiovascular events, and it carries a warfarin caution. It is information to bring to a clinician, not a basis for self-directed treatment.

Vitamin K1 and Vitamin K2: The Distinction That Matters

Vitamin K is not one molecule. It is a family of related compounds with different sources, different tissue distributions, and different clinical roles.

Vitamin K1 (phylloquinone) is found in green leafy vegetables — kale, spinach, broccoli, Brussels sprouts — and is the predominant form in Western diets. It goes primarily to the liver, where it activates the proteins that make blood clot normally. Most people with reasonable vegetable intake have adequate K1 for this purpose.

Vitamin K2 (menaquinones) reaches bone, arterial walls, and other peripheral tissues far more effectively than K1. The two most studied forms are MK-4, found in meat, eggs, and dairy, with a half-life of only a few hours; and MK-7, found in fermented foods, particularly natto, with a half-life of several days that produces more stable blood levels and better tissue accumulation. Most K2 cardiovascular research uses MK-7. (9)

The key differences are summarized below. (5,9,10)

The critical point: adequate K1 intake does not ensure adequate K2 in peripheral tissues. K1 handles clotting and liver-based functions; K2 is the form that reaches the arterial walls and bone where the calcification-regulating proteins operate. (5) Most Americans get adequate K1 from green vegetables, but most do not consume meaningful K2 unless they regularly eat fermented soybeans (natto), aged hard cheeses, or other fermented foods. This is why population studies consistently find that K2 intake — not K1 — associates with cardiovascular outcomes. (1,2) Eating more salad does not address the K2 gap.

The Calcium Paradox

In aging populations, calcium does two opposite things at once: it leaves bone, contributing to osteoporosis, and it accumulates in arteries, contributing to vascular stiffness and cardiovascular disease. The same person can be losing bone calcium and depositing arterial calcium at the same time.

Both processes depend on K2-activated proteins. Osteocalcin, in bone, and matrix Gla protein (MGP), in arterial walls, are both vitamin K-dependent. When K2 is insufficient, both remain inactive: calcium is not adequately incorporated into bone and is not adequately blocked from depositing in arteries. (5)

Whether supplementing K2 resolves the paradox in clinical terms — fewer fractures, less arterial calcification, fewer cardiovascular events — is the question that observational data raise but randomized trials have not yet confirmed.

The Biology of Arterial Calcification

For most of the twentieth century, arterial calcification was understood as a passive, degenerative consequence of aging — calcium accumulating in damaged arteries the way scale builds up in old pipes. That view was overturned in the 1990s. The publication of matrix Gla protein knockout-mouse data in Nature in 1997 — mice lacking a single protein died within weeks from rapid, extensive arterial calcification — showed that the arterial wall is not a passive recipient of calcium but an active participant in preventing it. (4) Together with the identification of K2 as the cofactor required to activate MGP, that finding reframed vascular calcification as a regulated process that might be preventable at the molecular level, and it is the source of the scientific interest in the K2 hypothesis.

Arterial calcification is therefore not simply a marker of age. It is an active, regulated process that contributes independently to cardiovascular risk. Calcium-phosphate deposits form in arterial walls, particularly within atherosclerotic plaques. These deposits stiffen arteries, raise pulse wave velocity — the speed at which each heartbeat’s pressure wave travels through the arterial system, a measure of vessel stiffness — and elevate systolic blood pressure. Coronary artery calcification, measured by the CAC score on CT imaging, predicts cardiovascular events independently of traditional risk factors.

One important nuance: not all arterial calcification carries equal risk. Small, spotty microcalcification within lipid-rich plaques may increase the risk of acute plaque rupture by concentrating mechanical stress at the plaque surface. Dense, organized calcification, by contrast, may represent a more stable state — mineralized, less prone to sudden rupture, and at a given calcification volume associated with lower event risk rather than higher. (11) The CAC score measures total calcification burden, not the type or vulnerability of individual deposits.

This complexity appears elsewhere in cardiovascular medicine and is worth naming. Statin therapy can increase coronary calcification density while reducing cardiovascular events. (12) That apparent paradox resolves once the biology is understood: the calcification statins drive appears to be the dense, stabilizing kind, replacing more dangerous microcalcification within active plaques. “Less calcification” is therefore not always straightforwardly better — the clinical meaning depends on the stage, location, and character of the deposits.

The cellular mechanism of arterial calcification resembles bone formation in the wrong place. Smooth muscle cells in arterial walls can transform into osteoblast-like cells — the same cell type that builds bone — and actively deposit calcium matrix, a transformation driven by inflammation, elevated phosphate, and a deficiency of calcification inhibitors. (5)

Matrix Gla protein is the most potent known inhibitor of this process. Synthesized in vascular smooth muscle cells, MGP physically binds calcium crystals and blocks further mineral deposition — but only after it has been activated by vitamin K2 through a chemical modification called carboxylation. Without sufficient K2, MGP remains in its uncarboxylated, inactive form and cannot prevent calcification. (5)

Circulating uncarboxylated MGP — the inactive form, measurable in blood — reflects K2 status in peripheral tissues, and higher levels associate with more arterial calcification and greater cardiovascular risk in observational studies. (1,2) K2 supplementation consistently reduces uncarboxylated MGP, confirming the pathway is being activated. (3,5) Whether that activation translates into measurable clinical benefit is the question the trials were designed to answer.

The Clinical Evidence

Observational Data: Consistent and Mechanistically Coherent

Population studies consistently associate higher K2 intake with better cardiovascular outcomes — and specifically K2, not K1, which is the pattern the MGP mechanism predicts.

The Rotterdam Study followed 4,807 Dutch adults aged 55 and older for about seven years. Those in the highest tertile of K2 intake had roughly 57% lower risk of dying from coronary heart disease and about 41% lower risk of incident coronary heart disease compared with the lowest tertile; all-cause mortality and severe aortic calcification were lower as well. K1 intake showed no association with any of these outcomes. (1)

The PROSPECT (Prospect-EPIC) cohort followed 16,057 Dutch women aged 49 to 70 for approximately eight years. Each 10 µg increase in daily K2 intake was associated with a 9% reduction in coronary heart disease risk. K1 again showed no association. (2)

The consistency of this pattern — K2 protective, K1 neutral — across two independent cohorts is what the MGP mechanism predicts, because K2 is the form that reaches arterial walls. The associations are real and mechanistically coherent.

The limitation also holds. People who consume more K2 — from fermented foods, quality dairy, and eggs — may differ from lower-K2 consumers in many dietary and lifestyle dimensions that independently affect cardiovascular risk. Dietary K2 may function partly as a marker of a broader eating pattern rather than as an isolated nutrient effect. Supplement trials isolate a single compound from that context, and the effect of the food pattern is not the same as the effect of the isolated compound, even when the compound is biologically active.

Arterial Stiffness: A Positive Randomized Signal

The Knapen 2015 trial randomized 244 healthy postmenopausal women to MK-7 (180 µg daily) or placebo for three years. (3) The K2 group showed significantly less progression of arterial stiffness measured by carotid-femoral pulse wave velocity, with the largest improvement in women who had stiffer arteries at baseline. Uncarboxylated MGP fell substantially in the treatment group, confirming biochemical activation.

This is a meaningful result. Arterial stiffness is a real cardiovascular risk marker — stiff arteries increase cardiac workload, raise pulse pressure, and accelerate both coronary disease and heart failure. Slowing its progression is clinically relevant, though it remains a surrogate endpoint, not a hard outcome like heart attack or stroke.

K2 and Vascular Biology Beyond Calcification

Vascular disease is not simply pipes filling with calcium. It is a dynamic remodeling process involving endothelial dysfunction (failure of the artery’s inner lining), chronic inflammation, breakdown of the structural matrix, transformation of muscle cells into bone-like cells, and progressive loss of arterial compliance — the elastic give that lets arteries expand and recoil with each heartbeat. MGP is active throughout the arterial wall, and its activation may influence wall properties beyond the formation of discrete calcium deposits. (5) The Knapen 2015 reduction in pulse wave velocity is consistent with K2 influencing the elastic properties of arterial tissue, not merely blocking calcium. (3) Whether that reflects reversal of early calcification, preservation of smooth-muscle-cell phenotype, or something broader at the matrix level is not resolved. The Rotterdam Study’s strongest K2 association was with cardiovascular mortality specifically — more consistent with broad vascular protection than with calcification alone. (1)

This broader biology makes K2 one of the more scientifically interesting supplements in this series, even as the randomized evidence on clinical endpoints has disappointed.

Calcification Progression: The Key Trials Were Negative

The most direct test of the calcification hypothesis is Diederichsen 2022, a double-blind randomized trial in Circulation. It enrolled community-dwelling men aged 65 to 74 with documented aortic valve calcification (an AVC score of at least 300, above the 90th percentile) — a population with active, ongoing calcium deposition, exactly where K2’s mechanism should produce benefit. Participants received MK-7 (720 µg) plus vitamin D (25 µg) or placebo for 24 months, with serial CT imaging. Patients on vitamin K antagonists were excluded.

K2 plus vitamin D did not slow aortic valve calcification progression — the trial’s primary endpoint — compared with placebo. (8) This is the highest-quality randomized trial directly testing the core cardiovascular claim for K2, and it was negative on the outcome it was designed to measure.

The same trial reported one finding that keeps the question open: a secondary analysis suggested possibly slower progression of coronary artery calcification in the treatment group. The investigators presented this as hypothesis-generating and explicitly called for confirmation, and it does not change the negative primary result — but it is part of an honest reading of the trial. (8)

An earlier randomized trial, Zwakenberg 2019, studied 68 men and women with type 2 diabetes and established cardiovascular disease, randomized to MK-7 (360 µg daily) or placebo for six months, with vascular calcification assessed by CT and by ¹⁸F-sodium-fluoride PET. It found no benefit on arterial calcification. (7)

The randomized trials converge: K2 supplementation consistently reduces uncarboxylated MGP — the pathway is being activated — but this has not translated into measurable slowing of calcification in any trial designed to detect it. Understanding why requires looking at what established calcification actually is. Once calcium-phosphate has organized into crystalline hydroxyapatite — the same mineral that forms bone, hard and stable — it is not soft tissue that can be dissolved by reactivating an inhibitory protein. MGP prevents calcium from depositing; there is no established mechanism by which reactivating MGP dissolves mineral that has already been laid down. The patients in these trials had documented, existing calcification, meaning the process K2 might prevent had already occurred. Whether K2 could slow calcification in people with early or no established disease, where prevention rather than reversal is the question, has not been tested.

Why the Research Continues

The negative trials have not ended scientific interest in K2, for reasons worth stating plainly. The trials enrolled people with established calcification — arguably the wrong target for a preventive mechanism. Cardiovascular calcification develops over decades; the trials ran six to twenty-four months. The endpoint was calcification volume, which may not capture the clinically relevant change — a shift from unstable microcalcification toward denser, more stable deposits could represent benefit without volume reduction. (11) The arterial-stiffness signal from Knapen 2015 has not been explained away by the negative calcification data; something measurably changed in the arterial wall with MK-7, and whether that translates into long-term protection has not been tested. (3) The K2 hypothesis is unresolved, which is not the same as refuted.

Bone Health: The Same Pattern

K2’s bone effects follow an identical pattern. The carboxylation mechanism that activates MGP in arteries also activates osteocalcin, the protein that incorporates calcium into bone, and undercarboxylated osteocalcin associates with fracture risk in observational studies.

The Binkley 2009 trial randomized 381 healthy postmenopausal North American women to K1 (1 mg daily), MK-4 (45 mg daily), or placebo — all with calcium and vitamin D — for 12 months. Both K forms reduced undercarboxylated osteocalcin (biochemical activation confirmed) but neither altered bone turnover markers, bone mineral density, or bone geometry. (6) Biochemical activation without measurable clinical effect: the parallel to the calcification trials is exact.

MK-4 at 45 mg daily is approved for osteoporosis in Japan, where it has been studied extensively at that dose. That protocol functions more like pharmacologic therapy than nutritional replacement — the dose is roughly a thousand times higher than typical dietary intake. MK-7 at 100 to 200 µg daily, the typical Western supplement, is a different form at a dose more than 200 times lower than the Japanese protocol, and outcome data at supplement-relevant doses in non-Japanese populations are limited.

The Evidence at a Glance

The pattern is consistent. K2 activates the biochemical pathway the mechanism predicts. It produced a positive arterial-stiffness signal in Knapen 2015. It has not slowed established calcification in the trials designed to detect that effect. No randomized trial has tested whether it reduces hard cardiovascular outcomes. The empty bottom row is structurally important: it identifies what is missing, not just what was tried.

Vitamin K2 and Cardiovascular Guidelines

No major cardiovascular or bone-health guideline recommends vitamin K2 supplementation.

The 2018 ACC/AHA cholesterol guideline, the 2017 ACC/AHA hypertension guideline, the 2022 AHA/ACC/HFSA heart failure guideline, and the major osteoporosis guidance from bodies such as the Bone Health and Osteoporosis Foundation and the Endocrine Society do not include K2 as recommended therapy for cardiovascular prevention or for osteoporosis in non-Japanese populations.

What this means: K2 has been mechanistically interesting for decades, the observational data are consistent, and the supplement is widely available and inexpensive. If the trial evidence supported routine use, the guidelines would reflect it. They do not, because the trials have not delivered the outcomes the mechanism predicted.

Dosing, Product Quality, and the Warfarin Interaction

Form and Dose

MK-7 is the form most studied for cardiovascular purposes, typically dosed at 100 to 200 µg daily. Its half-life of roughly three days allows once-daily dosing with stable blood levels, substantially longer than MK-4’s half-life of a few hours. (9) The Knapen 2015 trial used 180 µg; Diederichsen 2022 used 720 µg. (3,8) MK-4 requires much higher doses to produce measurable effects and is a different pharmacological entity from the typical Western MK-7 supplement.

K2 is fat-soluble, so absorption with a fat-containing meal is substantially better than on an empty stomach. (9)

Dietary Sources

Approximate K2 content per typical serving, from published food-composition analyses. (10)

Natto is by far the richest source but presents palatability challenges for most Western consumers. Reaching 100 µg daily through diet outside natto consumption is difficult, which supports a plausible nutritional rationale for supplementation in people who do not eat fermented soybeans regularly.

The Vitamin D Relationship

Vitamin D increases intestinal calcium absorption; K2 helps direct that calcium toward bone and away from arteries. The combination is physiologically rational, particularly at higher vitamin D doses. But Diederichsen 2022 specifically tested K2 plus vitamin D and found no benefit on calcification progression, so the pairing, while theoretically coherent, does not have positive outcome-trial support. (8) Article 15 covers vitamin D in full.

The Warfarin Interaction

Vitamin K — including K2 — directly opposes warfarin’s mechanism. Warfarin blocks the recycling of vitamin K to prevent clotting-factor activation; K2 supplementation can override that effect, lowering the INR and increasing clot risk. Even relatively small changes in vitamin K intake can destabilize previously stable warfarin dosing in some individuals, which is why warfarin patients are generally counseled to keep their vitamin K intake consistent rather than to avoid it entirely. This is a pharmacologically significant interaction that a prescriber managing warfarin would need to know about before K2 is added to any regimen. Article 20 covers cardiovascular drug-supplement interactions in full.

Direct oral anticoagulants (apixaban, rivaroxaban, dabigatran, edoxaban) do not work through vitamin K and are not affected by K2 supplementation.

Two Patients, Same Supplement Aisle, Different Answers

Both profiles below are composites built from the populations studied in the trials this article reviews.

Patient A: A 63-year-old postmenopausal woman with osteopenia on DXA scanning, on no anticoagulant, who eats no fermented foods and rarely eats aged cheese or eggs. She takes vitamin D and calcium and asks whether K2 would add anything.

She matches the population in whom K2’s nutritional rationale is most coherent: a plausible dietary gap (low K2 intake) and an area where the biology connects to her actual concern (bone and calcium handling). MK-7 at 100 to 200 µg, taken with a fat-containing meal, is the most studied formulation and the form used in the positive arterial-stiffness trial. (3,9) But the realistic expectation the evidence supports is correction of a nutritional gap with biological plausibility — not proven fracture reduction and not confirmed cardiovascular event prevention, neither of which has been demonstrated for K2. The Binkley 2009 trial, in a directly comparable population, showed biochemical activation without measurable change in bone density, so the clinical benefit at supplement doses remains uncertain. (6) K2 is not a treatment for her osteopenia or her cardiovascular risk. Whether it has a place in her regimen is a question her physician is positioned to weigh with her full clinical picture; the risk profile is low in the absence of anticoagulation, but the case rests on plausibility, not proven benefit.

Patient B: A 71-year-old man with a CAC score of 480 — severe coronary artery calcification — on atorvastatin, aspirin, and a beta-blocker. He has read that K2 dissolves arterial calcium and asks whether it would reduce his score.

He has established, documented, severe coronary calcification, and the evidence does not support K2 as a way to reverse or slow calcification that is already present. Diederichsen 2022, in a population with active calcification and a higher K2 dose than typical supplements, was negative on its primary endpoint; Zwakenberg 2019, in patients with diabetes and vascular calcification, was also negative. (7,8) His medications — a statin, aspirin, a beta-blocker — carry cardiovascular outcome evidence that K2 does not. The prescriber managing his regimen has the clinical context to discuss whether K2 has any role, but nothing in the evidence suggests it will lower his score or substitute for the therapies already in place.

Common Misconceptions

“Vitamin K2 dissolves arterial calcification.” K2 activates MGP, a protein that inhibits further calcification. Established calcification, visible as a CAC score, has not been shown to reverse or decrease with K2 in any randomized trial. (7,8) The mechanism is preventive in principle, not reparative.

“Vitamin K1 from leafy greens gives me the same protection.” It does not. The cardiovascular observational signal is specific to K2 and absent for K1 across two independent large cohorts — exactly the pattern the tissue distribution predicts. (1,2,5)

“Consistent observational associations are enough to justify supplementing.” That assumption has failed repeatedly in this field: niacin (Article 8), antioxidant vitamins (Article 17), homocysteine-lowering B vitamins (Article 16), and now K2 on calcification progression. (7,8) Biomarker improvement does not reliably translate into event reduction, even when the biomarker is mechanistically central and the improvement is biochemically real. Dietary K2 also comes embedded in a broader food pattern; a supplement provides an isolated compound. The two are not equivalent.

“K2 is approved for osteoporosis, so it must work.” MK-4 at 45 mg daily is approved in Japan based on Japanese data at a pharmacological dose. MK-7 at 100 to 200 µg, the typical Western supplement, is a different form at a dose more than 200 times lower. The Binkley 2009 trial of MK-4 in postmenopausal North American women activated osteocalcin biochemically but produced no measurable change in bone density or geometry. (6) The Japanese approval does not transfer to Western supplement doses.

“Higher K2 doses will produce better results.” Diederichsen 2022 used 720 µg MK-7, well above the typical 100 to 200 µg, and found no benefit on calcification progression. (8) More uncarboxylated MGP is converted to its active form at higher doses, but in the trials conducted to date this has not produced better clinical outcomes.

“K2 must be safe because it’s a vitamin.” Vitamin K, including K2, opposes warfarin’s mechanism. In someone on warfarin, K2 supplementation can lower the INR and increase clot risk. The classification as a vitamin does not change the pharmacological interaction.

The Bottom Line

Vitamin K2 has the most mechanistically compelling cardiovascular hypothesis of any supplement in this series. K2 activates the proteins that keep calcium out of arterial walls, and the discovery that MGP controls this process changed how cardiovascular researchers think about calcification. (4,5) The observational signal shows exactly the specificity the mechanism predicts. (1,2) The biochemical evidence confirms the pathway activates when K2 is supplemented. (3) None of that has translated into measurable clinical benefit in the trials designed to test it. (7,8)

The biology of the target explains why Diederichsen 2022 may not be the last word. Established calcification is organized crystalline mineral, not soft tissue, and the trials tested the harder question — slowing or reversing disease that had already formed — in populations where the process had already occurred. Whether K2 could slow calcification over decades in people who do not yet have established disease has not been tested. Researchers who built this hypothesis have reasonable grounds to keep working on it.

Across this series, supplements have failed in three structurally different ways: biology untested at scale, biology tested and disproven, and biology that works but cannot be reliably delivered. K2 is something else — biology tested in the right populations at the right doses, with negative trials, and a target whose physical nature leaves open whether those trials asked the right question. K2 may prove to be a preventive nutrient whose effects are too slow or too early in the disease process for current trials to capture, or it may join the longer list of mechanisms that improve a measurement without changing outcomes. The current evidence does not distinguish between those two possibilities.

Article 15 examines vitamin D — the most studied nutrient of the past two decades, with the largest observational evidence base in the field, and one of the clearest demonstrations that observational associations do not always survive randomized testing.

Key Terms

Arterial calcification: Deposition of calcium in arterial walls, contributing to stiffness, elevated systolic blood pressure, and independently predicting cardiovascular events. Not a passive aging process — it is actively regulated by inhibitory proteins including MGP.

Calcium paradox: The observation that calcium simultaneously leaves bone (osteoporosis) and accumulates in arteries in aging populations, potentially reflecting inadequate K2-dependent activation of calcium-regulating proteins in both locations at once.

Carboxylation: The chemical modification, enabled by vitamin K, that converts proteins such as MGP and osteocalcin from inactive to active form. Without sufficient K2, these proteins remain uncarboxylated and cannot perform their calcium-regulating functions.

CAC score (coronary artery calcium score): A CT-based measure of calcification in the coronary arteries and a validated cardiovascular risk tool. A score of zero indicates very low near-term risk; high scores indicate substantially elevated risk independent of other factors.

Matrix Gla protein (MGP): The most potent known inhibitor of arterial calcification. Synthesized in vascular smooth muscle cells; requires K2-mediated carboxylation to function. When K2 is insufficient, MGP remains inactive and cannot prevent calcium deposition.

Menaquinones (MK-4, MK-7): The two most studied forms of vitamin K2. MK-7 has a longer half-life and better tissue accumulation at supplement doses. MK-4 is studied at a pharmacological dose (45 mg daily) for osteoporosis in Japan — a different intervention from the typical Western MK-7 supplement.

Osteocalcin: A vitamin K-dependent protein that incorporates calcium into bone. Requires K2-mediated carboxylation to function; undercarboxylated (inactive) osteocalcin is a measurable indicator of K2 insufficiency.

Phylloquinone (vitamin K1): The form of vitamin K in green leafy vegetables. Distributed primarily to the liver for clotting-factor activation, without the tissue distribution or cardiovascular relevance of K2.

Uncarboxylated MGP: The inactive form of MGP, measurable in blood as an indicator of K2 status in peripheral tissues. Associated with greater arterial calcification in observational studies and reduced by K2 supplementation — confirming pathway activation, though this has not translated into reduced calcification in randomized trials.

References

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4. Luo G, Ducy P, McKee MD, et al. Spontaneous calcification of arteries and cartilage in mice lacking matrix GLA protein. Nature. 1997;386(6620):78–81.
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8. Diederichsen ACP, Lindholt JS, Möller S, et al. Vitamin K2 and D in patients with aortic valve calcification: a randomized double-blinded clinical trial. Circulation. 2022;145(18):1387–1397.
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