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Comparative guide · 5 min read

Vitamin K2: MK-4 vs MK-7 — what's actually different

Updated 2026-05-11 · Reviewed by SupplementScore editors · No sponsorships

Vitamin K comes in two main dietary forms: K1 (phylloquinone, from leafy greens, the primary substrate for hepatic clotting factor synthesis) and K2 (menaquinones, with side chains of varying length, the form associated with bone and vascular endpoints). K2 itself has multiple subtypes; the two that matter for supplements are menaquinone-4 (MK-4) and menaquinone-7 (MK-7). They share a vitamin K nucleus but differ in side-chain length, half-life, and the trials that have actually been done with them.

Quick verdict

GoalBetter choiceWhy
Bone density, postmenopausal women, Japan-derived high-dose protocol MK-4 (pharmaceutical dose) Japanese trials and the prescription drug Glakay use MK-4 at 45 mg/day (three divided doses); this dose has the largest body of fracture-prevention evidence, predominantly in Japanese populations.
Once-daily convenience, K2 status maintenance, general supplementation MK-7 ~3-day half-life means once-daily dosing produces stable plasma levels at much smaller doses (90–200 mcg/day). Most modern K2 supplements use this.
Vascular calcification (arterial stiffness) MK-7 (modest signal) Knapen 2015 (3-year MK-7 180 mcg/day) showed reduction in arterial stiffness in postmenopausal women; small effect, replication limited.
Osteoporosis treatment as primary therapy Neither — bisphosphonates or zoledronic acid lead K2 is at best a small-effect adjunct; primary osteoporosis treatment is anti-resorptive pharmacology.
Cost per day at typical maintenance dose MK-7 $0.10–0.25/day for 100–200 mcg; MK-4 at supplement-marketed micro-doses is roughly equivalent, but the pharmaceutical-dose MK-4 (45 mg/day) is significantly more expensive.

How they compare on the things that matter

Pharmacokinetics — the central difference

MK-4 has a plasma half-life of approximately 1–2 hours. To maintain steady-state plasma levels, MK-4 must be dosed multiple times per day, which is why pharmaceutical trial protocols use 15 mg three times daily (45 mg/day total). At typical supplement doses (1–5 mg/day, once daily), MK-4 plasma levels are detectable only briefly and may not reproduce the effects observed in pharmaceutical-dose trials.

MK-7 has a plasma half-life of approximately 68–84 hours (around 3 days). This is the central pharmacokinetic advantage: once-daily dosing at 90–200 mcg produces stable plasma menaquinone-7 levels and sustained carboxylation of vitamin K-dependent proteins (osteocalcin, Matrix Gla Protein). The pharmacokinetic profile is the main reason MK-7 dominates the modern K2 supplement market.

Evidence base — different studies, not interchangeable

MK-4's evidence base is largely from Japan, where pharmaceutical menatetrenone (Glakay) at 45 mg/day is approved for osteoporosis. Trials in Japanese postmenopausal women support fracture reduction. The applicability of these trials to non-Japanese populations and to the much lower MK-4 doses commonly found in supplements is uncertain. The Cochrane review on vitamin K supplementation for fracture prevention found benefit primarily in the Japanese MK-4 trials and noted heterogeneity that limits generalisability.

MK-7's evidence base comes mostly from European trials (especially Dutch groups). Knapen 2013 (postmenopausal women, MK-7 180 mcg/day for 3 years) showed slowing of bone mineral density loss at lumbar spine and femoral neck. Knapen 2015 (same group) showed reduction in arterial stiffness over 3 years. The effect sizes are smaller than the Japanese MK-4 trials but the dose is realistic for everyday supplementation.

What about K2 in deficiency vs adequacy?

Standard Western diets typically provide enough K1 to cover hepatic clotting factor needs but variable K2. Whether modern Western populations have functional K2 inadequacy at the level of bone and vascular protein carboxylation is debated. Undercarboxylated osteocalcin (ucOC) is a marker of suboptimal K2 status; populations with higher K2 intake (notably Japanese natto consumers) have lower ucOC and lower fracture rates, but the causal chain is contested. The honest summary: K2 supplementation is unlikely to harm and may help bone and vascular protein carboxylation, with modest effect sizes that are larger in populations with low baseline K2 intake.

Practical rule. For most users wanting a once-daily K2 alongside their D3 — MK-7 90–180 mcg/day is the simpler, better-supported-in-Western-populations choice. For users specifically attempting to replicate the Japanese fracture-prevention literature (postmenopausal women, severe osteoporosis, ideally under specialist care) — pharmaceutical-dose MK-4 (45 mg/day in three divided doses) is the dose that was actually studied; supplement-marketed micro-dose MK-4 (1–5 mg/day) is neither the trial dose nor the convenient form.

Dose and form

For MK-7, trial-cited doses range from 90 mcg/day to 360 mcg/day, with 180 mcg/day being the most commonly studied. All-trans MK-7 (from natto or fermentation) is the active stereoisomer; cis-isomers are biologically inactive. Reputable brands specify "all-trans" or "MenaQ7" (Gnosis branded form used in many trials). Take with a fatty meal.

For MK-4, supplement market doses (1–5 mg/day) do not replicate the Japanese pharmaceutical trial dose (45 mg/day). If chasing the trial dose, prescription menatetrenone (Glakay; Japan) is the form, used in three divided doses with food. Supplement-grade MK-4 at 5 mg/day is reasonable as a maintenance K2 strategy in users who prefer it, but should not be expected to reproduce the high-dose fracture-prevention effects.

Safety and drug interactions

Both forms are well-tolerated. The most important interaction is with warfarin and other vitamin K antagonists — K2 supplementation can interfere with anticoagulant control. Users on warfarin should maintain a consistent K intake rather than vary it; supplementing without coordination with the prescriber risks INR destabilisation. K2 does not affect direct oral anticoagulants (DOACs) the same way.

K2 supplementation does not appear to increase thrombotic events in non-anticoagulated populations. Long-term safety at supplemental doses is adequate. Pregnancy-specific data is limited; supplementation during pregnancy beyond what's needed for clotting factor synthesis is not established.

The D3+K2 combination question

D3 and K2 are often co-marketed on the premise that K2 directs calcium "where it belongs" (bone) and "away from where it doesn't" (arteries). The mechanism (K2-dependent carboxylation of Matrix Gla Protein, an inhibitor of vascular calcification) is real. The clinical evidence that adding K2 to D3 supplementation produces meaningful additional bone or cardiovascular protection is modest. Reasonable to combine if you're already supplementing D3; not essential for everyone.

Who should skip each

K2 (either form) should be avoided in users on warfarin or other vitamin K antagonists without prescriber coordination. Users on DOACs (apixaban, rivaroxaban, dabigatran) do not have the same interaction. Discuss with prescriber if on chronic anticoagulants of any kind.

Pregnancy supplementation beyond what's in standard prenatals is not established; check with obstetric care. Active malignancy with bone involvement requires oncology coordination before adding bone-modifying agents.

What we'd actually buy

For most adults adding K2 to a D3 supplement for general bone and vascular health: all-trans MK-7 90–180 mcg/day in a brand specifying "MenaQ7" or third-party verification of the all-trans content. Once-daily with a fatty meal.

For postmenopausal women with established osteoporosis seeking a K2 strategy: discuss pharmaceutical-dose MK-4 (45 mg/day) with the prescriber managing osteoporosis. Outside Japan this is rarely first-line; bisphosphonates, denosumab, or anabolic agents typically lead the regimen.

For users seeking a single combined D3 + K2 product: any reputable D3 + MK-7 combination at D3 1,000–2,000 IU + MK-7 100–180 mcg is reasonable. Avoid combination products that don't specify the MK-7 dose in micrograms.

Sources

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