A long-chain menaquinone produced by bacterial fermentation, originally identified in natto — fermented soybeans — and now made commercially with Bacillus subtilis. Its long side chain gives it a blood half-life of around three days, far longer than K1 or MK-4.
MK-7 is the vitamin K form with the best pharmacokinetics and the thinnest outcome data. A microgram dose raises blood levels for days and lowers undercarboxylated osteocalcin more efficiently than K1, which is why it dominates the supplement market. What it does not have is a fracture trial: the main three-year study in postmenopausal women reported modest preservation of bone strength measures at 180 µg/day, and a separate trial reported slower arterial stiffening, but neither measured fractures or cardiovascular events, and independent replication is limited. The marketing sits several steps ahead of the evidence.
Sold as
Softgel in oil, Capsule, Drops, Combination with vitamin D3, Natto extract
Standardised to
Usually stated as µg MK-7; all-trans content matters and is rarely disclosed — a product without this marker may not resemble what was studied.
Also known as
Menaquinone-7, MK-7, Natto-derived vitamin K2
Regulation: No Tolerable Upper Intake Level exists for vitamin K in any form. EFSA has assessed MK-7 as safe at the doses sold but has authorised only a general bone-maintenance claim for vitamin K, not a fracture claim. Sold in the US as a dietary supplement with no pre-market efficacy review.
What the research used
The amounts, forms and durations published trials of Vitamin K2 (MK-7) actually administered.
These are the amounts published trials administered — not a recommendation, and not a dose to copy. Trial participants were screened, supervised and given a characterised preparation. What is in a retail bottle is frequently not what was studied, and the amount that suits one person is not general advice.
Studied for Bone and arterial stiffness trials
180–360 µg
Limited
MK-7 softgel, daily · 3 years
The 180 µg dose is the most cited. Outcomes were bone strength indices, undercarboxylated osteocalcin and pulse wave velocity — not fractures or cardiovascular events. Several trials were supported by MK-7 manufacturers.
Studied for Typical retail supplement
45–200 µg
Not enough
Softgel, often with vitamin D3
The 45 µg products supply less than the studied dose. Product analyses have also found variable all-trans MK-7 content, with the cis isomer biologically inactive.
This is general information about food, not medical advice. It cannot diagnose, treat or replace guidance from a clinician who knows your history.
When it was taken
Each window says whether a trial compared it against an alternative, or whether it is convention and pharmacology. Most timing advice is the second kind.
1 of 2 timings below were actually compared in a trial. The rest reflect convention or pharmacology.
🍽️With food
Moderate
Fat-soluble and better absorbed with a fat-containing meal, which absorption studies have measured across vitamin K forms.
Timing was tested. A trial compared this window against another and reported a difference.
🕐Any time
Limited
The roughly three-day half-life means blood levels stay elevated between doses, so time of day is unlikely to matter. That follows from the pharmacokinetics rather than from a trial comparing schedules.
Timing was not directly compared. This reflects convention or how the compound behaves in the body, not a trial showing this window works better.
The evidence in depth
Best supported: Limited
What each association actually rests on, and the papers behind it. A rating describes the state of the research, not how promising the supplement sounds. How we rate evidence.
A three-year trial at 180 µg/day reported better-preserved bone strength measures in postmenopausal women than placebo, alongside consistent reductions in undercarboxylated osteocalcin. No trial has measured fracture rates, and the bone density differences were small.
What may be going on: Carboxylation of osteocalcin allows it to bind calcium in the bone matrix; MK-7 achieves this at lower doses than K1 because it remains in circulation far longer.
Limited evidence. Early human work, or mostly lab and animal research.
Randomised controlled trial · Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA · 2013 · PMID 23525894
One three-year trial reported less arterial stiffening with 180 µg/day, and observational data associate higher menaquinone intake with less coronary calcification. Trials in dialysis and aortic stenosis populations have been largely null, and no trial has measured cardiovascular events.
What may be going on: Matrix Gla protein requires vitamin K–dependent carboxylation to inhibit calcium deposition in vessel walls; uncarboxylated forms circulate at higher levels when vitamin K status is low.
Limited evidence. Early human work, or mostly lab and animal research.
Randomised controlled trial · Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association · 2023 · PMID 36460034
Deep research mode adds each paper’s own conclusion and stated limitations.
Things to know
Interactions, contraindications and dose limits, most serious first. Concentrated extracts interact with medication in ways the whole plant does not, so this section carries more weight here than it does on a food page.
Interaction
Antagonises warfarin, and the long half-life makes it harder to manage
MK-7 stays in circulation for days, so its effect on the INR persists well after a dose is missed or stopped. Anyone on warfarin or another vitamin K antagonist should not start or stop it without telling their anticoagulation service. Consistency of intake, not avoidance, is what keeps control stable.
Worth knowing
Isomer content is rarely disclosed
Only the all-trans form is biologically active, and independent testing has found products containing appreciable cis-MK-7. A label stating micrograms of MK-7 without specifying all-trans content does not tell you how much active material is present.
Worth knowing
Marketed well beyond its evidence
Claims that MK-7 moves calcium out of arteries and into bone are extrapolated from marker studies. No trial has demonstrated a fracture or cardiovascular event benefit, and that gap is not disclosed on any product this catalogue has reviewed.
Allergy
Soy-derived in most products
Fermentation-derived MK-7 usually starts from soybeans. Residual soy protein is minimal in purified extracts but people with severe soy allergy sometimes prefer chickpea-fermented alternatives.
In the food catalogue
The whole-food form, where one exists. The evidence for a concentrated extract rarely transfers to the food, or the other way round — these are cross-links, not equivalents.