Compound or practice · Supplement
Vitamin K2
The traffic cop for calcium — activates proteins that steer it into bone and away from arteries.
- Overall grade
- Grade B
- Last revised
- 3
- graded outcomes
- 1
- reference listed
A structured monograph in Prometheus's bundled library. Its grades are the monograph's own reading of the evidence, not a peer-reviewed review.
1 at grade A · 1 at grade B · 1 at grade C — 3 graded rows
What is known
Each outcome with its grade (how strong the evidence is, A to D), the size of the effect where the entry records one, and how often studies agree.
- Osteocalcin carboxylationEvidence grade A
Reliable surrogate improvement
Largehigh
- Arterial stiffness markersEvidence grade B
Some trials positive over 3 years
Smallmixed
- Fracture reductionEvidence grade C
Hard-outcome data limited
Unclearlow
What is uncertain
Read off the same rows as above. Nothing here is added that the entry does not itself record.
- Thin evidence: Fracture reduction (grade C).
- Studies disagree: Arterial stiffness markers (mixed agreement).
- Caution with Anticoagulants (warfarin): Antagonizes vitamin-K-antagonist anticoagulants; keep intake constant and clear it medically.
Interactions
Documented pairings with supplements and medicines. A medicine on this list is a conversation for whoever prescribes it.
Anticoagulants (warfarin)Caution
Antagonizes vitamin-K-antagonist anticoagulants; keep intake constant and clear it medically.
Vitamin DWorks together
The canonical pairing — D mobilizes calcium, K2 directs it.
The evidence in words
What it is
Vitamin K exists as K1 (phylloquinone, from greens, drives clotting) and K2 (menaquinones, from ferments and animal foods, drives tissue calcium handling). MK-7 is the long-acting K2 form used in supplements. It is distinct from K1 in half-life and tissue distribution.
How it works
K2 is the cofactor that carboxylates (activates) two calcium-binding proteins: osteocalcin, which incorporates calcium into bone matrix, and matrix Gla protein, which inhibits calcium deposition in arterial walls. Without adequate K2, both proteins stay under-carboxylated and calcium handling drifts the wrong way.
What the evidence shows
The mechanistic story is strong and the surrogate markers (under-carboxylated osteocalcin, arterial stiffness measures) move in the right direction with supplementation. Hard-outcome evidence — fewer fractures, fewer cardiovascular events — is thinner and mostly from observational data plus a few trials. It earns a B for being a sensible, low-risk pairing with vitamin D rather than a proven independent life-extender.
How to use it
90–180 µg MK-7 daily, taken with vitamin D and a fatty meal. There is no benefit to megadosing.
Safety & interactions
Very safe. The critical exception: K2 (like K1) antagonizes warfarin and other vitamin-K-antagonist anticoagulants — anyone on warfarin must keep vitamin K intake consistent and cleared with their prescriber. It does not interact with the newer DOAC anticoagulants. Vitamin D — The canonical pairing — D mobilizes calcium, K2 directs it. warfarin — Antagonizes vitamin-K-antagonist anticoagulants; keep intake constant and clear it medically.
Bottom line
A cheap, low-risk companion to vitamin D that makes mechanistic sense for bone and vascular calcium handling. 90–180 µg MK-7 with your D. If you take warfarin, do not add it without medical guidance.
How it is used
As the entry records it, from the studies it summarises. Not a recommendation for you — doses that suit a trial population may not suit you.
- Standard
- 90–180 µg MK-7 daily with vitamin D and fat.
Goes with
- Vitamin DThe canonical pairing — D mobilizes calcium, K2 directs it.Evidence grade A
Related reading
Entries that share this one's tags or conditions.
- Vitamin K2 for Arterial stiffness markersEvidence grade B — Some trials positive over 3 yearsEvidence grade B
- Vitamin K2 for Fracture reductionEvidence grade C — Hard-outcome data limitedEvidence grade C
- Vitamin K2 for Osteocalcin carboxylationEvidence grade A — Reliable surrogate improvementEvidence grade A
- Vitamin K2: dosage and how to take it90–180 µg MK-7 daily with vitamin D and fat.Evidence grade B
Sources
As this entry records them: title, journal and year. None carries a DOI or PubMed id, so none is linked as a verified paper. Each link searches PubMed for the title; check that what you find is what the entry describes.
- 1.Menaquinone-7 supplementation and arterial stiffness — Thromb Haemost, 2015. Search PubMed (opens in a new tab)
Last revised . A grade is this entry's reading of the evidence, not medical advice.