Full profile
| Also known as | Menaquinone-7, MK-7, Menaquinone |
|---|---|
| Best for | Directing calcium toward bone alongside vitamin D (limited evidence) · Foundational cofactor for a vitamin D3 regimen · Not studied for cognition |
| Evidence grade | Grade C — Limited — early or small human trials |
| Studied dose range | 90–180 mcg/day of MK-7, typically taken alongside vitamin D3 and with a fat-containing meal for absorption. |
| Time to effect | Not acute; vitamin K-dependent proteins (osteocalcin, matrix Gla protein) are carboxylated over weeks of consistent daily use. |
| Best form | MK-7 (menaquinone-7) over MK-4 or K1 — MK-7 has a longer half-life and better-studied dosing in the trials above. |
| Food sources | Natto (fermented soybeans, by far the richest source), Hard and soft cheeses, Egg yolks, Chicken liver |
Evidence, honestly graded
Claim-specific grading: for bone/working-with-D, a 2022 meta-analysis of 16 RCTs (Ma 2022, Frontiers in Public Health, PMID 36033779) found MK-7 supplementation has a positive effect on lumbar-spine bone mineral density in postmenopausal women, particularly combined with vitamin D or calcium — evidence is real but the trial base is still limited and mixed, so this is graded C, not B. For the arterial-calcification/cardiovascular angle, the evidence is Emerging: a 2023 meta-analysis of 14 RCTs (Li 2023, Frontiers in Nutrition, PMID 37252246) found vitamin K supplementation slowed coronary-artery-calcification progression, and a 2023 RCT in older men (Hasific 2023, JACC Advances, PMID 38938724 — the AVADEC trial, MK-7 720 mcg/day + vitamin D3) found no significant difference in the full study population but did find significantly slower CAC progression in a higher-risk subgroup with baseline CAC ≥400. That is a real, hypothesis-generating signal from one higher-risk-population RCT, not a confirmed effect — replication in broader populations is needed before this claim could move past Emerging.
See the full grading rubric — study type, replication, population match, and dose adequacy — in The Evidence Standard.
Side effects
- Very well tolerated at supplemental doses
- No established toxicity at typical supplemental intakes
Who should avoid it or check first
- Taking warfarin or another vitamin K antagonist without physician supervision — vitamin K directly opposes how these drugs work
- Pregnant or breastfeeding without clinician guidance
Interactions
- Directly antagonizes warfarin and other vitamin K antagonist anticoagulants — even low supplemental doses can meaningfully reduce their effect; anyone on these medications must not add vitamin K2 without physician and INR monitoring
- May interact with other anticoagulant or antiplatelet therapy — discuss with a clinician
Stacks well with
- Vitamin D3
- Magnesium
Use caution stacking with
- Warfarin or other vitamin K antagonist medication without physician supervision
What to look for on a label
- State the form (MK-7 vs MK-4) and the microgram amount — 'vitamin K' alone does not specify which form or dose.
- A product pairing D3 with K2 should carry a visible anticoagulant-interaction warning given how common warfarin and DOAC use is in the exact demographic (older adults) most likely to buy a bone-health product.
References
- Ma 2022, Frontiers in Public Health — meta-analysis (16 RCTs). Vitamin K2 (MK-7) supplementation improved lumbar-spine bone mineral density in postmenopausal women, especially combined with vitamin D or calcium. PMID 36033779; doi:10.3389/fpubh.2022.979649. Primary basis for the C grade on bone/works-with-D. Educational, not a product claim.
- Li 2023, Frontiers in Nutrition — meta-analysis (14 RCTs). Vitamin K supplementation had a significant effect on coronary-artery-calcification scores, slowing CAC progression. PMID 37252246; doi:10.3389/fnut.2023.1115069. Educational.
- Hasific 2023, JACC Advances — AVADEC RCT. MK-7 (720 mcg/day) + vitamin D3 in ~300 older men found no significant difference in CAC progression overall, but significantly slower progression in the higher-risk subgroup with baseline CAC ≥400. PMID 38938724; doi:10.1016/j.jacadv.2023.100643. Basis for the Emerging grade on the cardiovascular claim — hypothesis-generating, not confirmed.
Grades and studied doses are our conservative reading of the human research, shown for education. They are not product claims, and a studied dose is not a recommended dose.
See how Vitamin K2 (MK-7) compares on grade, dose, and goal in the Evidence Explorer.