Vitamin K2
Menaquinone
Directs calcium to bone, away from arteries.
Evidence tier
Preliminary
Research weight
Citations
15 verified / 15
Classification
Vitamin
❝
What the evidence says. Early or small human trials; promising but not yet conclusive.
What is Vitamin K2?
Vitamin K2 (Menaquinone) is a vitamin used for bone mineralization. NutriDex grades the human evidence as Preliminary. Vitamin K2 activates proteins (osteocalcin, matrix Gla protein) that route calcium into bone and away from arterial walls. Observational data link higher K2 intake to less arterial calcification, and some trials show improved bone markers and reduced arterial stiffness. It is frequently paired with vitamin D. Cardiovascular-outcome evidence is still early.
Purported Benefits
✓Bone mineralization
✓Possible arterial-calcium reduction
✓Works with vitamin D
Evidence by outcome
The same supplement can be well-proven for one use and unproven for another — here is the human evidence graded outcome by outcome.
| Outcome | Evidence | Effect | Studies |
|---|---|---|---|
| Bone mineral density / fracture16-RCT MA (n=6,425) found improved lumbar BMD and fewer fractures in postmenopausal women. | Moderate | ↑ benefit · small | 4 |
| Coronary/arterial calcification progressionA 14-RCT MA found slowed CAC, but AVADEC and Trevasc-HDK RCTs showed no benefit at studied doses. | Mixed | ↔ mixed · small | 4 |
| Osteocalcin carboxylation (bone markers)Consistently raises carboxylated and lowers undercarboxylated osteocalcin across RCTs — a reliable biomarker effect. | Strong | ↑ benefit · moderate | 3 |
| Conventional cardiovascular risk factors2024 SR/MA found no significant effect on most CV risk factors beyond calcification markers. | Moderate | — no effect · negligible | 1 |
| Arterial stiffnessMK-7 slowed stiffness progression in a 3-yr trial and in dialysis patients; outcome data still early. | Preliminary | ↑ benefit · small | 2 |
Dosing & Compounds
Typical Dose
90–180 µg/day MK-7.
Active Compounds
Safety & Cautions
Safe. Interferes with warfarin — avoid if on it without medical supervision. Educational only — always check with your doctor or pharmacist before combining Vitamin K2 with any medicine.
Vitamin K2 drug interactions
Known or theoretical interactions between Vitamin K2 and common medications — educational, not exhaustive. Always check with your doctor or pharmacist before combining Vitamin K2 with any medicine.
Caution
Warfarin
Vitamin K2 REDUCES warfarin's blood-thinning effect (lowers INR); fluctuating intake risks clots.
Warfarin blocks vitamin K recycling; supplemental K directly counteracts it, restoring clotting factors. NIH ODS — Vitamin K
Key Studies ★ 15 studies
meta-analysis
Bellinge 2023 (meta-analysis)
✓ PubMed
Systematic review/meta-analysis of 14 RCTs (n=1,533) found vitamin K supplementation significantly slowed progression of coronary artery calcification scores versus placebo.
systematic review
Vitamin K & CV risk factors 2024 (meta-analysis)
✓ PubMed
Systematic review and meta-analysis of RCTs found vitamin K supplementation had no significant overall effect on most conventional cardiovascular risk factors, with effects largely limited to calcification markers.
Meta-analysis
Frontiers Endocrinol 2025
✓ Full text
Meta-analysis of 9 RCTs (2,570 postmenopausal osteoporosis patients) found vitamin K2 increased osteocalcin and bone-specific alkaline phosphatase, reduced undercarboxylated osteocalcin and TRAP, with a small statistically significant CTX reduction of uncertain clinical relevance.
Meta-analysis
Bone Joint Res 2024
✓ Full text
Meta-analysis/systematic review of RCTs in middle-aged and elderly adults found vitamin K (especially K2) increased lumbar spine BMD (p=0.035), raised carboxylated osteocalcin (p=0.004) and decreased uncarboxylated osteocalcin (p<0.001).
meta-analysis
Ma 2022 (meta-analysis)
✓ PubMed
Systematic review/meta-analysis of 16 RCTs (n=6,425) found vitamin K2 significantly improved lumbar spine BMD and reduced fracture incidence in postmenopausal women with or at risk of osteoporosis.
randomized controlled trial
MK-7 arterial stiffness 2023 (RCT)
✓ PubMed
Multicenter RCT in chronic hemodialysis patients found menaquinone-7 supplementation slowed progression of arterial stiffness versus placebo.
RCT
MK-7 glycemic homeostasis & gut microbiome 2023 (RCT)
✓ PubMed
Six-month double-blind RCT in 60 type 2 diabetes patients found MK-7 supplementation improved glycemic control (reductions of ~13% fasting glucose, ~28% insulin, ~7% HbA1c) and insulin sensitivity, with mechanistic links to altered gut microbiome, secondary bile acids and short-chain fatty acids.
RCT
Trevasc-HDK 2023 (RCT)
✓ PubMed
Randomized controlled trial in 178 maintenance hemodialysis patients found menaquinone-7 360 ug three times weekly over 18 months did NOT significantly slow progression of coronary artery calcification versus control (no beneficial effect on vascular calcification at the studied dose/duration).
randomized controlled trial
RenaKvit 2022 (RCT)
✓ PubMed
Double-blind RCT in 123 chronic dialysis patients found 360 ug/day MK-7 over 2 years prevented lumbar spine BMD loss but accelerated BMD loss at the distal radius versus placebo.
randomized controlled trial
AVADEC 2022 (RCT)
✓ PubMed
Randomized double-blind multicenter trial in men with aortic valve calcification >300 AU found 720 ug MK-7 plus vitamin D over 24 months did not significantly slow aortic valve calcification progression versus placebo.
randomized controlled trial
MK-7 adiponectin 2021 (RCT)
✓ PubMed
RCT in postmenopausal women found 12 months of MK-7 increased plasma adiponectin and reduced undercarboxylated osteocalcin but did not improve insulin sensitivity.
cohort
NAFLD vitamin K & mortality 2025 (cohort)
✓ PubMed
Prospective NHANES analysis of 7,857 non-alcoholic fatty liver disease patients (842 deaths over up to 180 months) found higher dietary vitamin K intake associated with lower all-cause mortality (adjusted HR 0.81 per unit increase, 95% CI 0.67-0.98, P-trend=0.028).
Observational
Rotterdam Study
✓ PubMed
Higher dietary K2 associated with less coronary calcification.
Study
Knapen 2015
✓ PubMed
Reduced arterial stiffness over 3 years.
Study
Knapen 2013
✓ PubMed
MK-7 improved bone-related markers in postmenopausal women.