Vitamin K2
Vitamin K2 (Menaquinone)
Fat-soluble vitamin that directs calcium to bones instead of arteries, supporting cardiovascular and bone health.
Vitamin K2 activates proteins that regulate calcium metabolism, directing calcium into bones and teeth while keeping it out of arteries and soft tissues. MK-7 is the most bioavailable form. Essential when supplementing vitamin D and calcium. Most people don't get enough from diet alone.
Mechanisms of Action
Osteocalcin Activation
Activates the protein that binds calcium to bones
Arterial Protection
Keeps calcium out of blood vessels
Recommended Dose
100-200mcg (MK-7)
Optimal Timing
- With a meal containing fat
Take with food
Best Form
MK-7 (menaquinone-7)
Alternatives: MK-4 (requires higher doses, multiple times daily)
MK-7 has longer half-life (72 hours vs 6 hours for MK-4) and is effective at lower doses.
Duration
Minimum: 12 weeks
Optimal: weeks
Cycling: Not required
Note: Fat-soluble, so take with food containing fat for absorption. Often paired with vitamin D3.
Personalized Dosage Calculator
Get a dosage recommendation tailored to your body weight, age, goals, and health profile.
Set up your health profile for personalized recommendations
Improved Bone Health
Supports bone density when combined with D3 and calcium
Cardiovascular Support
May reduce arterial calcification over time
Likely safe at recommended doses; supports fetal bone development
Contraindicated with warfarin, heparin, and other anticoagulants without medical supervision. Vitamin K2 directly antagonizes the mechanism of these medications, potentially causing dangerous clot formation. Requires INR monitoring and physician approval.
Who Should NOT Take This
- Those taking warfarin or other vitamin K antagonists (consult doctor)
- Anticoagulant or blood thinner therapy (warfarin, heparin, Coumadin) — Vitamin K2 directly antagonizes warfarin's mechanism of action
Drug Interactions
Vitamin K2 promotes clotting factors that warfarin is designed to inhibit. Taking K2 can significantly reduce anticoagulant effectiveness, increasing risk of dangerous blood clots. Requires medical supervision and INR monitoring if used together.
Consult doctor before combining
Possible Side Effects
Tip: N/A
Warnings
- Critical interaction with warfarin and vitamin K antagonists
- Benefits are long-term — don't expect quick results
Top studies from 40+ peer-reviewed papers
Atieh O et al. • Nutrients (2025)
“Vitamins K2/D3 improved the RECOVER Long COVID Index, the number of LC symptoms, and several gut and inflammatory markers.”
Key Findings:
- The median age was 46 years; 71% were female and 29% were non-white.
- In the vitamin K2/D3 arm, there was a 7.1% decrease in the proportion who had an LC Index ≥12 (vs. a 7.2% increase in the SOC group; p = 0.01).
- The average number of LC symptoms remained stable in the vitamin K2/D3 arm but increased in the SOC arm (p = 0.03).
Zhang Z et al. • Frontiers in endocrinology (2025)
“Vitamin K2 supplementation improves key bone turnover biomarkers, particularly OC and ucOC.”
Key Findings:
- Vitamin K2 (VK2) increased osteocalcin (OC; MD 1.86, 95% CI 1.17-2.56) and bone-specific alkaline phosphatase (BAP; MD 1.49, 95% CI 0.98-2.00).
- It reduced undercarboxylated OC (ucOC; WMD -1.54, 95% CI -2.44 to -0.64) and tartrate-resistant acid phosphatase (TRAP; MD -0.83, 95% CI -1.21 to -0.46).
- C-terminal telopeptide (CTX) showed a small, statistically significant reduction (MD -0.09, 95% CI -0.14 to -0.05) with uncertain clinical relevance.
Tan J et al. • JAMA internal medicine (2024)
“This randomized clinical trial showed that vitamin K2 supplementation significantly reduced the frequency, intensity, and duration of NLCs in an older population with good safety.”
Key Findings:
- Of the 199 enrolled individuals, 108 (54.3%) were female, and the mean (SD) age was 72.3 (5.5) years.
- A total of 103 patients (51.8%) were randomly assigned to receive vitamin K2 and 96 (48.2%) were assigned to placebo.
- The between-group difference was statistically significant (difference, -2.67; 95% CI, -2.86 to -2.49; P < .001).
Zhao QY et al. • Journal of nutritional science (2024)
“We demonstrated that supplementation with vitamin K has no effect on anthropometrics indexes, CRP, glucose metabolism, and lipid profile factors except HOMA-IR.© The Author(s) 2024.”
Key Findings:
- Pooled weighted mean difference (WMD) and 95 % confidence intervals (95 % CI) were achieved by random-model effect analysis for the best estimation of outcomes.
- The pooled findings showed that vitamin K supplementation can reduce homeostatic model assessment insulin resistance (HOMA-IR) (WMD: -0⋅24, 95 % CI: -0⋅49, -0⋅02, P = 0⋅047) significantly compared to the placebo group.
- Subgroup analysis showed a significant effect of vitamin K2 supplementation compared to vitamin K1 supplementation on HOMA-IR.
- However, no significant effect was observed on other variables.
Ma ML et al. • Frontiers in public health (2022)
“The results of this meta-analysis seem to indicate that VK2 supplementation has a positive effect on the maintenance and improvement of BMD LS in postmenopausal women, and it can also reduce the fracture incidence, serum uc-OC levels and the ratio of uc-OC to cOC.”
Key Findings:
- The overall effect test of 10 studies showed a significant improvement in lumbar spine BMD (BMD LS) (P = 0.006) with VK2.
- The subgroup analysis of VK2 combination therapy showed that BMD LS was significantly maintained and improved with the administration of VK2 (P = 0.03).
- The overall effect test of the six RCTs showed no significant difference in fracture incidence between the two groups (RR=0.96, P=0.65).
- However, after excluding one heterogeneous study, the overall effect test showed a significant reduction in fracture incidence with VK2 (RR = 0.43, P = 0.01).
Study Type Distribution
Goals This Supplement Supports
Related Goals
This information is for educational purposes only and is not intended as medical advice. Always consult a qualified healthcare provider before starting any supplement.