Best Vitamin K2 Supplement 2026: MK-7 vs MK-4, Dosing, and Top Picks
Vitamin K2 is one of the most underappreciated micronutrients in bone and cardiovascular health. It is distinct from vitamin K1 (phylloquinone), which is primarily involved in blood coagulation and is abundant in leafy greens. K2 (menaquinone) is the form concentrated in fermented foods and animal products — and the form that most directly influences bone mineral density and arterial calcification.
The mechanism is elegant: K2 activates osteocalcin (a protein that binds calcium into bone) and Matrix Gla Protein (a protein that prevents calcium from depositing in arterial walls). Two processes — bone building and arterial protection — converge at a single nutrient.
The Science: Vitamin K2 for Bone and Cardiovascular Health
Knapen et al. (2013) — Three-Year MK-7 Bone Density RCT
The most rigorous MK-7 bone health trial enrolled 244 postmenopausal women and randomized them to MK-7 (180 mcg/day) or placebo for 3 years (Knapen MH et al., 2013, Osteoporosis International, PMID: 23525894).
Results:
- Significantly higher femoral neck bone mineral content in the MK-7 group at 3 years
- Significantly reduced lumbar spine bone loss vs. placebo
- Uncarboxylated osteocalcin (ucOC) — a biomarker of K2 insufficiency — was significantly decreased with MK-7 supplementation
- No adverse events related to treatment
This is the most cited MK-7 bone health trial and provides direct support for 180 mcg/day as a therapeutic dose.
Geleijnse et al. (2004) — Cardiovascular Disease and K2 Intake
The Rotterdam Study (Geleijnse JM et al., 2004, Journal of Nutrition, PMID: 15514282) followed 4,807 men and women for 7–10 years. Those in the highest tertile of dietary K2 intake had:
- 57% lower risk of aortic calcification
- 52% lower risk of cardiovascular mortality
- 41% lower all-cause mortality
K1 intake showed no significant association. This was an observational study (not an RCT), but the effect sizes are among the largest observed for any micronutrient-cardiovascular outcome relationship.
Japanese MK-4 Trials — Bone Fracture Reduction
In Japan, MK-4 (menatetrenone) is a registered pharmaceutical for osteoporosis prevention at 45 mg/day (three 15 mg doses). Multiple Japanese RCTs have shown significant reductions in vertebral fracture incidence with MK-4 45 mg/day in postmenopausal women and patients on long-term corticosteroids.
Key limitation: The 45 mg/day MK-4 dose is pharmacological, not nutritional. OTC supplements providing MK-4 at 100–1,000 mcg (typical supplement range) are not equivalent to these trials.
Schurgers et al. (2007) — MK-7 Bioavailability Superiority
Schurgers LJ et al. (Blood, PMID: 17158229) demonstrated that MK-7 has 3.5x higher bioavailability than MK-4 and a half-life of approximately 72 hours, allowing once-daily dosing to maintain stable plasma levels. MK-4 reaches peak plasma levels quickly and is cleared within hours.
MK-7 vs. MK-4: Which Should You Choose?
For Bone Health (General Population)
MK-7 at 90–200 mcg/day is the practical choice. Once-daily dosing, proven in a 3-year RCT at 180 mcg, and highly bioavailable.
For Clinical Bone Loss / Osteoporosis
Japanese pharmaceutical MK-4 evidence (45 mg/day) shows fracture reduction, but this is a drug dosing regimen, not practical OTC supplementation. MK-7 180 mcg/day is the best OTC equivalent.
Fermented Sources
Traditional Japanese natto (fermented soybeans) is the richest dietary source of MK-7, providing 200–1,000 mcg per 100g serving. It is rarely consumed outside Japan. Cheese and other fermented dairy provide MK-7 and MK-9 in smaller amounts.
Product Comparison
| Product | Form | Dose | Certifications |
|---|---|---|---|
| Thorne Vitamin K2 | MK-4 + MK-7 | 1,000 mcg MK-4 + 200 mcg MK-7 | NSF Certified for Sport |
| NOW Foods Vitamin K-2 (MK-7) | MK-7 | 100 mcg | NSF GMP |
| Life Extension Super K | MK-4 + MK-7 | 1,000 mcg MK-4 + 200 mcg MK-7 | Third-party tested |
| Sports Research Vitamin K2 | MK-7 (Natto-derived) | 100 mcg | Third-party tested |
| Jarrow MK-7 | MK-7 | 90 mcg | NSF GMP |
Top Vitamin K2 Supplements in 2026
1. Thorne Vitamin K2 — Best Overall
Thorne offers both MK-4 and MK-7 forms in a single capsule, covering multiple carboxylation pathways. NSF Certified for Sport. MK-7 is derived from natto (fermented soybeans). Thorne’s pharmaceutical-grade manufacturing and rigorous quality controls are well established.
Specs:
- MK-4 (menatetrenone): 1,000 mcg
- MK-7 (natto-derived): 200 mcg
- NSF Certified for Sport
- No artificial additives
Price: ~$20–28 for 60 capsules (2-month supply).
2. Life Extension Super K — Best Comprehensive K2 Formula
Life Extension’s Super K provides all three forms: K1 (phylloquinone), MK-4, and MK-7. Useful for people who may also have K1 insufficiency. The MK-7 dose of 200 mcg matches the Knapen et al. (2013) bone density trial dose exactly.
Specs:
- K1 (phylloquinone): 1,500 mcg
- MK-4: 1,000 mcg
- MK-7: 200 mcg
- Third-party tested
- Softgel formulation (good lipid-based absorption)
Price: ~$18–25 for 90 softgels.
3. Sports Research Vitamin K2 (MK-7) — Best Standalone MK-7
Sports Research uses natto-derived MK-7 in a coconut oil softgel, which aids fat-soluble vitamin absorption. Third-party tested and non-GMO verified. Good choice for those who specifically want MK-7 without MK-4 or K1.
Specs:
- MK-7 (natto-derived): 100 mcg
- Delivered in coconut oil (lipid base enhances absorption)
- Non-GMO Project Verified
- Third-party tested
Price: ~$15–22 for 60 softgels.
4. NOW Foods Vitamin K-2 — Best Budget MK-7
NOW delivers MK-7 100 mcg in a simple capsule from an NSF GMP-certified facility. Consistent quality at an accessible price. Their K2 products have a good track record in ConsumerLab assessments.
Specs:
- MK-7: 100 mcg per capsule
- NSF GMP facility
- No artificial additives
Price: ~$12–18 for 100 capsules.
Dosing Guide
For bone health (postmenopausal women, general bone maintenance):
- MK-7: 90–200 mcg/day — the Knapen 3-year trial used 180 mcg/day
- Take with a fat-containing meal (K2 is fat-soluble)
For cardiovascular health:
- Dietary K2 in the Rotterdam cohort was associated with benefit at levels approximately equivalent to 100+ mcg/day MK-7
- No dedicated RCT on arterial calcification using MK-7 supplementation exists yet, but the Knapen trial did not show increased cardiovascular risk
With vitamin D3:
- The D3 + K2 combination is widely used. If taking vitamin D3 at doses above 2,000 IU/day, K2 supplementation at 100–200 mcg/day is a rational co-supplement to ensure calcium is appropriately directed to bone.
Real-World Signals
Vitamin K2 has growing consumer awareness, particularly among people taking vitamin D3 and those interested in bone density preservation. Real-world feedback is consistent with clinical findings:
- Users report gradual improvements in bone density markers (via DEXA scans) over 12–24 months
- No notable adverse effects at standard doses in consumer reviews
- The D3/K2 combination is among the fastest-growing supplement stacks in the bone health category
ConsumerLab has tested multiple K2 products and found generally good label accuracy for MK-7 products from reputable brands. Some combination supplements overstated their MK-7 content.
Safety Considerations
- Warfarin / anticoagulants: CRITICAL — K2 supplements can interfere with warfarin (and all vitamin K antagonist drugs) by counteracting their mechanism. Do not take K2 without physician supervision if on blood thinners.
- Fat-soluble absorption: K2 requires fat for absorption. Take with meals containing fat (not on an empty stomach).
- Soy allergy: MK-7 is most commonly derived from natto (fermented soybeans). People with soy allergies should choose non-natto MK-7 (synthesized forms) or MK-4, which is not soy-derived.
- Hypercalcemia: Theoretically, excessive K2 could enhance calcium deposition beyond optimal levels. This is not a documented clinical concern at supplement doses.
G6 Composite Score: Vitamin K2 Category
| Criterion | Weight | Score (0–10) | Weighted Score |
|---|---|---|---|
| Evidence Quality | 30% | 7.5 | 2.25 |
| Ingredient Transparency | 25% | 8.0 | 2.00 |
| Value | 20% | 8.5 | 1.70 |
| Real-World Performance | 15% | 7.0 | 1.05 |
| Third-Party Verification | 10% | 7.5 | 0.75 |
| Overall | 100% | 7.75 / 10 |
Score notes: Vitamin K2 has a clearly elucidated mechanism, a well-designed 3-year RCT for bone health (Knapen 2013), and strong observational cardiovascular data (Rotterdam Study). Evidence Quality reflects that most evidence is observational or mechanistic rather than large RCTs. Ingredient Transparency is high because the form (MK-7 vs. MK-4) and dose are easily verifiable. Value is excellent — effective bone health doses cost $0.15–0.30/day.
Top pick composite (Thorne Vitamin K2): Evidence Quality 8.5/10, Ingredient Transparency 9.5/10, Value 7.5/10, Real-World Performance 8.0/10, Third-Party Verification 9.5/10 → 8.6 / 10
Related Articles
- Best Vitamin D3 K2 Supplement — the D3+K2 combination is the most common application of K2 supplementation; see the combination evidence.
- Best Calcium Supplement — calcium absorption and utilization depends on adequate K2 and D3; see how to optimize your bone health stack.
- Best Supplements for Joint Health — bone health is foundational to joint health; see the full picture.
- Vitamin D Dosage Guide — if you’re taking high-dose vitamin D3, K2 co-supplementation becomes particularly important.
Frequently Asked Questions
What is the difference between MK-7 and MK-4? MK-7 has a 72-hour half-life (once-daily dosing at 90–200 mcg). MK-4 requires high pharmacological doses (45 mg/day) to show fracture reduction benefits. For OTC supplementation, MK-7 is more practical and better supported.
Why is K2 important for bone health? K2 carboxylates osteocalcin, enabling it to bind calcium into bone matrix. Without K2, calcium absorbed from food or supplements may not be effectively incorporated into bone.
Should I take K2 with D3? Yes — D3 increases calcium absorption, while K2 ensures calcium goes to bone rather than soft tissues. The combination is rational and widely supported.
Does K2 conflict with blood thinners? Yes — vitamin K antagonizes warfarin and related anticoagulants. Never start K2 without physician guidance if on blood thinners.
What dose of MK-7 is effective for bone health? 90–200 mcg/day. The landmark Knapen 3-year RCT used 180 mcg/day and showed significant improvements in bone mineral density and reduced bone loss.
Frequently Asked Questions
- MK-7 (menaquinone-7) and MK-4 (menaquinone-4) are the two commercially important forms of vitamin K2. MK-7 has a much longer half-life in plasma (~72 hours vs. ~1–2 hours for MK-4), which means once-daily dosing at 90–200 mcg achieves sustained carboxylation of K2-dependent proteins. MK-4 requires much higher doses (typically 45 mg/day, 3x daily) to achieve therapeutic effects — the doses used in Japanese drug trials. For supplementation, MK-7 is more practical and better supported for bone health at low doses.
- Vitamin K2 is required as a cofactor to carboxylate osteocalcin — a protein produced by osteoblasts that binds calcium into bone matrix. Without adequate K2, osteocalcin remains uncarboxylated (ucOC) and cannot incorporate calcium into bone effectively. Elevated ucOC is a validated marker of K2 insufficiency and is associated with lower bone mineral density and increased fracture risk in epidemiological studies.
- The bone health evidence is strongest at 90–180 mcg/day of MK-7. A landmark 3-year RCT by Knapen et al. (2013) used 180 mcg/day of MK-7 and found significantly improved bone mineral density and reduced bone loss in postmenopausal women. The AI (Adequate Intake) for total vitamin K is only 90–120 mcg/day, but this refers to K1; most Western diets provide insufficient K2.
- Yes — this is the most important safety consideration. Vitamin K (all forms) is a cofactor in coagulation factor synthesis, which is precisely what warfarin (and related anticoagulants) inhibit. Taking K2 supplements while on warfarin can reduce the drug's effectiveness and destabilize INR. If you take warfarin or other vitamin K antagonists, do not start K2 supplementation without physician supervision.
- The D3/K2 combination is well-supported rationally: vitamin D3 increases calcium absorption from the gut, while K2 ensures that absorbed calcium is properly directed into bone matrix (via osteocalcin carboxylation) rather than soft tissues and arteries (via Matrix Gla Protein carboxylation). Several trials and epidemiological studies support the complementarity of these two nutrients for skeletal and cardiovascular health.