Vitamin K2 MK-4 (Menatetrenone): Short-Chain K2 for Bone & Tissue Health — A Research-Backed Guide
⚡ 60-Second Summary
Vitamin K2 MK-4 (menatetrenone) is the short-chain member of the K2 family — 4 isoprene units vs. MK-7's 7. It has a half-life of 1–4 hours, found primarily in animal-derived foods, and distributes to specific tissues (brain, testes, pancreas, arterial walls). The critical context for MK-4: it is used as a 45 mg/day prescription drug for osteoporosis in Japan (Glakay) — a dose supported by multiple RCTs showing significant fracture reduction. This is pharmacologic, not nutritional, dosing.
The dose gap matters enormously: Western supplement products typically contain 1–15 mg MK-4. Given the 1–4 hour half-life, once-daily doses in this range produce brief, transient K2 exposure that may not translate to the clinical benefits established at 45 mg in three divided daily doses. For sustained systemic K2 activity at typical supplement doses, MK-7 (72-hour half-life) is pharmacokinetically superior.
Warfarin interaction: MK-4 antagonizes warfarin — same principle as K1 and MK-7. Prescriber oversight required.
What is vitamin K2 MK-4?
Menaquinone-4 (MK-4) is a vitamin K2 form with a geranylgeranyl side chain — 4 isoprene units (20 carbons) — attached to the common 2-methyl-1,4-naphthoquinone ring of all vitamin K compounds. It is the shortest-chain menaquinone and is structurally closer to phylloquinone (K1) than to the long-chain menaquinones (MK-7 through MK-13).
Dietary sources: Unlike MK-7 (exclusively from bacterial fermentation and natto), MK-4 is found in animal-derived foods:
- Chicken dark meat and skin (the richest common food source at 60–70 µg/100 g)
- Egg yolks (content varies with hen diet — pasture-raised eggs have higher MK-4)
- Butter, ghee, hard cheeses
- Pork fat and organs
- Goose liver
Endogenous synthesis: Uniquely among menaquinones, MK-4 is produced by tissue-specific conversion from phylloquinone (K1) — a reaction involving side-chain cleavage and re-prenylation that occurs in brain, testes, pancreas, arterial wall, and other tissues. This means some MK-4 is present in tissues even in people eating no animal products, derived from dietary K1. The biological significance of this endogenous MK-4 production is an active area of research.
Evidence-based benefits of MK-4
1. Osteoporosis treatment — the 45 mg/day Japanese evidence base
The most rigorous clinical evidence for MK-4 comes from Japanese RCTs using 45 mg/day (15 mg three times daily with meals):
- Shiraki et al. (2000): 241 osteoporotic women randomized to MK-4 45 mg/day or no treatment for 24 months — MK-4 group showed significantly lower incidence of new vertebral fractures (13% vs. 28%, p<0.01)
- Multiple smaller trials confirm improvements in bone mineral density (BMD) and markers of bone turnover (osteocalcin carboxylation)
- A 2006 meta-analysis of 13 Japanese RCTs confirmed significant fracture reduction at 45 mg/day
At 45 mg/day (divided in three doses of 15 mg), MK-4 maintains sustained tissue exposure despite its short half-life. This pharmacological dosing produces genuine osteocalcin carboxylation and bone benefits. The 45 mg total daily dose is ~3,000–45,000 times higher than typical Western supplement MK-4 doses.
2. Vitamin K-dependent protein carboxylation in specific tissues
MK-4 shows preferential distribution to specific extrahepatic tissues including brain, testes, pancreas, and arterial walls — tissues where it activates local K-dependent proteins. This tissue specificity makes MK-4 important for functions beyond clotting and bone that K1 and MK-7 may not fully reach. Research on MK-4 in neurological function, insulin secretion, and arterial calcification is ongoing.
3. Arterial calcification prevention
MK-4 activates matrix Gla protein (MGP) in vascular smooth muscle cells, potentially inhibiting calcification. However, because of its short half-life, a single daily dose of low-dose MK-4 produces only transient MGP activation. At the 45 mg three-times-daily dose, sustained MGP activation is achieved. At typical supplement doses of 1–5 mg once daily, the calcification-prevention benefit is uncertain and likely inferior to MK-7 at 90–200 µg/day due to pharmacokinetics.
4. Anti-cancer and anti-proliferative effects (preclinical and emerging)
Several in vitro and animal studies show MK-4 inhibits proliferation of various cancer cell lines and induces apoptosis. A few small clinical studies in hepatocellular carcinoma patients show promising results with high-dose MK-4. This is an emerging area of research with insufficient clinical evidence for therapeutic recommendations.
Vitamin K adequacy and MK-4 role
Because the body converts K1 to MK-4 endogenously in multiple tissues, isolated MK-4 deficiency (without general vitamin K deficiency) is not a recognized clinical entity. General vitamin K deficiency — regardless of form — manifests as coagulopathy and bone issues. The specific question of whether optimizing MK-4 status above what diet provides offers additional benefit for tissue-specific functions is active research territory, particularly for brain aging and metabolic function.
MK-4 vs. MK-7 vs. K1 — key comparison
| Property | K1 (Phylloquinone) | K2 MK-4 (Menatetrenone) | K2 MK-7 (Menaquinone-7) |
|---|---|---|---|
| Source | Leafy greens, plant oils | Animal foods; converted from K1 in tissues | Natto; bacterial fermentation |
| Half-life | 1–2 hours | 1–4 hours | ~72 hours |
| Liver distribution | Primarily hepatic | Limited liver; specific extrahepatic tissues | Liver and broad extrahepatic |
| Bone evidence | Modest at nutritional doses | Strong at 45 mg/day (RCT); poor at 1–15 mg OTC | Strong at 90–200 µg/day (RCT) |
| Cardiovascular evidence | Limited | Emerging; dose-dependent | Strong (Rotterdam Study, mechanistic) |
| Once-daily dosing practicality | Requires daily dietary intake | 3x daily at 45 mg; single daily dose inadequate at low doses | Yes — 72h half-life supports once-daily |
How much MK-4 should you take?
- AI for all vitamin K forms: 90 µg/day (women); 120 µg/day (men) — not specific to any one form
- Japanese osteoporosis treatment dose: 45 mg/day (15 mg three times daily with meals) — medical supervision required; this is a pharmacologic drug dose in Japan (Glakay)
- Typical Western supplement dose: 1–15 mg/day — limited clinical evidence at these doses given rapid clearance; uncertain systemic benefit compared to MK-7 at 90–200 µg/day
- No established UL for vitamin K2 MK-4 in non-anticoagulated adults — no toxicity documented at any studied dose
If the goal is bone mineral density or arterial calcification prevention via once-daily supplementation, MK-7 at 90–200 µg/day has better pharmacokinetic rationale and stronger RCT evidence at that dose level. MK-4 at 45 mg/day under medical supervision is a legitimate evidence-based option for osteoporosis, particularly in countries where it is used therapeutically.
Safety and the warfarin interaction
MK-4 has an excellent safety record at all studied doses including 45 mg/day in long-term Japanese trials. No serious adverse effects have been attributed to MK-4 supplementation in published human studies at doses ranging from micrograms to 45 mg/day.
Warfarin interaction — critical
Like K1 and MK-7, MK-4 can overcome warfarin's anticoagulant effect by providing vitamin K substrate for clotting factor carboxylation. People on warfarin must not take MK-4 supplements without prescriber oversight and INR monitoring. The short half-life of MK-4 means that its warfarin interaction is more transient and dose-timing-dependent than MK-7, but it is still clinically significant. Any change in MK-4 supplementation by a warfarin patient requires anticoagulation management adjustment.
Drug and nutrient interactions
- Warfarin / vitamin K antagonists: As detailed above — significant clinical interaction; requires prescriber management.
- Orlistat and fat-malabsorption conditions: MK-4 is fat-soluble and requires dietary fat for absorption. Orlistat significantly reduces fat-soluble vitamin absorption; take MK-4 at least 2 hours from orlistat.
- Calcium supplements and vitamin D3: MK-4 (like MK-7) complements D3 by activating osteocalcin and MGP — the K-dependent proteins that D3 upregulates. The D3 + K2 combination rationale applies to MK-4 as well as MK-7.
- Broad-spectrum antibiotics (prolonged use): Eliminate gut bacteria that produce some menaquinones; may reduce overall K2 status.
Check our free interaction checker for additional combinations.
Who might benefit from MK-4
| Appropriate MK-4 use case | MK-7 likely superior alternative |
|---|---|
| Osteoporosis requiring pharmacologic K2 therapy (45 mg/day under physician supervision) | Adults wanting once-daily K2 supplementation for bone/cardiovascular benefit (MK-7 90–200 µg/day) |
| Research protocols specifically studying tissue-specific MK-4 effects | People with cardiovascular calcification concern (MK-7 has longer half-life and broader arterial distribution) |
| Supplement formulas that include multiple K2 forms for comprehensive coverage | Budget-conscious supplement users (MK-7 provides sustained coverage at much lower doses) |
| Brain health and neurological aging research contexts (MK-4 brain distribution is highest of K forms) | Anyone on warfarin without prescriber oversight for K2 supplementation |
Frequently asked questions
Is the MK-4 in my supplement actually doing anything?
At typical US supplement doses of 1–5 mg once daily, the clinical evidence is weak. MK-4's half-life of 1–4 hours means that most of the dose is cleared within 4–8 hours, leaving 16–20 hours per day of minimal systemic MK-4 exposure. The Japanese osteoporosis evidence required 15 mg three times daily to maintain meaningful tissue levels. If MK-4 is listed on your supplement label at 1–5 mg, the contribution to bone or cardiovascular protection is uncertain. MK-7 at 90–200 µg/day achieves more consistent coverage from a single daily dose.
Can I get enough MK-4 from food?
Dietary MK-4 from chicken, eggs, and dairy typically totals 10–100 µg/day — well below the 45 mg therapeutic dose. However, the body also converts dietary K1 (from leafy greens) to MK-4 in tissues, providing tissue-level MK-4 even without high dietary MK-4. This endogenous conversion meets basic tissue MK-4 needs in most adults with adequate K1 intake. For pharmacologic osteoporosis therapy, diet cannot provide sufficient MK-4.
Why don't US doctors prescribe 45 mg MK-4 for osteoporosis?
The 45 mg dose is approved in Japan as a prescription drug (Glakay/menatetrenone) but has not received FDA approval in the US as a drug. Bisphosphonates, denosumab, teriparatide, and romosozumab are the primary pharmaceutical osteoporosis treatments in the US. MK-4 at 45 mg is available as an off-label supplement in the US but is not standard of care. Some integrative medicine practitioners recommend it for appropriate patients.
Should I choose a K2 supplement with MK-4, MK-7, or both?
For sustained once-daily cardiovascular and bone support: MK-7 at 90–200 µg/day is the best-evidenced choice. For comprehensive tissue coverage across extrahepatic sites: some practitioners recommend combinations of MK-4 and MK-7. If pharmacologic osteoporosis therapy is the goal: MK-4 at 45 mg/day under medical supervision is an option with strong Japanese trial data. For most supplement users, MK-7 alone at 100–200 µg/day is the most practical, cost-effective choice.
Is MK-4 produced in the body from K1?
Yes — uniquely among menaquinones, MK-4 is produced endogenously in multiple tissues by conversion from dietary phylloquinone (K1). A side-chain cleavage reaction removes the phytyl chain and a geranylgeranyl chain is added, producing MK-4. This occurs in brain, testes, pancreas, arterial wall, and other tissues. The extent of this conversion and its physiological significance is still being characterized, but it means MK-4 is present in tissues even in vegans who eat no animal products and no fermented foods, provided they consume adequate K1 from leafy greens.
Related ingredients and articles
Vitamin K2 MK-7
The long-chain K2 with 72-hour half-life — the preferred once-daily K2 for bone and cardiovascular support.
Vitamin D3 + K2
The D3 and K2 synergy for calcium direction — relevant whether you choose MK-4 or MK-7.
Vitamin K1 (Phylloquinone)
The dietary K form that is converted to MK-4 endogenously and activates clotting factors.
Senior Multivitamin (50+)
K2 — in MK-4 or MK-7 form — is especially relevant in senior formulas for bone health.
Disclaimer: This information is for educational purposes only and should not replace medical advice. Always consult a qualified healthcare provider before starting any supplement, especially if you have a medical condition, are pregnant, or take prescription medications. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.