Vitamin K2 is sold in two forms that brands often treat as one ingredient — MK-4 and MK-7 — with different doses, different absorption and, in Japan, a regulatory history that includes a high-dose prescription medicine as well as food-form supplements.
This guide is for brand owners planning a vitamin K2 product made in Japan. It covers what the human trials show for each form, why the two are not interchangeable, a safety point on anticoagulant medication, and what to fix before asking for a quotation.
Health supplements are foods, not medicines, and are not a substitute for medical treatment. Nothing here is a claim that any product prevents, treats or cures a disease.
💬 Planning a vitamin K2 product made in Japan? We check the full formula against Japanese food law first. See Japan-made supplement OEM.
What the research shows
Randomised trials report bone-related benefits for both MK-7 at low, food-range doses and MK-4 at very high, pharmacological doses, and the two forms are absorbed differently, so a result for one is not evidence for the other.
| Study | Design | Reported result |
|---|---|---|
| Randomised, placebo-controlled trial, Calcified Tissue International 2020;106(5):476–485 (PMID 32060566) | 311 community-dwelling adults aged 50–75; MK-7 at 50 µg/day or 90 µg/day, with or without calcium and vitamin D3, for 1 year | 90 µg/day MK-7 significantly reduced femoral neck bone loss in postmenopausal women versus placebo; no significant effect seen in men; adding calcium and vitamin D3 gave no additional benefit |
| Randomised, placebo-controlled trial, Osteoporosis International 2007;18(7):963–972 (PMID 17287908) | 325 postmenopausal women; MK-4 (menatetrenone) 45 mg/day for 3 years | The MK-4 group maintained hip bone strength indices and femoral neck width relative to placebo, which declined; bone mineral density measured by DXA did not differ between groups |
| Comparative bioavailability study, Nutrition Journal 2012;11:93 (PMID 23140417) | Healthy Japanese women; single and repeated oral doses of MK-4 and MK-7 (420 µg single dose; 60 µg/day for 7 days) | MK-7 produced clear, sustained increases in serum vitamin K2 levels; MK-4 produced no detectable increase in serum levels at either dosing schedule |
Three points to keep in view:
- The doses are not comparable. The MK-7 trial used micrograms; the MK-4 osteoporosis trial used 45 mg/day — roughly a thousand-fold difference. Match your claim to the exact form and dose you cite.
- Absorption differs by form. The bioavailability study found oral MK-4 did not raise measurable blood levels at ordinary doses, while MK-7 did. This is a reason the two forms are formulated and dosed differently, not a reason to prefer one over the other.
- Outcome measures differed. The MK-7 trial measured bone loss by DXA at the femoral neck; the MK-4 trial measured bone strength indices and femoral neck width, and found no difference in DXA bone mineral density itself. Read what was actually measured before citing either trial.
Checked against the published abstracts on 25 September 2026.
A note on MK-4 and Japanese drug regulation
In Japan, MK-4 (menatetrenone) is also used as a prescription medicine at a dose far higher than any food-form supplement, for a bone-density-related indication in postmenopausal women.
The 45 mg/day dose in the trial above is the same order of dose used in Japan’s approved prescription form of menatetrenone — thousands of times the amount used in a typical MK-7 food supplement. This does not mean food-form MK-4 or MK-7 supplements are medicines; it means the specific high-dose, prescription-only use of MK-4 in Japan is a separate matter from the vitamin K2 sold as a food ingredient. Keep any supplement’s MK-4 dose clearly in the food-supplement range, and do not describe a supplement using language associated with the prescription product or its approved use.
💬 Need an evidence summary for your regulatory adviser that keeps the food-supplement dose clearly separate from the pharmaceutical dose? We prepare it with the manufacturing documents. Tell us your market.
What Japanese products say
Japan operates a Foods with Nutrient Function Claims system that allows a standard, pre-set function wording for vitamin K when a product’s content falls within a defined daily intake range, without individual notification.
Unlike the Foods with Function Claims system used for many other ingredients in this guide series, the Nutrient Function Claims system applies fixed wording and a fixed intake range set by the government, rather than evidence submitted by each business. Confirm the current intake range and exact wording for vitamin K directly with your regulatory adviser before finalising a label, since these figures are set by government notice and are the kind of detail that should be checked against the current text rather than assumed.
A note on anticoagulant medication
Vitamin K is well documented to reduce the effect of warfarin and similar anticoagulant medications, so products containing vitamin K in any form should carry guidance for people on this kind of medication to consult a doctor.
A controlled trial found that even a modest daily amount of vitamin K1 from a multivitamin reduced the anticoagulant effect of warfarin in patients with low vitamin K status, to the point of needing a warfarin dose adjustment. Vitamin K2 acts through the same coagulation pathway as vitamin K1. This is standard, well-established pharmacology, not a disease claim, and is why vitamin K products commonly carry advice for people on anticoagulant medication to speak to a doctor before use.
Wording that stays on safe ground
Name the form and dose you are describing, and never suggest a supplement matches the prescription-grade use of MK-4.
| Safer wording | Wording to avoid |
|---|---|
| ”Contains 90 mcg MK-7 per serving, studied for bone-related markers” | Any dose or wording that echoes the 45 mg/day prescription use of MK-4 |
| ”MK-4 and MK-7 are absorbed differently” | Implying the two forms are interchangeable or equally studied |
| ”Consult a doctor if taking anticoagulant medication” | Silence on the warfarin interaction |
How vitamin K2 is formulated
MK-7 is dosed in micrograms and MK-4 in milligrams within food-supplement ranges, so the two forms suit different formats and different companion ingredients.
| Dosage form | Why brands choose it | What to weigh up |
|---|---|---|
| Softgel or oil-based capsule | Vitamin K2 is fat-soluble; an oil base can aid absorption | Pairs naturally with vitamin D3 |
| Hard capsule or tablet | Simple, low cost per serving | Confirm stability of the chosen K2 form during storage |
| Combined bone-health formula | Paired with calcium, vitamin D or magnesium | Each companion ingredient needs its own check against Japanese food law |
Decisions that shape the specification:
- Form. Choose MK-4 or MK-7 deliberately, and cite only the evidence for the form you use.
- Source. MK-7 for foods is commonly produced by fermentation; MK-4 used in foods is typically produced synthetically at food-supplement doses, distinct from the pharmaceutical-grade product. Ask the supplier for the production method and confirmed content.
- Amount per serving. Keep the amount within a food-supplement range, and match it to the study you intend to cite.
- Anticoagulant labelling. Decide, with your regulatory adviser, what warning or consultation advice your market expects for a vitamin K product.
- Companion ingredients. Calcium and vitamin D are common partners in bone-related formulas. Each needs its own check against Japanese food law.
The check that comes first
Every ingredient must be permitted in foods in Japan, or a Japanese factory cannot make the product.
Vitamin K2 in food-supplement form and dose is established in Japanese foods; the high-dose prescription use of MK-4 is a separate, medicine-only matter that a food-form product must stay well clear of. See the Japan-made supplement OEM page, and compare with our vitamin D and calcium guides if you plan a combined bone-related formula.
Before you ask for a quotation
A factory can quote accurately once the form, the amount, the companions and the packaging are fixed.
- MK-4 or MK-7, and the amount per serving
- Dosage form
- Companion ingredients and their amounts
- Anticoagulant-medication labelling requirements in your markets
- Packaging
- Countries you will sell in, and first order and annual volume
💬 Ready to design a Japan-made vitamin K2 product? Send us the concept — form, amount, companion ingredients and the countries you will sell in.
Frequently asked questions
1. What is the difference between MK-4 and MK-7?
They are absorbed differently: a bioavailability study found MK-7 raised blood vitamin K2 levels while ordinary oral doses of MK-4 did not. They are also dosed very differently — MK-7 in micrograms, MK-4 (in its pharmaceutical use) in tens of milligrams. Treat them as separate ingredients with separate evidence.
2. Is vitamin K2 the same as the menatetrenone drug used in Japan?
No, not at food-supplement doses. Japan also uses MK-4 (menatetrenone) as a prescription medicine at a much higher dose for a bone-density-related indication. A food-form supplement should stay clearly within food-supplement dose ranges and avoid language associated with the prescription product.
3. Does vitamin K2 affect blood-thinning medication?
Yes. Vitamin K reduces the effect of warfarin and similar anticoagulants. A controlled trial found even a modest vitamin K1 dose reduced warfarin’s effect in patients with low vitamin K status. Products should carry guidance for people on anticoagulant medication to consult a doctor.
4. How is vitamin K2 usually formulated?
As a softgel or capsule, often paired with vitamin D3, since all are fat-soluble. MK-7 for foods is commonly produced by fermentation.
5. What wording should I avoid?
Avoid any dose or phrasing that echoes the high-dose prescription use of MK-4, and avoid presenting MK-4 and MK-7 as interchangeable or equally studied.
Sources: “Effect of Low-Dose Vitamin K2 Supplementation on Bone Mineral Density in Middle-Aged and Elderly Chinese”, Calcified Tissue International 2020;106(5):476–485 (PMID 32060566); “Vitamin K2 supplementation improves hip bone geometry and bone strength indices in postmenopausal women”, Osteoporosis International 2007;18(7):963–972 (PMID 17287908); “Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women”, Nutrition Journal 2012;11:93 (PMID 23140417); “Over-the-counter vitamin K1-containing multivitamin supplements disrupt warfarin anticoagulation in vitamin K1-depleted patients. A prospective, controlled trial”, Thrombosis and Haemostasis 2004 (PMID 15543329); Consumer Affairs Agency Foods with Nutrient Function Claims system. Checked on 25 September 2026.