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 effects on some bone-related measures for vitamin K2 at low, food-range doses and for 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 Chinese men and postmenopausal women aged 50–75; vitamin K2 (listed by the authors as menaquinone-7) at 50 µg/day or 90 µg/day, or 90 µg/day with calcium and vitamin D3, versus placebo for 1 year | Femoral neck bone loss was significantly lower in postmenopausal women in the two 90 µg groups than with placebo; no effect 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 apparently healthy postmenopausal women aged 55–75 in the Netherlands; MK-4 (menatetrenone) 45 mg/day, a pharmaceutical-level dose, or placebo for 3 years; the MK-4 and a research fund were supplied by a pharmaceutical company that makes menatetrenone | MK-4 did not affect DXA bone mineral density, but bone mineral content and femoral neck width increased relative to placebo; hip bone strength stayed unchanged in the MK-4 group while it decreased significantly in the placebo group |
| Comparative bioavailability study, Nutrition Journal 2012;11:93 (PMID 23140417) | Two small randomised studies in healthy Japanese women aged 20–21, each with 10 participants (5 per group): a single 420 µg dose, and 60 µg/day for 7 days, of MK-4 or MK-7; one author is employed by the company that prepared the test materials | MK-7 was well absorbed and detected in serum up to 48 hours after a single dose, and 7 days of MK-7 raised serum MK-7 in all subjects; MK-4 was not detectable after the single dose and did not raise serum MK-4 after 7 days |
Three points to keep in view:
- The doses are not comparable. The low-dose trial used 50–90 µg/day; the MK-4 trial used 45 mg/day — roughly 500 to 900 times more. 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 nutritional doses, while MK-7 did. With only 5 people per group and an author from the material supplier, it is a small study; it is a reason the two forms are formulated and dosed differently, not proof that one is better.
- Outcome measures and populations differed. The low-dose trial measured bone loss by DXA at the femoral neck in Chinese adults; the MK-4 trial, funded in part by a pharmaceutical company, found no difference in DXA bone mineral density and reported changes in bone mineral content, femoral neck width and calculated strength indices instead. Read what was actually measured before citing either trial.
Checked against the published abstracts on 13 October 2026.
A note on MK-4 and Japanese drug regulation
In Japan, MK-4 (menatetrenone) is also used as a prescription medicine for a bone-related indication, at a dose far higher than any food-form supplement.
The 45 mg/day dose in the trial above is the same order of dose used in Japan’s approved prescription form of menatetrenone — hundreds of times the 50–90 µg used in the low-dose trial above. 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’s Foods with Nutrient Function Claims system lets a product whose daily amount of vitamin K is 45–150 µg use two fixed function sentences, together with a mandatory caution for people taking anticoagulant medicine.
Unlike the Foods with Function Claims system used for many other ingredients in this guide series, the Nutrient Function Claims system is self-certified: nothing is notified to the government and there is no individual review, but the intake range and the wording are fixed in Appendix 11 of the Food Labeling Standards and cannot be altered. The standard was revised with effect from 1 October 2026. For vitamin K the range stayed at 45–150 µg a day, and the wording became (our translation of the official Japanese):
- “Vitamin K is one of the nutrients that help build bone.” (ビタミンＫは、骨を作るのを助ける栄養素のひとつです。)
- “Vitamin K is a nutrient that helps normal blood clotting.” (ビタミンＫは、正常な血液凝固を助ける栄養素です。)
The mandatory caution, unchanged by the revision, is: “This product does not cure disease or further promote health through excessive intake. Follow the daily recommended amount. People taking blood anticoagulant medicine should avoid this product.”
Before the revision there was only one sentence: “Vitamin K is a nutrient that maintains normal blood-clotting ability.” The bone sentence is new. Processed foods manufactured, processed or imported by 31 March 2030 may still follow the previous standard; a new product is best designed to the revised wording. A product above 150 µg of vitamin K a day cannot use this wording.
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. In Japan, a vitamin K product using the nutrient-function wording must state that people taking anticoagulant medicine should avoid it; outside that system, 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
In food supplements both MK-4 and MK-7 are used at microgram amounts — only the prescription use of MK-4 is in milligrams — and the two forms are absorbed differently, so the form has to be fixed before the amount.
| 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. To use Japan’s nutrient-function wording, the daily amount of vitamin K must be 45–150 µg.
- 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. Food supplements use both in micrograms, while the pharmaceutical use of MK-4 is 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 25 µg daily vitamin K1 dose in a multivitamin reduced warfarin’s effect in patients with low vitamin K status. In Japan, a product using the nutrient-function wording must tell people taking anticoagulant medicine to avoid it; elsewhere, products should at least carry guidance 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, PMC1915640); “Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women”, Nutrition Journal 2012;11:93 (PMID 23140417, PMC3502319); “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, Food Labeling Standards Appendix 11 as revised with effect from 1 October 2026 (food_labeling_cms201_261001_02.pdf, caa.go.jp); Consumer Commission food labeling subcommittee, material 2 of 6 August 2026 on the revision of Foods with Nutrient Function Claims (260806_shiryou2.pdf, cao.go.jp). Checked on 13 October 2026.