Vitamin K2 (menaquinone-7, MK-7)
menaquinone-7, C46H64O2
Vitamin KIngredient formSources last checked: October 15, 2026
Medical & Industry Advisor: Dr. James Pendleton, ND
Answer
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- Open market
What it is
- Vitamin K2 is a series of menaquinones, named MK-4 through MK-13 by the length of their side chain. PubChem's record for menaquinone-7 (MK-7, C46H64O2, molecular weight 649.0) is the all-trans isomer: its systematic name gives every double bond in the side chain the trans (E) configuration. Cis isomers of MK-7 have the same formula and mass. [NIH Office of Dietary Supplements, Vitamin K fact sheet][PubChem compound properties][Szterk et al., Molecules 2018]
Forms compared
How vitamin K2 (MK-7) compares with related forms on a spec sheet and a label.
| Form | Declared on the label as | Content | Identity check |
|---|---|---|---|
| Menaquinone-7 (MK-7), all-trans | Vitamin K (as menaquinone-7) | C46H64O2, molecular weight 649.0; made by natto fermentation or by chemical synthesis[PubChem compound properties, 2026-10-15][Szterk et al., Molecules 2018, 2026-10-15] | All-trans MK-7 as a percentage, with total MK-7 and MK-6, by an HPLC method that separates cis and trans isomers |
| Menaquinone-4 (MK-4, menatetrenone) | Vitamin K (as menaquinone-4) | C31H40O2, molecular weight 444.6; a shorter side chain than MK-7[PubChem compound properties, 2026-10-15][NIH Office of Dietary Supplements, Vitamin K fact sheet, 2026-10-15] | The compound named on the CoA: menaquinone-4, not menaquinone-7. NIH lists both as vitamin K2 forms used in supplements |
| Vitamin K1 (phylloquinone; phytonadione is the synthetic form) | Vitamin K (as phylloquinone) or Vitamin K (as phytonadione) | C31H46O2, molecular weight 450.7[PubChem compound properties, 2026-10-15][NIH Office of Dietary Supplements, Vitamin K fact sheet, 2026-10-15] | The compound named on the CoA. K1 and K2 forms are declared under the same nutrient name, vitamin K |
On the Supplement Facts label
The Supplement Facts panel declares vitamin K in mcg against a Daily Value of 120 mcg for adults and children age 4 and older. The source may be named in parentheses, for example Vitamin K (as menaquinone-7); a source not named in the panel goes in the ingredient statement below it. Vitamin K1 and the K2 forms share the nutrient name vitamin K, so the source is where the form appears.[NIH Office of Dietary Supplements, Vitamin K fact sheet, 2026-10-15][21 CFR 101.36(d), 2026-10-15]
Spec parameters buyers should demand
What to ask for on the certificate of analysis and spec sheet. Identity, quality, and regulatory parameters only. This is not advice about efficacy.
| Parameter | What to ask | Why it matters |
|---|---|---|
| All-trans MK-7 share | Ask for all-trans MK-7 as a percentage, with total MK-7 and MK-6, on the raw-material CoA and at finished-product release, measured by an HPLC method that separates cis and trans isomers. Name the method on the spec.[Orlando et al., Molecules 2019][Szterk et al., Molecules 2018] | Cis and trans isomers of MK-7 have the same mass, and a 2019 study reports that conventional chromatographic methods cannot tell several cis-trans isomers apart from the all-trans form, which risks overestimating it. |
| Source | State on the spec whether the MK-7 is made by natto fermentation or by chemical synthesis, and keep the isomer test either way.[Lal et al., Bioprocess and Biosystems Engineering 2022][Szterk et al., Molecules 2018] | Fermentation can also produce cis isomers, and a 2018 survey found cis/trans MK-7 isomers in a product labeled as made from natto, so the source statement does not replace the test. |
| Blends with minerals | If MK-7 shares a capsule or tablet with magnesium oxide, other alkaline minerals or arginine, ask for a stability study on the finished blend at your storage conditions.[Orlando et al., Molecules 2019] | In 12-month and accelerated 6-month stability tests, MK-7 raw materials blended with magnesium oxide or arginine degraded, while calcium salts were generally more stable; results differed between raw materials. |
| Content uniformity | Ask for content uniformity data on the finished product. At a raw-material strength of 2,000 ppm (2 mg MK-7 per g, the strength of the three powders in a 2019 stability study), 120 mcg, the Daily Value, takes 60 mg of powder.[Orlando et al., Molecules 2019][NIH Office of Dietary Supplements, Vitamin K fact sheet] | The vitamin is a very small share of each unit's fill, so blending, not capsule space, is the manufacturing risk. |
| End-of-shelf-life assay | Ask for all-trans MK-7 at the end of shelf life, not only at release.[Orlando et al., Molecules 2019][Szterk et al., Molecules 2018][21 CFR 101.9(g)(4)(i)] | MK-7 can be degraded by UV light and alkaline compounds and can fall during storage, and an added vitamin must still meet its declared value. |
| Identity verification | Confirm the manufacturer runs at least one appropriate identity test on each incoming lot, as 21 CFR 111.75(a)(1) requires for every dietary ingredient unless FDA has granted a petition exemption, and that the CoA names menaquinone-7, not menaquinone-4 or phylloquinone.[21 CFR 111.75(a)(1)] | Vitamin K1 and the K2 forms are declared under the same nutrient name, so the compound on the CoA is how a buyer tells them apart. |
QC and testing considerations
- Test all-trans MK-7 in the finished product as well as in the raw material: a 2018 study names UV light and oxidation during processing and storage as routes by which cis isomers can form. [Szterk et al., Molecules 2018]
- A raw-material CoA does not describe a blend: when MK-7 shares a unit with minerals, the stability data has to come from that blend. [Orlando et al., Molecules 2019]
Further reading: How to read a certificate of analysis and third-party supplement testing.
Published market surveys
Totals as each study reports them: what was measured, how many products, and the result. Methods and sampling differ between studies.
| Measured | Study | Market, products tested | Result | Funding or affiliation |
|---|---|---|---|---|
| Content vs label | Szterk et al., Molecules 2018 | Poland (bought in pharmacies; 4 tablets and 4 oil softgels, made in several European countries), n=8 | All-trans MK-7 measured below the declared amount in 4 of 8 products, at 23% to 88% of the label; the other 4 measured above it. | Independent |
| Isomer | Szterk et al., Molecules 2018 | Poland (bought in pharmacies; 4 tablets and 4 oil softgels, made in several European countries), n=8 | Cis/trans MK-7 isomers were found in 2 of 8 products, in both at more than the all-trans MK-7 content; 1 of the 2 was labeled as made from natto. | Independent |
Government statements, quoted
Several forms of vitamin K are used in dietary supplements, including vitamin K1 as phylloquinone or phytonadione (a synthetic form of vitamin K1) and vitamin K2 as MK-4 or MK-7 [18].
The FNB did not establish ULs for vitamin K because of its low potential for toxicity [3]. In its report, the FNB stated that "no adverse effects associated with vitamin K consumption from food or supplements have been reported in humans or animals."
Vitamin K can have a serious and potentially dangerous interaction with anticoagulants such as warfarin (Coumadin) as well as phenprocoumon, acenocoumarol, and tioclomarol, which are commonly used in some European countries [7,8]. These drugs antagonize the activity of vitamin K, leading to the depletion of vitamin K-dependent clotting factors. People taking warfarin and similar anticoagulants need to maintain a consistent intake of vitamin K from food and supplements because sudden changes in vitamin K intakes can increase or decrease the anticoagulant effect [45].
Reference list
- NIH Office of Dietary Supplements, Vitamin K Health Professional Fact Sheet (updated March 29, 2021) Government reference
- 21 CFR 101.36: Nutrition labeling of dietary supplements Regulatory
- 21 CFR 101.9(g): compliance classes and label-value requirements Regulatory
- 21 CFR 111.75: identity testing of dietary ingredients Regulatory
- PubChem compound records: menaquinone-7 (CID 5287554), menatetrenone (CID 5282367), phylloquinone (CID 5284607) Government reference
- Szterk et al., menaquinone-7 content and impurities in oil and non-oil dietary supplements, Molecules 2018;23(5):1056 Market survey
A reference list is not claim substantiation. Under the FTC's Health Products Compliance Guidance (December 2022), marketing claims about a finished product require competent and reliable scientific evidence, typically randomized, controlled human clinical testing. Responsibility for substantiating product claims rests with the brand.
Manufacturers with stated capability
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Further reading
The decision framework behind this reference: five checkable criteria for choosing between a branded ingredient and its generic form.
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