Vitamin K2 Supplements: How to Compare MK-4, MK-7, Amounts, and Labels

Vitamin K is a fat-soluble vitamin that exists in several forms. Vitamin K1 (phylloquinone) is found primarily in green leafy plants, while vitamin K2 (menaquinone) comprises a family of related compounds identified by the length of their side chain — MK-4, MK-7, and others. A vitamin K2 supplement usually declares a specific menaquinone form and an amount per serving stated in micrograms (mcg or µg).

A reliable supplement comparison rests on a handful of declared facts rather than a single headline figure. Before looking at price, establish what each vitamin K2 label actually says about the amount it delivers, which menaquinone form it names, how it is formulated, and how well that information is documented. Government dietary references describe how much vitamin K people generally need from all sources combined — food and supplements together — and those references are a useful backdrop, not a product recommendation. (NIH Office of Dietary Supplements) This guide does not recommend a form, brand, product, or dose for any health outcome — it shows you how to read a vitamin K2 label so you can compare products on the facts that are actually declared.

The sections below move through each field in the order it affects a comparison, from the menaquinone form and the vitamin K2 amount through to price, and end with a practical checklist and the point at which a label gives you too little to compare meaningfully. For the broader framework that applies to every category, see How to Compare Supplements.

The two menaquinone forms you will most often see on a vitamin K2 label are MK-4 and MK-7. They are both vitamin K2, but they differ in the length of their molecular side chain, and that difference is a labeling and formulation fact — not, on its own, a verdict on which product is better.

• MK-4 (menaquinone-4) — a shorter-chain menaquinone. It is the form found in some animal foods and is also produced in the body from other vitamin K forms. Where a label names MK-4, that is an attributed disclosure fact to compare.
• MK-7 (menaquinone-7) — a longer-chain menaquinone commonly derived from bacterial fermentation (for example from natto, a fermented soy food). Where a label names MK-7, that is an attributed disclosure fact to compare.

This guide does not declare MK-4 or MK-7 universally superior. Studies comparing the two forms have examined different outcomes, doses, and populations, and findings vary; no form is established here as better for any health outcome. A form name identifies the chemistry; it does not, by itself, establish dose, quality, suitability, or any result. Two products that share the same named form can still differ in every other respect — vitamin K2 amount per serving, serving size, additional ingredients, and documentation.

What to look for on the label instead of stopping at the form name:

• Whether the label names a single menaquinone form or a blend of contributing vitamin K2 forms. A blend means the declared vitamin K2 amount may come from more than one compound.
• Whether the named form is paired with an explicit vitamin K2 amount declaration. The name identifies the chemistry; the microgram figure is what you compare on.
• Whether the form name is used alongside marketing language such as “high absorption,” “optimal ratio,” or “clinically studied,” which is not independently defined or regulated and is not proof of superior effectiveness.

For the full category context — what each form name does and does not tell you — see the Vitamin K2 decision hub.

The number that matters most on a vitamin K2 label is the declared vitamin K2 amount per serving, usually stated in micrograms (mcg). Vitamin K2 amounts vary across products — commonly from tens to a few hundred micrograms per serving — so a larger headline number does not automatically mean a stronger or better product.

Read the vitamin K2 amount in a single consistent unit so two products are measured the same way. Where a label declares both a compound amount and an explicit vitamin K2 (menaquinone) amount, the vitamin K2 amount is the comparable quantity. The FDA’s Dietary Supplement Labeling Guide describes the convention that the Supplement Facts panel identifies the form and declares the amount per serving. (FDA Dietary Supplement Labeling Guide)

The vitamin K2 amount only becomes comparable once you know what constitutes a serving. Two products can declare the same microgram amount while requiring very different numbers of capsules, tablets, or drops to reach it.

• Serving size — how many capsules, tablets, softgels, or drops the declared amounts refer to (one softgel, two capsules, one dropper).
• Servings per container — how many servings the package holds, which sets the total vitamin K2 in the container and the cost per serving.

Read these two fields together with the vitamin K2 amount. A product that delivers 100 mcg per one-softgel serving is not directly comparable to one that delivers 100 mcg per two-softgel serving, even though the microgram figure matches — the serving structure changes how the product fits into a daily routine and how long a container lasts.

Note any product that lists vitamin K2 only inside a proprietary blend, where the individual amount is not visible. A label that does not declare the vitamin K2 amount per serving cannot be placed on the same scale as one that does — and the honest response is to recognize that gap rather than estimate a figure.

These names describe how vitamin K2 is identified and presented on a label. Where a form or term is documented on a label, that is an attributed disclosure fact to compare. This guide does not invent bioavailability or absorption comparisons and does not treat any form as universally superior.

• Vitamin K2 / menaquinone — the family name for the vitamin K2 compounds. On a Supplement Facts panel, “vitamin K2” or “menaquinone” identifies the ingredient. This guide does not treat the ingredient name alone as a potency or effectiveness claim.
• MK-4 and MK-7 — the specific menaquinone forms most commonly declared, as described above. Compare the declared amount alongside the named form, not the form name alone.
• All-trans vs other isomer language where documented — some labels describe the isomeric form of MK-7 (for example “all-trans MK-7”). Where documented, that is an attributed disclosure fact to compare. This guide does not invent isomer comparisons or treat any isomer description as proof of superior effectiveness.
• Source language where documented — terms such as “natto-derived,” “fermented,” or “synthetic” describe the documented source of the menaquinone. Where documented, that is an attributed disclosure fact to compare. This guide does not invent sourcing data or treat a source description as a quality verdict.
• “High absorption,” “optimal ratio,” “clinically studied” — marketing terms sometimes used on vitamin K2 labels. These are not independently defined or regulated claims, and this guide does not treat them as proof of superior effectiveness or health outcomes. Where a product cites a specific study or a named third-party test, that is recorded as an attributed disclosure fact — not silently upgraded into a quality ranking.

Many vitamin K2 supplements are sold as D3 + K2 combination products, pairing vitamin D3 (cholecalciferol) with a menaquinone form in a single softgel or capsule. This is a formulation and comparison consideration — not an endorsement of combination products over standalone vitamin K2.

When you compare a D3 + K2 product against a standalone vitamin K2 product:

• Compare the vitamin K2 amount, not the combined “vitamin” total. A D3 + K2 label declares vitamin D3 and vitamin K2 as separate line items. The comparable vitamin K2 quantity is the declared menaquinone amount per serving, not a summed figure across both vitamins.
• Note the vitamin D3 amount as a separate field. If you are also comparing vitamin D intake, read the declared D3 amount alongside the K2 amount. The two vitamins are distinct ingredients with their own declared amounts; do not collapse them into one number.
• A combination product is a different formulation. It is not a stronger version of the same vitamin K2. Compare the declared K2 amount, the named menaquinone form, the serving size, and the full ingredient list together.

This guide does not claim that D3 + K2 combinations are superior to standalone vitamin K2, or that any particular D3-to-K2 ratio is optimal. For the category context on vitamin D3, see the Vitamin D decision hub.

The Supplement Facts panel lists the active vitamin K2 (and vitamin D3 where present), but the full label also includes an “Other ingredients” section. Reading it is part of a fair comparison, because formulation transparency affects how much you can actually verify about a product.

• Additional vitamin K forms — any other vitamin K compounds (including vitamin K1) that may contribute to a declared “vitamin K” total, and whether they are declared plainly or buried in a blend.
• Carriers, oils, and excipients — vitamin K2 is fat-soluble, so softgel products often list a carrier oil (such as MCT, olive, or sunflower oil). The carrier is part of the formulation, not part of the vitamin K2 amount.
• Fillers, binders, and excipients — the non-active ingredients that make up the capsule, tablet, or softgel.
• Allergen and additive disclosure — whether the label clearly states what else is present, which matters for people avoiding specific ingredients (for example soy-derived carriers).

A label that declares its full formulation plainly is easier to compare than one that leaves the “Other ingredients” section vague. More added ingredients are not automatically better. Transparency is not a quality verdict on its own, but it is one of the fields that make a meaningful comparison possible. Missing or vague disclosure is reported as unavailable, not silently treated as a failure or a pass.

A label states what a manufacturer says is in a product. Verification is a separate question: whether an independent party has tested or certified the product, and how clearly the manufacturer documents its sourcing and standards.

• Third-party testing or certification — whether the product carries documented independent verification (for example from a program such as USP). (USP)
• Who is making the claim — a third-party certification is recorded differently from a manufacturer or retailer claim. HerbParlor records testing and certification as attributed rather than independently confirming it.
• Manufacturer and market transparency — the brand, the market the product is sold in, and how clearly the company documents what is in the product.
• Source provenance — where each fact comes from (manufacturer, retailer, regulator, or lab report), kept distinct from editorial analysis.

When you compare vitamin K2 supplements, treat verification as one field among several — not as a tiebreaker that overrides the declared vitamin K2 amount and serving structure. A well-documented product is easier to evaluate, but documentation does not by itself establish effectiveness or suitability for any individual.

To check what testing and certification information is actually documented for a product, use the Testing Checker.

Beyond the active ingredient and testing, a fair comparison also weighs how clearly a product’s origin and documentation are disclosed. HerbParlor evaluates this across several dimensions:

• Named manufacturer — a clearly stated brand and manufacturer, rather than an unnamed or white-label listing.
• Market and country of sale — where the product is sold, which affects labeling conventions and the regulatory context the label follows.
• Documented source of the menaquinone — where stated, the source of the vitamin K2 (for example fermented or natto-derived for MK-7). Where documented, that is an attributed disclosure fact; where it is not stated, it is reported as unavailable rather than guessed.
• Source provenance of the facts — whether each piece of information comes from the manufacturer, a retailer, a regulator, or a lab report, kept separate from editorial analysis.

Products that disclose more are easier to compare; products that disclose less are reported as such, not ranked against them. Transparency is a field that makes comparison possible — not, on its own, a quality verdict.

Price only becomes meaningful once it is placed next to what a product actually delivers. A lower sticker price is not automatically a better value if the container holds fewer servings or declares less vitamin K2 per serving.

Two honest ways to compare cost:

• Price per serving — divide the product price by the number of servings in the container. This puts products on a common per-serving scale regardless of package size.
• Standardized value — HerbParlor’s VitaValue™ places price next to a standardized vitamin K2 quantity, derived only from the explicitly declared amount. It reports an honest “unavailable” or “needs review” status where the declared information does not support a calculation, rather than inventing a figure.

This guide does not invent prices, conversions, or value figures. Where a label does not declare the vitamin K2 amount and no existing normalization rule applies, the honest status is “needs review” — not a guessed cost per unit. Use the Supplement Value Calculator to see standardized value where the declared information supports it.

VitaValue™ is a standardized cost / value calculation. It is not an effectiveness score and not a quality score. A lower standardized cost means a product delivers the declared vitamin K2 amount at a lower price per normalized unit — nothing more. It says nothing about how well the product is documented or verified; that is what the transparency and verification steps are for.

Run through this checklist for each product before you compare them side by side. It keeps every label on the same scale and surfaces the gaps that make a comparison unreliable.

Once each product answers these questions, you can place them side by side in the vitamin K2 comparison view and inspect a specific label field by field with the Analyze a Label tool.

Sometimes a label or retailer listing simply does not declare enough to compare fairly. A product that names the form but gives no vitamin K2 amount, no serving size, or no servings-per-container figure cannot be placed on the same scale as a fully declared product — and the honest response is to recognize that limit rather than fill the gap with a guess.

Signs that a comparison may not be meaningful:

• No vitamin K2 amount is declared, and no existing normalization rule applies.
• The serving size or servings per container are missing or ambiguous.
• A D3 + K2 product declares only a combined “vitamin” total without separating the vitamin D3 and vitamin K2 amounts.
• The label names a blend without disclosing the contributing forms or their proportions.
• Testing, manufacturer, or source information is absent to the point that nothing can be verified.

Missing information is not automatically evidence of a product problem — it means the comparison quantity is not currently declared. HerbParlor reports such cases as “needs review” rather than estimating a value, and a product in that state should be compared cautiously, with the gap made explicit.

Once you can read a vitamin K2 label for what it does and does not declare, HerbParlor’s comparison and analysis tools let you apply that literacy directly. The primary next step is the vitamin K2 comparison view; the secondary links help you inspect a specific label, evaluate standardized value, check testing documentation, and review the evidence behind claims.

More HerbParlor reading that pairs with this guide:

• Vitamin K2 Supplements: Compare Forms, Labels & Value — the full decision hub for the vitamin K2 category.
• Vitamin D Supplements — the decision hub for vitamin D, useful when comparing D3 + K2 combination products.
• How to Compare Supplements — the general label-to-value framework behind every HerbParlor comparison.
• Compare Supplements — place records from any category next to each other.