MK-7 vs. MK-4: Which Vitamin K2 Form I Recommend and Why

Walk into any supplement aisle or search “vitamin K2” and you’ll find two forms sitting side by side — MK-4 and MK-7 — usually with a label that tells you nothing about why one might matter more than the other for your goals. Most articles on this topic just list both forms and their food sources and call it a day. I want to give you something more useful: which one I actually reach for in practice, and the specific reasoning behind it.

I’ve been taking vitamin K2 myself for more than a decade specifically to support my bones, my heart, and — as I’ve written about before — the health of other organs that depend on properly directed calcium. I’ve also written extensively about K2 across nearly every system it touches: arterial calcification and atherosclerosis prevention, general heart health, colon and gut health, children’s bone development, and the sheer scope of how common K2 deficiency actually is. This post pulls that body of work together to answer the one question I get asked most: MK-7 or MK-4?

Both are legitimate forms of vitamin K2. They are not interchangeable, and the confusion around them comes down to one core issue: pharmacokinetics — how long each form actually stays active in your body.

The Core Difference — Half-Life and Dosing Frequency

MK-4 (menaquinone-4) is a short-chain form of vitamin K2 with a half-life of roughly one to eight hours, depending on the source you consult. It clears the bloodstream quickly, which is why it doesn’t accumulate to meaningfully elevate serum K2 levels at nutritional doses even after repeated dosing.

MK-7 (menaquinone-7), the long-chain form most commonly derived from fermentation (natto is the classic dietary source), behaves very differently. Its longer isoprenoid side chain makes it more lipophilic and far more efficiently reabsorbed as it circulates, giving it a half-life in the range of 68 to 72 hours — roughly three days according to pharmacokinetic comparisons. In a head-to-head trial giving healthy women 60 mcg/day of each form for a week, MK-7 raised serum vitamin K2 levels significantly, while MK-4 did not budge from baseline.

Here’s why that matters clinically, not just academically:

• MK-4 needs to be dosed in the milligram range, often multiple times a day, to maintain any meaningful blood level.
• MK-7 is effective at microgram doses (typically 90–200 mcg), taken once daily, because it stays circulating long enough to build a steady state.

That thousand-fold dosing gap isn’t a marketing quirk — it’s the direct consequence of how differently these two molecules are handled once they’re absorbed. It’s also part of why K2 deficiency is so widespread in the first place — I go into the scope of that problem, across age groups and regions, in my post on vitamin K2 deficiency as a global health problem.

What the Research Actually Shows for Each

This is where the two forms genuinely diverge — not just in pharmacokinetics, but in what they’ve actually been studied for.

MK-7 and Cardiovascular Endpoints

The population-level case for K2 and cardiovascular health rests heavily on the Rotterdam Study, which followed 4,807 Dutch adults over 55 for an average of 7–10 years. People in the highest tertile of dietary menaquinone (K2) intake had a roughly 40% lower risk of coronary heart disease and meaningfully less aortic calcification than those in the lowest tertile — and notably, dietary vitamin K1 showed no such association. The follow-up Prospect-EPIC cohort of over 16,000 women found each additional 10 mcg/day of K2 intake was tied to a 9% lower coronary heart disease risk, reinforcing the finding in a second population.

Observational data is one thing; intervention trials are another, and this is where MK-7 specifically — not MK-4 — has the clinical trial evidence. In a three-year, double-blind, placebo-controlled trial of 244 healthy postmenopausal women, 180 mcg/day of MK-7 significantly improved arterial stiffness compared to placebo, with the largest benefit in women who started with the stiffest arteries. The same trial found MK-7 cut circulating inactive matrix Gla-protein (dp-ucMGP, a marker of poor vitamin K status) by 50% relative to placebo. This is the trial I referenced in my own letter to the editor in JAMA Cardiology — I have a disclosed past relationship with NattoPharma, the company behind the MenaQ7 MK-7 ingredient used in that research, which is exactly why I’ve read this literature as closely as I have.

I go much deeper into this cardiovascular evidence base — including the 2025 VitaK-CAC trial, which found two years of MenaQ7 MK-7 slowed coronary artery calcification progression by 22% in patients with existing mild-to-moderate coronary artery disease — in my dedicated post on preventing atherosclerosis with vitamin K2. For a broader look at K2’s role in overall cardiovascular wellness beyond calcification specifically, see improving heart health with vitamin K2.

MK-4 and Bone Endpoints

MK-4’s strongest evidence base is different — and it’s pharmacological, not nutritional. As menatetrenone, MK-4 is an approved osteoporosis drug in Japan, marketed as Glakay, where it’s used at 45 mg/day (15 mg three times daily) to stimulate osteoblast activity and inhibit bone resorption. At that dose, MK-4 appears to work partly through mechanisms beyond simple vitamin K cofactor activity — including direct gene regulation effects on bone cells — which is part of why the two forms aren’t considered interchangeable at their respective effective doses.

MK-7 also has bone data of its own: the same Maastricht research group that ran the arterial stiffness trial found that three years of low-dose MK-7 (180 mcg/day) helped slow bone loss in healthy postmenopausal women, with comparable benefit to what’s been shown for MK-4 at pharmacological doses — but at a fraction of the dose and without prescription oversight.

The short version: MK-7’s trial evidence spans both bone and cardiovascular endpoints at a nutritional, once-daily dose. MK-4’s strongest evidence is for bone specifically, at a pharmaceutical dose that isn’t something you’re replicating with an over-the-counter capsule.

Bone health from K2 isn’t just an adult concern, either — children show the largest degree of K2 insufficiency of any age group by osteocalcin markers. I cover the pediatric dosing and evidence, including the 45 mcg/day MenaQ7 dose used in clinical trials of children, in 5 reasons kids need a vitamin K2 supplement.

Why MK-4’s Japanese Dosing Doesn’t Translate to a Daily US Supplement

I bring this up because it’s one of the more common points of confusion I see in client questions and in competitor content: people read that “45 mg of MK-4 treats osteoporosis in Japan” and assume that’s a supplement recommendation. It isn’t, for a few concrete reasons:

• It’s a prescription drug dose, not a nutritional one. Glakay is dispensed and monitored by a physician in Japan specifically for postmenopausal osteoporosis — it’s a pharmacological intervention, not a wellness routine.
• The dose is roughly 1,000 times higher than typical MK-7 supplementation. 45 mg (45,000 mcg) of MK-4 versus 90–200 mcg of MK-7 for comparable outcomes reflects MK-4’s poor bioavailability and short half-life, not a “stronger” nutrient.
• It has real contraindications. Menatetrenone at this dose is specifically contraindicated with warfarin and other vitamin K antagonists, and manufacturers explicitly warn against use in pregnancy and breastfeeding at this level.
• Off-the-shelf US MK-4 products don’t replicate this protocol. Most over-the-counter MK-4 supplements are dosed in the 1–5 mg range — well below the therapeutic Japanese dose, but still far above what MK-7 needs to achieve comparable serum activity, without the RCT support behind that specific dose.

If you have diagnosed osteoporosis and want to explore high-dose MK-4 therapy, that’s a conversation to have with your prescriber, ideally alongside DEXA monitoring and a full look at your calcium, vitamin D, and anticoagulant status — not a decision to make from a bottle on a shelf.

Reading a Supplement Label — What to Check For

If you’ve decided MK-7 is the right fit for your daily routine (which, for most people, it is), here’s what I actually look for on a label before I’ll consider a product:

• A branded, clinically studied MK-7 ingredient. Look for MenaQ7® or VitaMK7® by name. These are the trans-isomer forms used in the trials referenced above — not all synthetic or fermented MK-7 is produced or purified the same way, and the cis-isomer form found in some cheaper products is not biologically active.
• All-trans, not cis, configuration. A quality label will either state “all-trans MK-7” directly or reference a branded ingredient known to guarantee it.
• Dose in the 90–200 mcg range for general wellness use — this is the range used across the bone and cardiovascular trials, not an arbitrary marketing number.
• Third-party testing and GMP certification on the label or the brand’s website, confirming potency and purity.
• Paired with vitamin D3, if that’s your goal. D3 and K2 work as a team — D3 increases calcium absorption, and K2 directs where that calcium goes. A combined product isn’t required, but it simplifies routines for a lot of clients.
• A fat-containing delivery format or timing note. K2 is fat-soluble; taking it with a meal that contains some fat improves absorption regardless of which product you choose.

I personally take a liquid D3/K2 drop formula for exactly the label reasons above — a clinically dosed MenaQ7 MK-7 amount, minimal additives, and no extra pill to remember. I’ve taken vitamin K2 in some form for more than 10 years now, and MK-7 has been the constant throughout — it’s the form behind every recommendation I make for bone, heart, and gut health, including the colon health benefits I’ve written about separately. If you want to see the specific products I currently recommend and why, I keep an updated, fully sourced list in my best vitamin K2 supplement brands guide, including several available directly through my Fullscript dispensary.

Frequently Asked Questions

Is MK-7 better than MK-4?

For daily, nutritional-dose supplementation, yes — MK-7 has better bioavailability, a much longer half-life, and clinical trial support for both bone and cardiovascular endpoints at a practical once-daily microgram dose. MK-4 isn’t “worse,” but its strongest evidence is at a pharmaceutical dose (45 mg/day) used therapeutically for osteoporosis in Japan, which isn’t what most over-the-counter MK-4 products are dosed to deliver.

Do I need both forms?

Not for general wellness. Some combination products include both, and there’s no harm in that, but MK-7 will do the majority of the work for long-term bone and cardiovascular support because of its superior half-life. If you’re managing a diagnosed condition like osteoporosis, that’s a conversation for your provider — not something to solve by taking more forms at once.

Which form is in natto?

Natto — fermented soybeans, a traditional Japanese food — is the richest known dietary source of MK-7, produced by the bacteria Bacillus subtilis during fermentation. It’s part of why Japanese researchers were early to study K2’s role in bone health, even though the pharmaceutical osteoporosis treatment developed there (menatetrenone) is actually the MK-4 form, produced synthetically rather than from natto.

📚 More From The Healthy RD on Vitamin K2:

• Can You Prevent Atherosclerosis with Vitamin K2?
• Improve Your Heart Health with Vitamin K2
• 5 Reasons Kids Need a Vitamin K2 Supplement
• Do You Need K2 Vitamins for Colon Health?
• Vitamin K2 Deficiency: A Global Health Problem
• The Best Vitamin K2 Supplement Brands and Their Benefits

This article is for educational purposes and isn’t a substitute for individualized medical advice. Vitamin K2 interacts with warfarin and other anticoagulant medications — talk with your healthcare provider before starting any form of K2 supplementation, especially at higher doses. I have a disclosed past professional relationship with NattoPharma; product recommendations reflect my independent clinical assessment of the label criteria described above.