MK-4 vs MK-7: Which Vitamin K2 to Choose (Nutritionist Explains)

If you're choosing between two K2 supplements and don't understand which to pick — that's normal. The market has two forms (MK-4 and MK-7), and sellers often claim one is "better" than the other. The reality is more nuanced.

I'm Tatiana Zabalueva, a nutritionist. Over 10 years of practice — about 30,000 clients. In this article, I'll explain the difference in plain language and tell you why I chose MK-4 for our NAN D3+K2 formula.

Why You Need Vitamin K2 in the First Place

Vitamin K2 is the "navigator" for calcium in your body. Without it, calcium can deposit where it shouldn't — in artery walls, joints, kidneys. With K2, calcium goes where it should — into bones, teeth, and tissue.

If you take Vitamin D3 without K2, you risk raising blood calcium without directing it properly. That's why D3 and K2 work only as a pair.

MK-4 and MK-7 — What Are These Two Forms

Vitamin K2 isn't one substance — it's a group of forms called "menaquinones," numbered by side-chain length: MK-4, MK-5, MK-7, MK-9, and so on. Most supplements use either MK-4 or MK-7.

MK-4 (menaquinone-4)

• Found in: animal tissue — meat, liver, egg yolks, dairy
• How it absorbs: tissue (bones, vessels, brain) uses it directly, without conversion
• Speed: absorbs instantly — peaks in blood within 1–2 hours
• Half-life: short — 1–2 hours in blood
• Dose: 100–500 mcg daily — typical supplement range

MK-7 (menaquinone-7)

• Found in: fermented foods — Japanese natto, hard cheeses
• How it absorbs: circulates in blood; tissue must "process" it before using
• Speed: slower — peaks in 4–6 hours
• Half-life: long — 3 days in blood
• Dose: 45–180 mcg daily — usually less than MK-4

The Main Difference — Where It Works

Many supplement sellers say: "MK-7 is better because it stays in the blood longer." That's true, but it's not the whole story.

Longer in blood ≠ works better in tissue.

MK-4 leaves the blood quickly, but in that time it reaches tissue and is used immediately. MK-7 stays in blood longer, but tissue still needs to convert it or wait for it to arrive. Two different approaches:

• MK-7: "arrived and parked for 3 days" — stable but slow to work
• MK-4: "arrived and got to work" — fast, but requires daily intake

Comparison Table

Parameter	MK-4	MK-7
Source	Animal tissue	Fermented foods
Tissue uptake	Direct, no conversion	Through metabolism
Speed of action	Instant (1–2 hr)	Slower (4–6 hr)
Blood half-life	Short (hours)	Long (days)
Best for	Daily intake	Every-few-days dosing
Typical dose	100–500 mcg	45–180 mcg

Why I Chose MK-4 for NAN

"Most supplements use MK-7 — it's not worse. But MK-4 is the form of K2 that tissue (bone, vessels, brain) uses directly, without conversion. It absorbs instantly and goes straight to work.

MK-7 stays in the blood longer, but the body still has to process it before tissue can use it. I chose MK-4 because our formula is built for daily intake — every day you get a ready-to-work vitamin, not a delayed effect."

— Tatiana Zabalueva

The logic: if you take vitamin K2 every day (and our D3+K2 spray is built exactly for that), you don't need a long half-life. You're replenishing daily anyway. What you need is a form tissue can use immediately. That's MK-4.

MK-7 would make sense if the supplement were taken every 2–3 days — there, long half-life genuinely matters. But that's not what we made. We made a daily ritual.

How to Take MK-4 Properly

Vitamin K2 is fat-soluble. That means it needs fat to absorb. A few rules:

• Take with food that contains fat — butter, nuts, avocado, fish
• Don't take on an empty stomach — half just passes through
• If you use a sublingual spray (like our NAN D3+K2) — the formula already contains MCT oil, and the active is absorbed through mucous membrane directly, bypassing the stomach
• Timing isn't critical, but I usually recommend morning or with lunch

What to Choose

Take MK-4 if:

• You're willing to take supplements daily (recommended)
• You want speed of absorption and action
• You want the form that occurs naturally in animal tissue

Take MK-7 if:

• You want to dose every 2–3 days
• Constant blood presence matters to you
• You like sources from fermented soy (natto)

In most cases, for regular supplementation I recommend MK-4. Especially combined with D3 in a sublingual spray — that's the fastest and most complete absorption.

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See NAN D3+K2 spray with MK-4 →

This is educational content. Consult your healthcare provider before starting any supplement, especially if you take blood thinners (warfarin, heparin, etc.) — vitamin K affects their action.

References

1. Sato T et al., 2012, Nutr J — MK-4 vs MK-7 bioavailability. PMID: 23140417
2. Theuwissen E et al., 2012, Adv Nutr — Vitamin K in soft-tissue calcification. PMID: 22516724
3. Palacios C, Gonzalez L, 2014, J Steroid Biochem — Vitamin D deficiency: global public health problem. PMID: 24239505
4. Levis S et al., 2005, JCEM — Vitamin D deficiency in adult South Florida population. PMID: 15634725