MK-4 vs. MK-7: both are forms of vitamin K2, but they behave very differently in the body. MK-7 stays in the blood for about three days, so small microgram amounts taken once a day build up steadily. MK-4 clears within a few hours, so studies use it at much larger milligram doses, often split through the day. That difference is why most daily K2 supplements, including ours, use MK-7.
Vitamin K2 has moved from an obscure nutrient to a regular part of bone-health routines, usually paired with vitamin D3. But labels list it in different ways: "menaquinone," "MK-4," "MK-7," sometimes just "K2." Here is what those names mean and how to read them.
Key takeaways
- Vitamin K1 comes mainly from leafy greens; vitamin K2 is a family of compounds called menaquinones.
- MK-7 stays in the blood for about three days, while MK-4 clears within a few hours.
- MK-7 is used in microgram amounts; MK-4 is studied in milligram amounts.
- Anyone who takes a blood thinner should talk with a healthcare provider before taking any form of vitamin K.
What is vitamin K2?
Vitamin K is not one compound but a small family. Vitamin K1 comes mainly from leafy greens; vitamin K2 is a family of compounds called menaquinones. Each menaquinone is named by the length of its side chain: MK-4, MK-7, MK-8, MK-9 and so on. The number tells you how many units long that chain is, and the length changes how the molecule is absorbed and how long it lasts in the body.
All forms of vitamin K help the body use proteins involved in normal blood clotting and in bone. Vitamin K2 supports bone health and promotes healthy arteries by helping direct calcium where the body needs it.* That is why it is so often paired with vitamin D3, which promotes calcium absorption.*
MK-4 vs. MK-7: the key differences
| Feature | MK-4 | MK-7 |
|---|---|---|
| Main food sources | Animal foods: egg yolk, butter, meat, some cheeses | Fermented foods, especially natto (fermented soybeans) |
| Time in the blood | A few hours | About three days |
| Amounts used in studies | Milligrams, often split through the day | Micrograms, once a day |
| Detectable in blood at food-level doses | Not in one comparison study | Yes |
| Common in daily supplements | Less common | Most common |
How long each form lasts
MK-7 stays in the blood for about three days, while MK-4 clears within a few hours. Researchers describe the half-life of MK-7 as roughly 72 hours, compared with about 1 to 2 hours for MK-4. A longer half-life means a steady once-a-day amount can build up to a stable level, which is convenient for a daily routine.
The dose difference
MK-7 is used in microgram amounts; MK-4 is studied in milligram amounts. A milligram is a thousand micrograms, so the gap is large. In a 2012 comparison study, a single food-level dose of MK-7 raised blood levels for at least 48 hours, while the same small dose of MK-4 was not detected in the blood at all. MK-4 research, much of it from Japan, uses far higher amounts than any daily multinutrient formula provides.
Is MK-7 better than MK-4?
For a once-a-day supplement at microgram amounts, MK-7 has the practical advantage: it is well absorbed at those amounts and lasts long enough to keep levels steady. That does not make MK-4 "bad." It is the form your body makes and stores in some tissues, it is found naturally in common foods, and it has its own body of research at higher doses. The two forms are simply suited to different jobs.
The fair way to put it: if you want a simple daily K2 routine, MK-7 is the form designed for it. If a healthcare provider recommends MK-4 for a specific reason, follow their advice.
How to read vitamin K2 on a label
- Look for the form. "Vitamin K2 (as menaquinone-7)" or "MK-7" tells you which menaquinone you are getting. "Vitamin K" alone may be K1.
- Check the unit. MK-7 is listed in micrograms (mcg). If a label lists milligrams, it is probably MK-4.
- Note the pairing. Many K2 products include vitamin D3; count that vitamin D toward your daily total.
- Look for testing. Microgram amounts are small, which makes accurate dosing and third-party testing especially important.
For example, Vitamin K2/D3+ lists Vitamin K2 (MK-7) as menaquinone, 100 mcg, alongside 125 mcg (5,000 IU) of vitamin D3, in one capsule a day. That vitamin D amount is above the 100 mcg (4,000 IU) daily upper limit for adults, so check with your healthcare provider before use, especially if you take vitamin D from another product. Our article on why vitamin K2 and D3 work together explains the pairing, and how much vitamin D you need per day covers the numbers.
Food sources of vitamin K2
You can get some K2 from food. Natto is by far the richest source of MK-7, though its strong taste and sticky texture are not for everyone. Hard and soft cheeses provide longer-chain menaquinones, and egg yolks, butter, chicken and other animal foods provide MK-4. Gut bacteria also make some menaquinones, though how much the body uses is not clear.
A varied diet with leafy greens (for K1) and some of these foods supports overall vitamin K intake. A supplement is an option when your diet does not supply much K2.
Who should be careful with vitamin K2?
If you take a blood thinner, talk with a healthcare provider before taking any form of vitamin K. Vitamin K can change how warfarin and similar medications work, and steady, predictable intake matters. If you are pregnant, nursing or managing a medical condition, check with your provider first too.
Every batch of Vitamin K2/D3+ is third-party tested for purity and potency, and it is manufactured in USA with globally sourced materials in an NSF-certified, GMP-certified, FDA-registered facility. See Our Standards.
Frequently asked questions about MK-4 vs. MK-7
What is the difference between vitamin K1 and K2?
K1 (phylloquinone) comes mainly from leafy green vegetables. K2 (menaquinones) comes from fermented foods and animal foods and includes several forms, such as MK-4 and MK-7. They share core functions but differ in how they are absorbed and how long they last in the body.
Why do most supplements use MK-7?
MK-7 is well absorbed at microgram amounts and stays in the blood for about three days, so a once-a-day dose keeps levels steady. MK-4 clears within hours and is studied at much higher amounts.
Can I take MK-4 and MK-7 together?
Some products combine them. There is no strong evidence that combining them is necessary for a daily routine. If you are considering higher amounts of MK-4, talk with your healthcare provider.
Should vitamin K2 be taken with vitamin D3?
They are often paired because they work as a team on calcium: D3 promotes calcium absorption, and K2 helps guide calcium toward the bones.* Count the vitamin D from every product you take.
Is vitamin K2 safe with blood thinners?
Not without your provider's input. Vitamin K affects how warfarin and similar medicines work. Talk with your healthcare provider before starting any vitamin K supplement.
Related reading from our Wellness Hub
- Why Vitamin K2 and D3 Work Better Together: The Calcium Connection
- How to Keep Bones Strong
- How Much Vitamin D Do You Need Per Day? A Clear Guide
Sources
- NIH Office of Dietary Supplements: Vitamin K Fact Sheet for Health Professionals
- Sato T, et al. Comparison of menaquinone-4 and menaquinone-7 bioavailability. Nutrition Journal, 2012 (PMC)
- NIH Office of Dietary Supplements: Vitamin D Fact Sheet for Health Professionals
- Linus Pauling Institute, Oregon State University: Vitamin K
Individual results vary.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
