Two labels say "vitamin K2," but one lists MK-7 and the other MK-4. They're both menaquinones, yet they're absorbed differently and have been studied at very different doses. Here's how to make sense of it.
Written by Vita Globe Editorial Team | Reviewed against NIH guidance and peer-reviewed research
Is MK-7 or MK-4 the better form of vitamin K2?
At everyday supplement doses, MK-7 has the stronger case. It's well absorbed, peaks in the blood about 6 hours after a dose and stays detectable for up to 48 hours, while nutritional doses of MK-4 weren't detectable in the blood at all[1]. MK-7 also has a much longer half-life than K1[2]. MK-4 has been studied mainly at a very high dose (45 mg a day) in Japanese trials[3][4].
Caveat: "Better" depends on the goal and dose. No trial has directly compared the two forms for long-term health outcomes.
Sources: Sato et al., 2012 · Schurgers et al., 2007 · NIH ODS · Cockayne et al., 2006 · Verified 2026-09-27
In this article
What are MK-7 and MK-4?
Both are menaquinones, the family we call vitamin K2. The number refers to the length of a side chain on the molecule[3].
- MK-4 has a short side chain. Your body makes it from vitamin K1, and it's found in animal foods like chicken, eggs and dairy[3].
- MK-7 has a longer side chain. It's made by bacteria and is abundant in natto, fermented soybeans[3].
Both help activate vitamin K-dependent proteins, the same basic job as K1. For the bigger K1 versus K2 picture, see vitamin K1 vs. K2.
How do MK-7 and MK-4 differ in absorption?
This is the biggest practical difference. In a study of healthy women, a single 420 mcg dose of MK-7 was well absorbed, reaching peak blood levels at about 6 hours and remaining detectable for up to 48 hours. The same dose of MK-4 wasn't detectable in anyone's blood at any time point. When taken daily at 60 mcg for a week, MK-7 raised blood levels significantly, while MK-4 did not[1].
A separate study found MK-7 has a much longer half-life than K1 and builds up to higher, steadier levels with daily dosing[2].
| MK-7 | MK-4 | |
|---|---|---|
| Source | Bacteria; natto | Made from K1 in the body; animal foods |
| Blood levels at nutritional doses | Rise and persist | Not detectable in the Sato study |
| Typical study dose | Micrograms (e.g., 180 mcg/day) | Milligrams (45 mg/day) |
What does the research on each form show?
MK-4. Most MK-4 research comes from Japan, where a 45 mg daily dose (roughly 45,000 mcg) has been used for osteoporosis[3]. A 2006 meta-analysis of randomized trials, mostly Japanese studies using this high dose, found MK-4 was linked to fewer fractures[4]. More recent studies have been mixed[3]. A three-year Dutch trial using high-dose MK-4 reported improved hip bone strength measures in postmenopausal women[5].
MK-7. MK-7 is studied at microgram doses much closer to dietary amounts. A three-year trial of 180 mcg MK-7 a day slowed bone density loss at the lower spine and femoral neck in postmenopausal women[6].
The honest summary
- At microgram doses, MK-7 is far better absorbed than MK-4.
- MK-4 evidence mostly comes from very high, drug-like doses.
- Neither form is proven to prevent disease in the general population.
Is one form safer than the other?
Both have good safety records. The NIH notes no adverse effects from vitamin K in food or supplements have been reported, and no upper limit has been set[3]. A U.S. Pharmacopeia review found MK-7 supplements aren't associated with any serious health risk[7].
The warfarin caveat applies to both, and it's especially relevant for MK-7. Because it lingers in the blood, MK-7 counteracted an oral anticoagulant at lower doses than K1 in one study[2]. See vitamin K2 and blood thinners.
How to read a vitamin K2 label
- Look for the form. Good labels specify MK-7 or MK-4 (sometimes as "menaquinone-7").
- Check the unit. MK-7 is listed in micrograms (mcg). A label listing milligrams of MK-4 is a much higher dose.
- Note the %DV. The Daily Value is based on vitamin K overall, not K2 specifically.
Our option
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Frequently asked questions
Is MK-7 better than MK-4?
For absorption at everyday doses, yes: MK-7 raised blood levels while nutritional doses of MK-4 did not[1]. MK-4 has been studied mostly at 45 mg a day[3].
Why is MK-4 dosed so much higher?
At nutritional doses, MK-4 didn't show up in the blood in one study[1]. The Japanese osteoporosis research used a high, drug-like dose of 45 mg a day[3].
Is MK-7 from natto?
Natto is the richest food source of MK-7[3], and natto-derived MK-7 is a supplement ingredient that has been studied directly[2].
Can I take MK-4 and MK-7 together?
Some products combine them. There's no evidence the combination is better than MK-7 alone, and it's worth checking total doses with your provider if you take medications.
Sources
- Sato T, Schurgers LJ, Uenishi K. Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Nutr J. 2012;11:93. doi:10.1186/1475-2891-11-93
- Schurgers LJ, Teunissen KJF, Hamulyák K, Knapen MHJ, Vik H, Vermeer C. Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7. Blood. 2007;109(8):3279-3283. doi:10.1182/blood-2006-08-040709
- Office of Dietary Supplements, National Institutes of Health. Vitamin K: Fact Sheet for Health Professionals. Updated March 29, 2021. ods.od.nih.gov
- Cockayne S, Adamson J, Lanham-New S, Shearer MJ, Gilbody S, Torgerson DJ. Vitamin K and the prevention of fractures: systematic review and meta-analysis of randomized controlled trials. Arch Intern Med. 2006;166(12):1256-1261. doi:10.1001/archinte.166.12.1256
- Knapen MHJ, Schurgers LJ, Vermeer C. Vitamin K2 supplementation improves hip bone geometry and bone strength indices in postmenopausal women. Osteoporos Int. 2007;18(7):963-972. doi:10.1007/s00198-007-0337-9
- Knapen MHJ, Drummen NE, Smit E, Vermeer C, Theuwissen E. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporos Int. 2013;24(9):2499-2507. doi:10.1007/s00198-013-2325-6
- Marles RJ, Roe AL, Oketch-Rabah HA. US Pharmacopeial Convention safety evaluation of menaquinone-7, a form of vitamin K. Nutr Rev. 2017;75(7):553-578. doi:10.1093/nutrit/nux022
About the Vita Globe Editorial Team
The Vita Globe Editorial Team researches and writes our wellness content, working from peer-reviewed research, systematic reviews and guidance from bodies such as the NIH and the FDA. We cite our sources inline and update articles when the evidence changes.
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. This article is for informational purposes only and is not a substitute for medical advice. Talk to your healthcare provider before starting any new supplement, particularly if you are pregnant, nursing, taking medication, or caring for a child.
