Most vitamin K2 supplements list one of two forms on the label: MK-7 or MK-4. The names look almost the same. They do not work the same.
The short answer
MK-7 stays in your blood for days. MK-4, at the doses found in most supplements, barely shows up in your blood at all. That is why Mega Restore uses MK-7.
What happened when researchers compared them
In a 2012 study, healthy women took the same dose of MK-7 or MK-4, 420 mcg, one time.
- MK-7 showed up in the blood, peaked about six hours later, and could still be measured two days later.
- MK-4 could not be measured in anyone's blood at any time.
Next, the women took a smaller dose, 60 mcg, every day for a week. MK-7 levels went up in every person. MK-4 levels did not go up at all.
Why lasting longer matters
Vitamin K2 switches on the proteins that move calcium into bone and keep it out of artery walls. To do that job, it has to be in your blood.
Because MK-7 lasts for days, it builds up when you take it daily. An earlier study found that daily MK-7 built up to levels seven to eight times higher than vitamin K1. So one capsule a day keeps a steady supply.
What to look for on a label
- The words "MK-7" or "menaquinone-7."
- The dose in mcg. The studies that measured K2 at work used 180 to 360 mcg of MK-7 a day. Mega Restore has 300 mcg. Our post How much vitamin K2 should you take with 5,000 IU of vitamin D3? explains why.
If you take a blood thinner
Because MK-7 lasts so long, it matters for people on warfarin (Coumadin). Vitamin K works against warfarin, and in one study as little as 10 mcg a day of MK-7 changed how well it worked in some people. If you take warfarin, talk to the clinician who manages it before starting any vitamin K.
Newer blood thinners like Eliquis (apixaban), Xarelto (rivaroxaban), Pradaxa (dabigatran) and Savaysa (edoxaban) work in a different way. Vitamin K does not change how they work. Still, if you take any blood thinner, check with your prescriber before adding a supplement.
Mega Restore is 200 mg ubiquinol, 5,000 IU vitamin D3 and 300 mcg vitamin K2 as MK-7 in one daily capsule. $89.99 for a 90-day supply, free U.S. shipping. See the full label and buy.
Sources
Article records and abstracts retrieved from PubMed.
- 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, et al. Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7. Blood. 2007;109(8):3279-83. doi:10.1182/blood-2006-08-040709
- Dalmeijer GW, et al. The effect of menaquinone-7 supplementation on circulating species of matrix Gla protein. Atherosclerosis. 2012;225(2):397-402. doi:10.1016/j.atherosclerosis.2012.09.019
- Theuwissen E, et al. Effect of low-dose supplements of menaquinone-7 (vitamin K2) on the stability of oral anticoagulant treatment. J Thromb Haemost. 2013;11(6):1085-92. doi:10.1111/jth.12203
- Steffel J, et al. 2021 European Heart Rhythm Association practical guide on the use of non-vitamin K antagonist oral anticoagulants in patients with atrial fibrillation. Europace. 2021;23(10):1612-1676. doi:10.1093/europace/euab065
*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.
