If you take 5,000 IU of vitamin D3, you have probably read that you should take vitamin K2 with it. Then comes the next question: how much? Many sites give one number, usually 100 mcg, as if it were settled. It is not.
The short answer
No study has found a best ratio of vitamin D3 to K2. What we do have are trials that measured how well different doses of K2 work. Those trials used 180 to 360 mcg of K2 as MK-7 a day. Mega Restore uses 300 mcg of MK-7 with 5,000 IU of D3.
Why D3 and K2 go together
Vitamin D helps your gut absorb calcium. It also tells your body to make more of the proteins that move calcium. One puts calcium into bone. Another, called MGP, keeps calcium out of artery walls. These proteins are made switched off. Vitamin K2 switches them on. So the more vitamin D you take, the more proteins there are for K2 to switch on.
Where the 100 mcg number comes from
The 100 mcg figure is a rule of thumb. It is a common, low-cost amount that fits easily in a small capsule. We could not find a trial that tested it as the right partner for 5,000 IU. That does not make it wrong. It just means it is a habit, not a finding.
What the studies measured
There is a blood test for the switched-off form of MGP. The lower it goes, the more of your MGP is switched on. Researchers use it to see whether a dose of K2 is doing its job.
- In healthy adults eating normal diets, 10 to 40 percent of these proteins stay switched off.
- In a 12-week trial of 60 adults aged 40 to 65, 180 mcg of MK-7 a day lowered switched-off MGP by 31 percent. 360 mcg lowered it by 46 percent. Placebo did nothing. More K2 switched on more MGP.
- In a three-year trial of 244 healthy women after menopause, 180 mcg of MK-7 a day cut switched-off MGP in half.
Why 300 mcg
300 mcg sits between the two doses in the 12-week trial, and it is three times the 100 mcg many D3 and K2 products use. We chose it because 5,000 IU is a higher dose of vitamin D, and a higher dose means more proteins waiting to be switched on. In a study of healthy men through a Nebraska winter, the body seemed to use 3,000 to 5,000 IU of vitamin D a day. That is the range we built the formula around.
MK-7 is also the form used in these trials. It lasts in your blood for days, so one capsule a day keeps a steady level.
What to check on your label
- The form. Look for "MK-7" or "menaquinone-7." "Vitamin K" alone, or K1, is not the same thing.
- The dose, in mcg. Compare it with the 180 to 360 mcg the trials used.
- Your total vitamin D. If you also take a multivitamin with D in it, add them up. Our post Is 5,000 IU of vitamin D too much? explains the limits.
If you take a blood thinner
If you take warfarin (Coumadin), do not start vitamin K2 on your own. 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. Talk to the clinician who manages it first.
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.
- 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
- Knapen MHJ, et al. Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women. Thromb Haemost. 2015;113(5):1135-44. doi:10.1160/TH14-08-0675
- Theuwissen E, et al. Low-dose menaquinone-7 supplementation improved extra-hepatic vitamin K status. Br J Nutr. 2012;108(9):1652-7. doi:10.1017/S0007114511007185
- Heaney RP, et al. Human serum 25-hydroxycholecalciferol response to extended oral dosing with cholecalciferol. Am J Clin Nutr. 2003;77(1):204-10. doi:10.1093/ajcn/77.1.204
- 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
- van Ballegooijen AJ, et al. The synergistic interplay between vitamins D and K for bone and cardiovascular health: a narrative review. Int J Endocrinol. 2017;2017:7454376. doi:10.1155/2017/7454376
*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.
