Introduction
Vitamin K2 MK-7 is sold by the microgram, and most dosing pages answer with a number and give no more information. Shoppers see 45, 90, 100, 180, and 360 micrograms on competing labels with no way to judge between them. Those numbers are not arbitrary, and they are not clinical recommendations either. Each one traces to a trial that measured a specific marker in certain people. This article explains where the trial doses came from and what the researchers measured. It also covers the form question, the food sources, and the interaction that matters most. You will finish this article able to read any MK-7 label and know what its number means.
What Is Vitamin K2 MK-7? A Closer Look
Vitamin K2 MK-7 is one member of a family of compounds called menaquinones. Every menaquinone shares the same ring structure and differs only in the length of its side chain. The number in the name counts the repeating units in that chain, so MK-7 carries seven of them. Bacteria make the long-chain forms, which is why MK-7 reaches the food supply through fermentation rather than through plants. Leafy greens supply phylloquinone instead, which is vitamin K1 and a different molecule with a different distribution in the body.
That side chain is not a chemical footnote, and it is the reason dose numbers differ so much between products. Absorption itself was similar for the two forms in healthy volunteers, with both peaking in serum four hours after intake (Schurgers et al., 2007). What differed was clearance since MK-7 persisted far longer in those volunteers and held their serum levels steadier. Repeated daily intake left MK-7 circulating at seven to eight times the concentration reached by vitamin K1 in them. A compound that lingers requires less of itself each day to hold a steady level.
One further detail separates a good MK-7 raw material from a poor one. MK-7 exists as geometric isomers, and only the all-trans form carries biological activity. Trans and cis MK-7 were compared for carboxylating activity in a cell-free system, and the trans form performed better (Cirilli et al., 2022). Fermentation and chemical synthesis do not yield the same mixture of those isomers. I will return to what that means for a supplement label in the forms section below.
What vitamin K does with that activity is switch on a specific set of proteins. Bone produces osteocalcin, while cartilage and the vessel wall produce matrix Gla protein (Schurgers et al., 2007). Production of both proteins goes ahead whether or not vitamin K is available, and both remain inert until carboxylation occurs. Carboxylation is therefore the step that separates a protein being present from a protein being useful. Where the body routes calcium once those proteins are working is a further question, and an article about IP6 is where I answer it.
Vitamin K2 MK-7 Dosage: What the Dose-Response Trials Measured
Every vitamin K2 MK-7 dosage number in circulation came from a trial, and those trials share one limitation. Almost all of them measured a blood marker of vitamin K status rather than a health outcome. The two markers are uncarboxylated osteocalcin and desphospho-uncarboxylated matrix Gla protein, and both fall when vitamin K intake rises. A marker moving is a real finding, and it does not amount to a person feeling or functioning differently. I am going to report the marker trials as marker trials.
The closest thing to a true dose-finding study randomized 42 healthy Dutch men and women aged 18 to 45. They were assigned to placebo or to MK-7 at 10, 20, 45, 90, 180, or 360 micrograms daily (Theuwissen et al., 2012). Seven arms of six people each is too small to compare every dose against every other dose. Its authors therefore collapsed the arms into three groups to gain statistical power, which is a limit worth stating plainly. Doses in the order of the European Union reference intake raised carboxylation of circulating osteocalcin and matrix Gla protein in those healthy adults.
A second trial tested the two amounts most often sold today. Sixty participants aged 40 to 65 took 180 micrograms of MK-7, 360 micrograms, or placebo for 12 weeks. Desphospho-uncarboxylated matrix Gla protein declined 31 percent and 46 percent across those two groups (Dalmeijer et al., 2012). The ratio of uncarboxylated to carboxylated osteocalcin declined 60 percent and 74 percent in the same participants. Other cardiovascular risk factors did not differ between the treatment arms in those participants.
Two trials went past markers to a physical measurement, and the first of them ran three years. Its 244 healthy postmenopausal women received either 180 micrograms of MK-7 each day or a placebo. Bone mineral density declined more slowly in the MK-7 arm at two of three measured sites (Knapen et al., 2013). Those sites were the femoral neck and the lumbar spine, but the total hip showed no difference in those women. Its authors cautioned that carrying the result across to children and to men would require further investigation. Postmenopausal women are the population behind most of this literature, which is one reason I wrote about brain health for women over 50.
The second study ran for two years and enrolled a population that was unhealthy. A randomized trial assigned 180 patients with symptomatic coronary artery disease to 360 micrograms of MK-7 daily or to placebo (Vossen et al., 2026). Coronary artery calcification scores rose in both groups of those patients across the two years. The rise was smaller in the MK-7 group, and the difference between the groups reached statistical significance. Its authors concluded that MK-7 may slow calcification in noncalcified plaques in patients with symptomatic coronary artery disease. They also wrote that the clinical significance of the finding remains to be determined.
One 2026 trial tested MK-7 against something a healthy person can actually feel, and it found nothing. Healthy young adults aged 18 to 40 and healthy older adults aged 65 and over took 240 micrograms of MK-7 or placebo for 12 weeks. Muscle strength, physical function, muscle soreness, and inflammatory response after resistance exercise did not differ between the groups (Lithgow et al., 2026). Circulating MK-7 rose in those adults, so the compound was absorbed and the outcomes still did not move. Reporting a null result that runs against my own category is the same discipline I apply in best supplements for memory loss.
MK-7 vs MK-4: Why the Form Changes the Dose
MK-7 vs MK-4 is the comparison that decides whether a dose number means anything at all. Both compounds are menaquinones, and both appear on supplement labels under the name vitamin K2. MK-4 carries four units in its side chain instead of seven, and that difference changes what happens after the capsule is swallowed. A microgram figure on an MK-4 label and the same figure on an MK-7 label describe two different exposures. The bioavailability work is where the two forms separate most sharply.
Healthy Japanese women received one 420 microgram dose of either MK-4 or MK-7 alongside a standardized breakfast. Serum MK-7 rose, peaked six hours later, and was still measurable in those women two days afterward. Serum MK-4 never appeared at all, in any subject, at any sampling point (Sato et al., 2012). A week of 60 micrograms of MK-4 daily also left serum MK-4 unchanged in them. The identical week of 60 micrograms of MK-7 raised serum MK-7 significantly in every woman studied.
Those authors drew a narrow conclusion, and the narrowness is exactly the point. MK-4 present in food does not contribute to vitamin K status as measured by serum vitamin K levels. That trial tested nutritional amounts in healthy Japanese women over a single week of repeated dosing. It says nothing about the far larger pharmacological amounts of MK-4 studied in other research settings. Anyone comparing the two forms should compare them at the amounts that were actually tested.
Form also changes what the compound does once it is absorbed. Osteocalcin carboxylation ran more complete on MK-7 than on vitamin K1 in the healthy volunteers who took both (Schurgers et al., 2007). That is a marker finding rather than a bone finding, and I will not inflate it into one. It does explain why the dose-response literature was built on MK-7 rather than on the other menaquinones. When you see 100 micrograms on a panel, the form printed beside the number decides what the number buys.
Vitamin K2 MK-7 Foods, Powder, and What a Label Can Hide
Vitamin K2 MK-7 foods are few, and a single dish dominates the list. A three-ounce portion of natto, the traditional Japanese dish of fermented soybeans, carries 850 micrograms of MK-7 (Office of Dietary Supplements, n.d.). Bacterial fermentation is what puts it there, so unfermented soy foods do not carry it. Cheese and curd are the most important long-chain menaquinone sources in the Western diet (Vermeer et al., 2018). Hard cheeses are generally richer in menaquinones than soft cheeses are. Menaquinone content varied substantially by cheese type, ripening time, fat content, and the region of production.
Japanese populations eat enough natto to have been studied as a natural experiment, with one large caveat. A meta-analysis pooled six observational and quasi-experimental studies covering 2,327 people in Japan (Wen et al., 2025). Its authors rated certainty of evidence as moderate for serum MK-7 and low to very low for the osteocalcin and bone outcomes. Habitual natto intake was associated with higher serum MK-7, higher carboxylated osteocalcin, and lower uncarboxylated osteocalcin in those Japanese adults. Bone mineral density was modestly greater across sites in them, and the authors cautioned against generalizing beyond Japanese populations.
Food can carry MK-7 at amounts well below a capsule and still move the markers. Healthy men and postmenopausal women with a mean age of 56 drank a fortified yogurt drink twice daily for 12 weeks. Each drink supplied 28 micrograms of MK-7, and circulating MK-7 rose from 0.28 to 1.94 nanograms per milliliter in them (Knapen et al., 2015). Both uncarboxylated osteocalcin and desphospho-uncarboxylated matrix Gla protein dropped significantly in those adults. Markers of inflammation, endothelial function, and lipid metabolism did not change in them. The drink also carried omega-3 fats, vitamin D, vitamin C, calcium, and magnesium, so no result there belonged to MK-7 alone.
Now the part of this subject that should trouble anyone selling MK-7, me included. A laboratory analysis identified and quantified cis and trans isomers of MK-7 in commercial dietary supplement products. All-trans content came in below the declared content in the majority of the products tested (Szterk et al., 2018). Measured all-trans MK-7 ranged from 5.5 to 49 micrograms per pill across that sample. In one product the vitamin was not found at all, regardless of the claim printed on its label.
Cis and trans isomer content exceeded the all-trans content by up to 3.7 times in some of those supplements. A careful dose argument is worthless if the number on the panel is not the number in the capsule. What a buyer can do about it is short and unglamorous. Ask the manufacturer for a certificate of analysis reporting all-trans MK-7 by assay rather than the amount added during blending. Naming the exact material and reporting what was measured on that material is the rule behind every ingredient in Daily Brain Care.
Vitamin K2 MK-7 Side Effects and the Anticoagulant Question
Vitamin K2 MK-7 side effects are dominated by one interaction, and its threshold is lower than most buyers expect. Eighteen healthy men and women were anticoagulated with acenocoumarol for four weeks, and 15 of them reached a target international normalized ratio of 2.0. They then took MK-7 at 10, 20, and 45 micrograms daily while continuing the drug (Theuwissen et al., 2013). A daily intake of 45 micrograms lowered group mean INR and uncarboxylated factor II by about 40 percent in those volunteers. Two hematologists independently judged that 10 and 20 micrograms caused clinically relevant lowering of INR in at least 40 and 60 percent of them.
Those authors concluded that MK-7 supplements need to be avoided by patients receiving vitamin K antagonist therapy. An earlier pharmacokinetic paper arrived at the same place from a different direction. Its authors warned hematologists about any preparation delivering 50 micrograms or more of MK-7 each day. Interference with oral anticoagulant treatment at that level can be clinically relevant (Schurgers et al., 2007). The NIH Office of Dietary Supplements frames the issue as consistency rather than as quantity. Anyone on warfarin or a similar anticoagulant needs vitamin K intake that stays steady from day to day. Either an increase or a decrease in that intake can shift how the drug performs (Office of Dietary Supplements, n.d.).
My own D3+K2 tablet contains 100 micrograms of MK-7, more than double the 45 micrograms that moved INR in that study. A person taking warfarin, or any other vitamin K antagonist, should raise it with the prescribing clinician first. The same applies to every MK-7 product on the market, at every amount used in that dose-response work. I would rather put this in my own article than leave a customer to discover it somewhere else.
Outside the anticoagulant question, the published record on MK-7 has been reviewed formally. A United States Pharmacopeial Convention review examined the chemistry, dietary sources, intake levels, and pharmacokinetics of menaquinone-7. The same review covered the nonclinical toxicity data and the reported adverse events (Marles et al., 2017). Its authors concluded that menaquinone-7 ingested as a dietary supplement is not associated with any serious risk to health or with other public health concerns. That review covers the ingredient as a class and speaks to no particular product, manufacturer, or raw material. The Food and Nutrition Board set no Tolerable Upper Intake Level for vitamin K, citing low potential for toxicity (Office of Dietary Supplements, n.d.). However, absence of a limit is not a license to take any amount.
Two further points belong in an honest safety section. Thrombin generation did not change in the 42 healthy adults given MK-7 at 10 to 360 micrograms daily (Theuwissen et al., 2012). Those adults were not taking an anticoagulant, which is the entire difference between that result and the one above. Pregnancy, nursing, and any prescription medication are all reasons to ask a qualified clinician before starting an MK-7 product.
How Much Vitamin K2 Per Day Do I Take, and Why
How much vitamin K2 per day you need depends on where your own markers already sit. Vitamin K status markers were measured in 896 samples from healthy volunteers across a wide age range. Children showed uncarboxylated osteocalcin between 3.4 and 96.9 nanograms per milliliter, while other age groups ran between 1.5 and 5.0 (Theuwissen et al., 2014). From the age of 40 onward, desphospho-uncarboxylated matrix Gla protein rose gradually in those volunteers. Its authors identified children and adults above 40 as the groups with the largest tissue-specific shortfall.
That rise from age 40 is a pattern rather than a prescription. A single measurement of a status marker does not tell an individual what will happen. Age-related change in the markers we can measure is the subject I discuss in an article on healthy aging. What the finding does tell me is that a 25-year-old and a 60-year-old are not asking the same question here. Selling both of them the same number is easier than saying so aloud.
The D3+K2 tablet I formulate carries 100 micrograms of MK-7 from natto in one chewable serving. That amount is higher than the 45 micrograms that altered INR in anticoagulated volunteers and below the 180 micrograms of the three-year trial. I chose it as a maintenance amount rather than as a trial-matching amount, so I will not borrow three-year results for my label. Vegan vitamin D3 from lichen is in the same tablet, and sunflower lecithin serves as its phospholipid carrier. That lecithin also forms the liposome the two actives are sealed inside, built as a dry powder by a patent-pending process. What human trials of liposomal delivery have and have not measured is set out in liposomal curcumin. I have not tested that tablet against a conventional one, so I claim nothing for it here. Naming both the form and the source of a nutrient is the least a label owes the person reading it.
One recent finding argues against the pairing I sell, and it belongs here rather than buried. A post-hoc analysis was conducted on a randomized vitamin D trial that gave 2,800 IU daily for eight weeks to 200 participants. Baseline vitamin K status did not modify the effect of vitamin D on bone turnover or cardiovascular markers in them (Theiler-Schwetz et al., 2026). Its authors noted that the finding is in line with current guidelines, which do not routinely recommend vitamin K and D co-treatment. I sell the two nutrients together, and I am telling you what the most recent analysis of that question reported. The case for pairing vitamin D with vitamin K rests mainly on mechanism, which I set out in vitamin D3 and K2.
What I do myself has never depended on a tablet, and I will not pretend otherwise now. I have eaten a whole-food, plant-based diet since 1999, which removes cheese as a menaquinone source for me. Natto is the food answer, but I do not eat it. Drug-free high-intensity bodybuilding for decades has shaped how I read a dose claim, and I detail that history on my About page. Nothing in this article rearranges the order, since food and training sit ahead of any microgram figure.
Readers ask whether MK-7 can simply be added to whatever is already in the cabinet. My answer is that this nutrient carries a real drug interaction and a real form problem, so it earns a decision of its own. Daily Brain Care is formulated on a different principle, which is a fixed whole-food matrix taken at the same serving every single day. Dr Lewis Nutrition® was built on naming what is in a product and reporting what has been measured on that material. A microgram figure you can defend is worth more than one that looks impressive on a panel.
Conclusion
Vitamin K2 MK-7 dosing stops being mysterious once the origin of each number is clear. The common label amounts trace to trials that measured carboxylation markers in healthy adults, not on outcomes those adults could feel. The form beside the number matters, the all-trans content matters more, and the anticoagulant threshold is low. Knowing all three, you can choose an amount deliberately instead of by price. If you want MK-7 from natto at an amount I can defend, our D3+K2 is where I would start.
Frequently Asked Questions
What is vitamin K2 MK-7?
MK-7 is menaquinone-7, a long-chain member of the vitamin K2 family produced by bacterial fermentation. Its side chain carries seven repeating units, which gives it a much longer half-life than vitamin K1 has. Natto, a traditional Japanese food made from fermented soybeans, is the richest food source. Only the all-trans isomer of MK-7 carries biological activity.
What does MK-7 do?
Vitamin K acts as a cofactor for carboxylation of several proteins, among them bone osteocalcin and vascular matrix Gla protein. Those proteins are produced without vitamin K and remain inactive until they are carboxylated. MK-7 supplies that cofactor and stays in circulation far longer than vitamin K1 does. Carboxylation is the step that turns a protein from present into functional.
What is MK-7 good for?
Most MK-7 research has measured markers of vitamin K status in healthy adults. A three-year trial measured bone mineral density in healthy postmenopausal women, and a two-year trial measured coronary calcification in patients with symptomatic coronary artery disease. A 2026 trial found no effect on strength, function, soreness, or inflammation after resistance exercise in healthy adults. I report the null results alongside the rest.
How much vitamin K2 per day should you take?
The Adequate Intake for vitamin K is 120 micrograms daily in adult men and 90 micrograms in adult women. No Tolerable Upper Intake Level exists for the vitamin. Trials have used MK-7 at 10 to 360 micrograms daily, with 180 micrograms the most common amount in the longer studies. My own tablet holds 100 micrograms as a maintenance amount. Settling on your own number is a conversation to have with your own clinician.
Is vitamin K2 MK-7 bad for you?
Warfarin and the other vitamin K antagonists are the first consideration, so consult the prescribing clinician before taking any MK-7. A dose-response trial reported clinically relevant lowering of INR at 10 and 20 micrograms daily in anticoagulated healthy volunteers. A United States Pharmacopeial Convention review concluded that menaquinone-7 as a dietary supplement is not associated with any serious risk to health. Pregnancy, nursing, and prescription medicine each call for clinical input first.
References
Cirilli, I., Orlando, P., Silvestri, S., Marcheggiani, F., Dludla, P. V., Kaesler, N., & Tiano, L. (2022). Carboxylative efficacy of trans and cis MK7 and comparison with other vitamin K isomers. BioFactors, 48(5), 1129–1136. https://doi.org/10.1002/biof.1844
Dalmeijer, G. W., van der Schouw, Y. T., Magdeleyns, E., Ahmed, N., Vermeer, C., & Beulens, J. W. (2012). The effect of menaquinone-7 supplementation on circulating species of matrix Gla protein. Atherosclerosis, 225(2), 397–402. https://doi.org/10.1016/j.atherosclerosis.2012.09.019
Knapen, M. H. J., Braam, L. A. J. L. M., Teunissen, K. J., Zwijsen, R. M., Theuwissen, E., & Vermeer, C. (2015). Yogurt drink fortified with menaquinone-7 improves vitamin K status in a healthy population. Journal of Nutritional Science, 4, e35. https://doi.org/10.1017/jns.2015.25
Knapen, M. H. J., Drummen, N. E., Smit, E., Vermeer, C., & Theuwissen, E. (2013). Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporosis International, 24(9), 2499–2507. https://doi.org/10.1007/s00198-013-2325-6
Lithgow, H., Johnston, L., Ho, F., Dunning, E., Nakada, S., Celis-Morales, C., Hunter, A. M., Lees, J. S., Mark, P. B., Quinn, T. J., & Gray, S. R. (2026). The effects of vitamin K2 on recovery from muscle-damaging resistance exercise in young and older adults: The TAKEOVER randomized controlled trial. Medicine and Science in Sports and Exercise, 58(4), 683–694. https://doi.org/10.1249/MSS.0000000000003901
Marles, R. J., Roe, A. L., & Oketch-Rabah, H. A. (2017). US Pharmacopeial Convention safety evaluation of menaquinone-7, a form of vitamin K. Nutrition Reviews, 75(7), 553–578. https://doi.org/10.1093/nutrit/nux022
Office of Dietary Supplements. (n.d.). Vitamin K: Fact sheet for health professionals. National Institutes of Health. Retrieved September 14, 2026, from https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/
Sato, T., Schurgers, L. J., & Uenishi, K. (2012). Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Nutrition Journal, 11, 93. https://doi.org/10.1186/1475-2891-11-93
Schurgers, L. J., Teunissen, K. J. F., Hamulyák, K., Knapen, M. H. J., Vik, H., & Vermeer, C. (2007). Vitamin K-containing dietary supplements: Comparison of synthetic vitamin K1 and natto-derived menaquinone-7. Blood, 109(8), 3279–3283. https://doi.org/10.1182/blood-2006-08-040709
Szterk, A., Zmysłowski, A., & Bus, K. (2018). Identification of cis/trans isomers of menaquinone-7 in food as exemplified by dietary supplements. Food Chemistry, 243, 403–409. https://doi.org/10.1016/j.foodchem.2017.10.001
Theiler-Schwetz, V., Riedmann, U., Zelzer, S., Meinitzer, A., Schmitt, L., Kraus, D. A., Trummer, C., Grübler, M. R., Keppel, M. H., Zittermann, A., Tomaschitz, A., März, W., Pludowski, P., & Pilz, S. (2026). Vitamin K status has no influence on the effect of vitamin D supplementation on bone turnover and cardiovascular markers: A randomized controlled trial. Frontiers in Nutrition, 13, 1857443. https://doi.org/10.3389/fnut.2026.1857443
Theuwissen, E., Cranenburg, E. C., Knapen, M. H., Magdeleyns, E. J., Teunissen, K. J., Schurgers, L. J., Smit, E., & Vermeer, C. (2012). Low-dose menaquinone-7 supplementation improved extra-hepatic vitamin K status, but had no effect on thrombin generation in healthy subjects. British Journal of Nutrition, 108(9), 1652–1657. https://doi.org/10.1017/S0007114511007185
Theuwissen, E., Magdeleyns, E. J., Braam, L. A., Teunissen, K. J., Knapen, M. H., Binnekamp, I. A., van Summeren, M. J., & Vermeer, C. (2014). Vitamin K status in healthy volunteers. Food & Function, 5(2), 229–234. https://doi.org/10.1039/c3fo60464k
Theuwissen, E., Teunissen, K. J., Spronk, H. M., Hamulyák, K., Ten Cate, H., Shearer, M. J., Vermeer, C., & Schurgers, L. J. (2013). Effect of low-dose supplements of menaquinone-7 (vitamin K2) on the stability of oral anticoagulant treatment: Dose-response relationship in healthy volunteers. Journal of Thrombosis and Haemostasis, 11(6), 1085–1092. https://doi.org/10.1111/jth.12203
Vermeer, C., Raes, J., van ’t Hoofd, C., Knapen, M. H. J., & Xanthoulea, S. (2018). Menaquinone content of cheese. Nutrients, 10(4), 446. https://doi.org/10.3390/nu10040446
Vossen, L. M., de Leeuw, P. W., Schurgers, L. J., Heuts, S., Adriaans, B. P., de Haan, C., van Varik, B. J., & Kroon, A. A. (2026). Two years of menaquinone-7 supplementation and coronary artery calcification: A randomized clinical trial. JAMA Cardiology, 11(8), 719–726. https://doi.org/10.1001/jamacardio.2026.1279
Wen, Z., Zhen, M., Wang, J., Agudamu, A., & Zhang, Y. (2025). Habitual natto intake elevates serum MK-7 levels, enhances osteocalcin carboxylation, and supports bone density: A meta-analysis of Japanese evidence. Frontiers in Nutrition, 12, 1713726. https://doi.org/10.3389/fnut.2025.1713726
