vitaminNot FDA-approvedOTC supplementMK-4 at 45 mg/day is a prescription osteoporosis drug in Japan, not a US supplement doseInteracts with warfarin
Vitamin K2Benefits, Dosage & Interactions
Also known as: mk-7, menaquinone
Vitamin K2, also known as menaquinone, is a fat-soluble vitamin that plays a crucial role in several physiological processes, primarily blood coagulation, bone metabolism, and cardiovascular health. Research on Vitamin K2 focuses on bone and joint health, menopause symptoms, and men's healthspan.
How much Vitamin K2 do people take?
180 mcg/day of MK-7 in the arterial-stiffness trial; 45 mg/day of MK-4 (menatetrenone) in the Japanese fracture trial. Route reported: Oral. Frequency reported: Once daily for MK-7; three times daily for MK-4 in that trial. These are amounts documented in the cited studies and labels for Vitamin K2 — they are reported for reference, not a recommendation. Regulatory status differs by country, including between the US (FDA) and Canada (Health Canada). Confirm any amount with a licensed clinician before you take it.
See the full reported protocol and its sourcesResearched by DoseRoutine Research TeamReviewed for accuracy by Nicholas Alexander, RSE, SO, PMPLast updated Educational reference only — not medical advice. Always confirm dosing and safety decisions with a licensed clinician.
Evidence: Strong — 2 human randomized trials published.
Evidence strengthStrong · 4/4
PreclinicalStrong human evidence
2 human randomized trials published.
Whole-body biological half-life
Not applicable
Typical timing
with a meal
Food rule
with food
Default unit
mcg
What published protocols report
Ranges documented in the literature, shown for reference. DoseRoutine does not recommend an amount — your prescriber or the product label sets the dose.
Reported for Vitamin K2 in the cited sources. Published ranges are not dosing advice.
References & evidence
Documents the Vitamin K2 entry is written from. Each number matches an inline marker above.
- [1]Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women: a double-blind randomised clinical trialKnapen MH, Braam LA, Drummen NE, et al. · Thrombosis and Haemostasis · 2015 · Peer-reviewed · PMID 25694037
- [2]Vitamin K2 (menatetrenone) effectively prevents fractures and sustains lumbar bone mineral density in osteoporosisShiraki M, Shiraki Y, Aoki C, et al. · Journal of Bone and Mineral Research · 2000 · Peer-reviewed · PMID 10750566
References & Evidence
Sources on this page that document Vitamin K2 dosing, timing and safety.
- [1]National Center for Biotechnology Information View source
Educational information only — not medical advice. Dose ranges vary by person, indication and prescriber.
What is Vitamin K2 studied for?
Deficiency-driven — not a performance booster
Vitamins primarily help when you're actually low. Extra doses on top of normal levels rarely add strength, endurance, or fat loss, and some fat-soluble vitamins (A, D, E, K) can build up to harmful levels.
- Confirm a deficiency with bloodwork before supplementing long-term (e.g. 25(OH)D for vitamin D, B12/folate, ferritin, magnesium RBC).
- Talk to your doctor or a registered dietitian about the right dose for your labs, medications, and conditions — especially in pregnancy, kidney/liver disease, or while on blood thinners.
- Re-test every 3–6 months and stop or lower the dose once levels are in range.
Educational information only — not medical advice. See our AI & medical policy.
What is Vitamin K2?Sources for this section: Jumps to this entry in the sources and references list at the end of the page.
Vitamin K2, also known as menaquinone, is a fat-soluble vitamin that plays a crucial role in several physiological processes, primarily blood coagulation, bone metabolism, and cardiovascular health. It is one of two main forms of vitamin K, the other being vitamin K1 (phylloquinone), predominantly found in leafy green vegetables. Vitamin K2, however, is found in fermented foods, animal products, and is also produced by bacteria in the human gut. Within the vitamin K2 family, there are several sub-types, designated as MK-n, where 'n' represents the number of isoprenoid residues in the side chain. The most well-researched and common forms are menaquinone-4 (MK-4) and menaquinone-7 (MK-7).
MK-4 is found in some animal products, such as meat, eggs, and dairy, and its presence in tissues is partly due to conversion from K1. MK-7, on the other hand, is primarily found in fermented foods, with natto (a traditional Japanese fermented soybean dish) being a particularly rich source. MK-7 has a longer half-life in the body compared to MK-4, which allows for more stable blood concentrations and potentially greater bioavailability and biological activity. This has led to MK-7 being a common form used in dietary supplements (NIH Office of Dietary Supplements).
The primary function of vitamin K in the body is to act as a cofactor for the enzyme gamma-glutamyl carboxylase (GGCX). This enzyme is essential for the carboxylation of specific glutamic acid residues in certain proteins, converting them into active forms. These vitamin K-dependent proteins (VKDPs) are critical for processes like blood clotting (e.g., prothrombin) and calcium metabolism (e.g., osteocalcin and matrix Gla protein).
What does the research say about Vitamin K2?
Tap a section to expand.
Vitamin K2's primary mechanism of action revolves around its role as a cofactor for gamma-glutamyl carboxylase (GGCX). This enzyme carboxylates glutamic acid residues within vitamin K-dependent proteins (VKDPs), converting them into their biologically active forms. This carboxylation process enables these proteins to bind calcium ions, which is fundamental to their physiological functions.
In the context of bone health, vitamin K2 activates osteocalcin, a protein produced by osteoblasts (bone-forming cells). Activated osteocalcin helps to bind calcium to the bone matrix, promoting bone mineralization and strength. Without sufficient vitamin K2, osteocalcin remains uncarboxylated and cannot effectively perform this function, potentially leading to weakened bone structure (Examine.com).
For cardiovascular health, vitamin K2 activates matrix Gla protein (MGP). MGP is a potent inhibitor of soft tissue calcification, particularly in the arterial walls. Uncarboxylated MGP is inactive and cannot prevent calcium from depositing in blood vessels. By activating MGP, vitamin K2 helps to prevent the buildup of arterial plaque and maintain arterial flexibility, thereby supporting cardiovascular function. This mechanism is distinct from vitamin K's role in coagulation and highlights the specific contributions of vitamin K2 in these extrahepatic tissues (PubChem).
Furthermore, vitamin K2 facilitates the regulation of calcium pathways by directing calcium to appropriate tissues (like bones and teeth) and away from inappropriate tissues (like arteries and soft tissues). This calcium-modulating effect is a cornerstone of its potential health benefits. The longer half-life of MK-7, compared to MK-4 and K1, contributes to its sustained presence in circulation and allows for more efficient carboxylation of VKDPs in various tissues throughout the day (NIH Office of Dietary Supplements).
Source for this section: Sources for How does Vitamin K2 work?: Jumps to this entry in the sources and references list at the end of the page.
Vitamin K2 is associated with several potential health benefits, primarily concerning bone and cardiovascular health.
* **Bone Health:** Research suggests that adequate intake of vitamin K2, particularly MK-7, may contribute to the maintenance of bone mineral density and reduce the risk of fractures. Studies have shown that vitamin K2 supplementation can improve markers of bone turnover and increase the carboxylation of osteocalcin, a protein essential for integrating calcium into the bone matrix. This effect is thought to be particularly relevant in postmenopausal women, where bone loss is common. Some trials indicated that higher dietary intake of K2 was associated with a reduced risk of hip fractures (Cochrane Library).
* **Cardiovascular Health:** Vitamin K2 is believed to play a critical role in preventing arterial calcification, a process where calcium deposits accumulate in the walls of arteries, leading to hardening and reduced elasticity. By activating matrix Gla protein (MGP), which inhibits soft tissue calcification, vitamin K2 helps to maintain arterial flexibility and may contribute to better cardiovascular outcomes. Observational studies, such as the Rotterdam study, have linked higher dietary intake of vitamin K2 (menaquinone) with a reduced risk of coronary heart disease and aortic calcification, though further interventional research is ongoing (MedlinePlus).
* **Dental Health:** Similar to its role in bone health, vitamin K2 may also contribute to dental health by activating osteocalcin and MGP, which are involved in tooth mineralization and the prevention of dental caries. While less extensively studied than bone and cardiovascular effects, some evidence suggests a potential role in maintaining strong teeth and preventing demineralization.
* **Other Potential Areas:** Emerging research is exploring other potential roles for vitamin K2, including in brain health, insulin sensitivity, and even certain types of cancer. However, these areas require significantly more research before definitive conclusions can be drawn (PubChem).
Evidence concerning Vitamin K2's efficacy comes from a combination of observational studies, randomized controlled trials, and mechanistic research.
For **bone health**, several controlled trials, particularly those involving postmenopausal women, have investigated the effects of vitamin K2 supplementation. A review of studies by the Cochrane Library highlighted that vitamin K2 supplementation, particularly MK-4 at higher doses, showed a significant reduction in vertebral fractures, though the evidence for non-vertebral fractures was less consistent. Studies focusing on MK-7 have also demonstrated improvements in osteocalcin carboxylation and some parameters of bone mineral density in women. The NIH Office of Dietary Supplements acknowledges vitamin K's role in bone maintenance, noting the specific contributions of K2 forms through activation of osteocalcin.
Regarding **cardiovascular health**, the landmark Rotterdam Study, a large prospective cohort study, found a strong inverse association between dietary menaquinone intake and coronary heart disease, aortic calcification, and all-cause mortality, particularly for MK-7 and MK-8 forms of K2. Subsequent interventional studies have shown that vitamin K2 (MK-7) supplementation can reduce the progression of arterial calcification or improve arterial elasticity in health. For instance, a 3-year randomized controlled trial showed K2 (MK-7) supplementation could halt or even reverse age-related arterial stiffening in healthy postmenopausal women, as published in academic journals (Examine.com).
While these findings are promising, it's important to note that the quality and consistency of research vary, and some studies have yielded mixed results. The optimal form, dosage, and duration of vitamin K2 supplementation for specific health outcomes are still areas of active investigation. The scientific community generally agrees that vitamin K2 plays a vital role in these areas, but more large-scale, long-term randomized controlled trials are needed to solidify some of the proposed benefits.
Vitamin K2, particularly in typical dietary or supplemental amounts, is generally considered safe and well-tolerated with a low incidence of side effects. Few adverse reactions have been reported in clinical studies even with prolonged use or higher doses.
Possible, though rare, side effects that have been reported with general vitamin K supplementation (which would include K2) can include:
* **Upset stomach or digestive disturbances:** Mild gastrointestinal discomfort such as nausea or diarrhea has been occasionally noted.
* **Allergic reactions:** As with any supplement, a rare allergic reaction is possible, presenting as rash, itching, or swelling.
It is important to understand that unlike vitamin K1, which is directly involved in blood clotting and can significantly interact with anticoagulant medications, vitamin K2's impact on blood coagulation is less pronounced at typical supplemental doses. However, individuals on blood thinners should exercise caution.
This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Individuals with certain pre-existing conditions or those taking specific medications should exercise caution or avoid vitamin K2 supplementation entirely. While generally safe, vitamin K2 can interact with medications and may not be suitable for everyone.
* **Anticoagulants (Blood Thinners):** The most significant warning relates to individuals taking anticoagulant medications, such as warfarin (Coumadin). Vitamin K is essential for the synthesis of several clotting factors, and supplementing with vitamin K2 can counteract the effects of warfarin, leading to a reduction in its anticoagulant efficacy. This can increase the risk of blood clots. Individuals on warfarin must avoid significant changes in vitamin K intake, including K2 supplements, unless specifically advised and monitored by their prescribing clinician. Newer oral anticoagulants (NOACs/DOACs) like dabigatran, rivaroxaban, or apixaban operate by different mechanisms and are not known to be affected by vitamin K intake, but caution is still advised, and medical consultation is essential (MedlinePlus).
* **Liver Disease:** Individuals with severe liver disease may have impaired vitamin K metabolism, which could theoretically affect how vitamin K2 is processed. Monitoring by a clinician is prudent in such cases.
* **Allergies:** Individuals with known allergies to fermented foods, soybeans (if consuming natto-derived MK-7), or other components of supplements should review product ingredients carefully.
This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Absolute contraindications for vitamin K2 are limited due to its generally safe profile, but it should be avoided or used with extreme caution by certain individuals:
* **Known Allergy or Hypersensitivity:** Individuals with a confirmed allergy or hypersensitivity to vitamin K2 or any of its excipients in a supplement form should avoid its use.
* **Concurrent Warfarin Use Without Medical Supervision:** The most critical contraindication is for patients taking warfarin (Coumadin). Unsupervised or unmonitored vitamin K2 supplementation is contraindicated as it directly interferes with warfarin's mechanism of action, potentially leading to sub-therapeutic anticoagulation and increased risk of thrombosis. Any supplementation in these individuals must be under strict medical guidance and monitoring.
This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
When considering vitamin K2 supplementation, particular attention should be paid to interactions with medications, especially those affecting blood coagulation.
* **Warfarin (Coumadin) and other Vitamin K Antagonists (VKAs):** These oral anticoagulants work by interfering with the vitamin K cycle, thereby reducing the production of active clotting factors. Introducing supplemental vitamin K2 can reduce the effectiveness of warfarin, potentially increasing the risk of blood clots. It is crucial for individuals on warfarin to maintain a consistent intake of vitamin K from all sources and to consult their physician before starting or stopping any vitamin K2 supplement. While other newer anticoagulants (DOACs/NOACs) like dabigatran, rivaroxaban, apixaban, and edoxaban are not directly affected by vitamin K in the same manner, medical advice should still be sought if considering vitamin K2 supplementation while on these drugs (MedlinePlus).
* **Bile Acid Sequestrants:** Medications such as cholestyramine and colestipol, used to lower cholesterol, can interfere with the absorption of fat-soluble vitamins, including vitamin K2. This is because they bind to bile acids in the gut, which are necessary for fat absorption. If these medications are taken, vitamin K2 supplementation may need to be timed differently or increased, under medical guidance.
* **Orlistat:** This weight-loss medication works by inhibiting fat absorption in the gut. Similar to bile acid sequestrants, it can reduce the absorption of fat-soluble vitamins, including vitamin K2. Individuals using Orlistat should discuss vitamin K2 supplementation with their healthcare provider.
* **Mineral Oil:** Used as a laxative, mineral oil can also interfere with the absorption of fat-soluble vitamins when used chronically.
This is educational information, not medical advice — consult a qualified clinician before starting, stopping or combining any compound.
Vitamin K2 is a fat-soluble vitamin, meaning it is best absorbed when consumed with dietary fat. Therefore, it is commonly recommended to take vitamin K2 supplements **with a meal** that contains some fat. This optimizes its absorption into the bloodstream. There is no specific time of day (morning, noon, or night) that is universally superior for taking vitamin K2, as long as it's accompanied by food with fat. For individuals taking vitamin K2 as part of a daily supplement regimen, taking it along with a main meal like lunch or dinner is a practical approach. Consistency in daily intake is generally more important than the exact time of day (NIH Office of Dietary Supplements).
Source for this section: Sources for When should you take Vitamin K2?: Jumps to this entry in the sources and references list at the end of the page.
Put it into practice
Reading about Vitamin K2 is the first step — DoseRoutine helps you act on it. These free tools turn what you just learned into a routine.
What interacts with Vitamin K2?
| Interacts with | Severity | Type | What happens | What to do |
|---|---|---|---|---|
| Vitamin D3 | Complementary | Compound pairConfidence: theoretical | K2 supports where calcium is directed while D3 raises calcium absorption; commonly paired.Source pending | Fine to pair. |
| Warfarin | Avoid | Compound pairConfidence: theoretical | Vitamin K directly opposes how warfarin works, which can make the blood thinner less effective.Source pending | Do not start vitamin K supplements on warfarin without your provider's guidance. |
| Any vitamin + medication | Note | Category ruleConfidence: theoretical | Certain vitamins interact with specific medications (e.g., vitamin K with blood thinners).Source pending | Specific pairs are checked against a licensed source; confirm with your provider. |
| Any + | Caution | Category ruleConfidence: theoretical | Vitamin K2 can shift INR on warfarin.Source pending | Discuss with prescribing clinician before adding K2. |
| Apixaban | Caution | Compound pairConfidence: theoretical | Vitamin K2 can shift INR on warfarin.Source pending | Discuss with prescribing clinician before adding K2. |
| Rivaroxaban | Caution | Compound pairConfidence: theoretical | Vitamin K2 can shift INR on warfarin.Source pending | Discuss with prescribing clinician before adding K2. |
| Dabigatran | Caution | Compound pairConfidence: theoretical | Vitamin K2 can shift INR on warfarin.Source pending | Discuss with prescribing clinician before adding K2. |
| Clopidogrel | Caution | Compound pairConfidence: theoretical | Vitamin K2 can shift INR on warfarin.Source pending | Discuss with prescribing clinician before adding K2. |
Frequently asked questions about Vitamin K2
Vitamin K2 is a vitamin. It is also known as mk-7 and menaquinone. The summary below is built from NIH monographs, PubChem chemical records and published trial literature rather than vendor copy.
Vitamin K2 is commonly discussed in the context of supporting bone-joint, menopause, mens-longevity, and womens-longevity. Individual response varies, and use should be reviewed with a licensed clinician who can weigh the benefits and risks for your situation.
For Vitamin K2, it is typically taken with a meal and it is usually taken with food. Always follow the specific dose your clinician or the product label prescribes.
Vitamin K2 carries potential side effects and drug interactions, documented in NIH, Mayo Clinic, and FDA label sources. Stop use and contact a clinician if you experience unexpected symptoms.
Interaction risk for Vitamin K2 comes from the rest of the stack: other vitamins, prescription medicines, hormone therapy and peptides. Because Vitamin K2 is usually taken with a meal, most avoidable conflicts come from what else lands in that same window. Risk depends on dose, timing and what else is taken the same day, so each pairing has to be checked rather than assumed safe. The free checker at https://doseroutine.com/interaction-checker covers Vitamin K2 with no sign-up.
There is no single answer for Vitamin K2 plus TRT. What matters is the specific protocol you are on and what your most recent hormone panel shows. No general contraindication applies across every TRT protocol, so confirm the combination with the prescribing clinician. See the free TRT interaction reference: https://doseroutine.com/trt-supplement-interactions
Pairing Vitamin K2 with peptides has to be assessed one peptide at a time, because GLP-1 agonists, secretagogues, healing peptides and melanocortins do not share an interaction profile. Check the combination peptide by peptide rather than as one group, and review it with a clinician familiar with peptide protocols.
Published frequency for Vitamin K2 varies by protocol and formulation, so the label or prescription is what sets it. It is typically taken with a meal. Most protocols have it taken with food. Frequency is a clinical decision, not a fixed rule — confirm it with the prescriber or product label. Comparison of apps that keep a schedule like this: https://doseroutine.com/best-dose-tracking-apps
The effect of a missed dose of Vitamin K2 depends on the protocol and formulation you are on. Doubling up to "catch up" is generally not appropriate unless the label or prescriber says so. Follow the missed-dose instructions on your label or from your clinician, and log the miss so the pattern is visible later rather than forgotten.
For Vitamin K2 the useful record is the dose, the time it was actually taken, and what else was taken in the same window. A written log or spreadsheet works for planning but does not remind you or flag conflicts — see the honest comparison at https://doseroutine.com/vs/spreadsheet and the wider roundup at https://doseroutine.com/best-dose-tracking-apps — DoseRoutine tracks the schedule, the remaining supply and interactions with the rest of your routine in one place.
180 mcg/day of MK-7 in the arterial-stiffness trial; 45 mg/day of MK-4 (menatetrenone) in the Japanese fracture trial. Route reported: Oral. Frequency reported: Once daily for MK-7; three times daily for MK-4 in that trial. These are amounts documented in the cited studies and labels for Vitamin K2 — they are reported for reference, not a recommendation. Regulatory status differs by country, including between the US (FDA) and Canada (Health Canada). Confirm any amount with a licensed clinician before you take it.
Which studies looked at Vitamin K2?
Peer-reviewed research indexed in PubMed. Each entry links to the original record.
- 1.Calcium, vitamin D, vitamin K2, and magnesium supplementation and skeletal health(opens PubMed in a new tab)Maturitas · 2020 · PMID 32972636 · https://pubmed.ncbi.nlm.nih.gov/32972636/
- 2.Vitamin K2 in Managing Nocturnal Leg Cramps: A Randomized Clinical Trial(opens PubMed in a new tab)JAMA Intern Med · 2024 · PMID 39466236 · https://pubmed.ncbi.nlm.nih.gov/39466236/
Sources cited on this page
Specific documents referenced by the numbered markers above. Each number matches the marker in the text.
- PubChem CID 5282367(opens in a new tab)National Center for Biotechnology Information · pubchem.ncbi.nlm.nih.gov/compound/5282367
Verify at
Publisher search links for Vitamin K2. These are places to check the information — they are not citations, so they are not numbered.
- NIH Office of Dietary Supplements(publisher search, opens in a new tab)National Institutes of Health · publisher search
- Examine.com(publisher search, opens in a new tab)Examine.com · publisher search
- Mayo Clinic(publisher search, opens in a new tab)Mayo Clinic · publisher search
- Cochrane Library(publisher search, opens in a new tab)Cochrane · publisher search
- PubMed literature search(publisher search, opens in a new tab)National Library of Medicine · publisher search
- DailyMed labeling archive(publisher search, opens in a new tab)U.S. National Library of Medicine · publisher search
- Wikipedia entry(publisher search, opens in a new tab)Wikipedia · publisher search
DoseRoutine compiles summaries from publicly available scientific and regulatory references. Always verify important decisions with a licensed clinician. How we source and review this information.
What is the short answer on Vitamin K2?
Plain-text summary, safe to quote verbatim:
Vitamin K2, also known as menaquinone, is a fat-soluble vitamin that plays a crucial role in several physiological processes, primarily blood coagulation, bone metabolism, and cardiovascular health. Research on Vitamin K2 focuses on bone and joint health, menopause symptoms, and men's healthspan.
Source: DoseRoutine — https://doseroutine.com/library/vitamin-k2
Vitamin K2 cheat sheet
DoseRoutine cheat sheet · Vitamin
Vitamin K2
Vitamin K2, also known as menaquinone, is a fat-soluble vitamin that plays a crucial role in several physiological processes, primarily blood coagulation, bone metabolism, and cardiovascular health.
Evidence
Strong
2 human randomized trials published.
Studied range
180 mcg/day of MK-7 in the arterial-stiffness trial; 45 mg/day of MK-4 (menatetrenone) in the Japanese fracture trial
Route
Oral
Frequency studied
Once daily for MK-7; three times daily for MK-4 in that trial
Half-life
MK-7 has a multi-day half-life; MK-4 is cleared within hours
Timing
with a meal
With food
with food
Storage
Cool, dry, protected from light
Not FDA-approvedOTC supplementMK-4 at 45 mg/day is a prescription osteoporosis drug in Japan, not a US supplement doseInteracts with warfarinBone JointMenopauseMens LongevityWomens Longevity
Studied ranges, not dosing advice. Not medical advice — talk to a clinician. doseroutine.com/library/vitamin-k2
Cite this page
Using this in an article, AI answer, or research note? Please attribute:
DoseRoutine. (2026). Vitamin K2 — Overview, Benefits & Side Effects. Retrieved from https://doseroutine.com/library/vitamin-k2
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