Menaquinone (vitamin K2)

Vitamins. γ-glutamyl carboxylase cofactor

ATC code: B02BA-K2

Brand names – supplements: Quality of Life Vitamin K2 MenaQ7, Thorne Vitamin K, Life Extension Super K, Doctor's Best Vitamin K2Supplements are not tested in clinical trials and are not registered as medications.

Updated 19 Aug 2026 · Methodology

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Anti-aging and longevity

Not recommended

Menaquinone (vitamin K2) is a form of vitamin K often promoted as a supplement for anti-aging and longevity. Clear benefit for this use has not been shown: there is no solid evidence that K2 extends lifespan or slows aging. Lifespan responds far more to managing blood pressure and blood sugar, not smoking, staying physically active, and sleeping well – worth discussing with your doctor. Important: vitamin K reduces the effect of warfarin and other vitamin K antagonists; patients on these anticoagulants, including those with a mechanical heart valve, must not take vitamin K supplements without medical agreement.

Sources

Cochrane: Vitamin K supplementation for the primary prevention of cardiovascular disease (2020)

Cardiovascular calcification prevention

Not recommended

Menaquinone (vitamin K2) is a fat-soluble vitamin involved in calcium metabolism. It's promoted as a supplement to prevent vascular calcification, with the idea that K2 routes calcium into bone rather than the artery wall. So far this use hasn't shown convincing benefit – there's no solid evidence that taking K2 reduces vascular calcification or cardiovascular risk. The substance itself is harmless at these doses. What actually lowers vascular calcification is managing blood pressure, lipids and blood sugar, quitting smoking and staying physically active – worth discussing with your doctor. Don't take menaquinone in place of treatment with proven benefit, since that risks missing the care you need. Important: vitamin K reduces the effect of warfarin and other vitamin K antagonists; patients on these anticoagulants, including those with a mechanical heart valve, must not take vitamin K supplements without medical agreement.

Sources

Cochrane: Vitamin K supplementation for the primary prevention of cardiovascular disease (2020)

Postmenopausal osteoporosis

Not recommended

2009 approved the claim “vitamin K contributes to bone health maintenance” for labelling. Evidence on oral K2 in postmenopausal osteoporosis is limited: the 2008 Booth RCT did not show a significant effect on bone mineral density or fractures. Endocrine Society 2019 does not include K2 in osteoporosis treatment standards. Standard therapy: bisphosphonates, denosumab, teriparatide + calcium + vitamin D. Important: vitamin K reduces the effect of warfarin and other vitamin K antagonists; patients on these anticoagulants, including those with a mechanical heart valve, must not take vitamin K supplements without medical agreement.

Japanese guidelines for postmenopausal osteoporosis include MK-4 at 45 mg daily, but this is a narrow local practice not supported by international consensus.

Sources

ICD-10: M81.0 · ICD-11: FB83.11

How to read tiers A–F

AStrong evidence – first or second line in international guidelines
BRecommended in selected cases
CStudy data contradict each other
DBenefit not proven, no documented harm
FDocumented harm, or risk without benefit

Mechanism of action

Vitamin K2 (menaquinone, mainly MK-7 and MK-4) is a γ-glutamyl carboxylase cofactor. It activates Gla proteins: osteocalcin (bone mineralisation), matrix Gla protein (inhibitor of vascular calcification), and clotting factors II, VII, IX, X. Unlike vitamin K1 (phylloquinone) with a predominant role in coagulation, K2 has a more pronounced effect on bone and vascular calcium metabolism. The long half-life of MK-7 (72 hours) allows once-daily dosing.

Safety

Contraindications

Concomitant warfarin therapy – requires anticoagulant dose adjustment
Hypersensitivity to components
Severe hepatic impairment

Serious adverse effects

Destabilisation of warfarin anticoagulation with thrombotic event risk

Common adverse effects

Side effects at standard doses are rare

Uncommon adverse effects

Mild dyspepsia
Allergic reactions (rash, pruritus)

Pregnancy: can you take Menaquinone (vitamin K2)?

Pregnancy data are insufficient. Vitamin K at physiological doses from dietary sources is safe. Supplemental K2 in pregnancy is not recommended.

Breastfeeding: can you take Menaquinone (vitamin K2)?

Low K2 content in breast milk is physiological. Newborns routinely receive a single dose of vitamin K1 to prevent haemorrhagic disease of the newborn. Maternal K2 supplementation does not affect infant status.

Calculate RID Full profile on NIH LactMed ↗

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Practical notes

Timing and administration

Take with food, preferably one containing fat – K2 is fat-soluble and absorption increases 2–3 fold with dietary fat. MK-7 has a long half-life (72 hours) and is taken once daily. MK-4 is taken 2–3 times daily.

Dose titration

Standard supplement dose: 90–180 µg MK-7 daily. RCTs evaluating efficacy used 180–360 µg MK-7 or 45 mg MK-4 daily. Daily allowance for vitamin K (total K1 and K2): 90–120 µg in adults. Most people on a varied diet meet daily needs from food.

Monitoring

No special monitoring at standard doses. In patients on warfarin, vitamin K intake (including K2) substantially changes anticoagulation stability – warfarin dose adjustment under INR monitoring is required. In patients on direct oral anticoagulants (rivaroxaban, apixaban, dabigatran), vitamin K does not affect the effect.

Food and drinks

Dietary K2 sources: fermented foods (natto – the richest source, hard cheese, aged dairy), chicken egg yolk, liver, chicken meat. Fermented soybean natto contains 800–1,000 µg MK-7 per 100 g. In people who regularly consume natto, K2 deficiency is extremely rare. Vegetarians without fermented foods in the diet have lower K2 levels.

Common myths

Myth: “K2 prevents vascular calcification and heart attacks”. Fact: large RCTs did not confirm an effect on cardiovascular morbidity or mortality. Marketing outpaces science.

Myth: “K2 must be taken with D3”. Fact: D3+K2 combinations in supplements are a marketing approach. Evidence that concurrent intake improves vitamin D effects or prevents hypercalcaemia is absent. In patients on adequate D3 doses with a varied diet, additional K2 is not needed.

Myth: “MK-7 is significantly better than MK-4”. Fact: MK-7 has a longer half-life and is more convenient. Clinical advantages over MK-4 in the general population are not proven. Japanese osteoporosis guidelines actually use MK-4.

Drug–drug interactions

1 pair found. Sorted from critical to minor.

MajorWarfarinVitamin K antagonist anticoagulants

Mechanism

Menaquinone is vitamin K just as phylloquinone is, with a longer plasma half-life. It antagonises warfarin by the same mechanism, and its presence in calcium plus vitamin D bone complexes means it enters the regimen without the patient registering it as vitamin K.

Symptoms

INR falling below range in the weeks after starting a bone complex, with no change in diet or warfarin dose.

Management

Check the composition of any bone or joint complex before taking it with warfarin: K2 often appears in the small print. If it is already in use, do not stop it abruptly; check the INR more frequently while the decision is made with the prescriber.

Sources

NIH Office of Dietary Supplements: Vitamin K – Health Professional Fact Sheet (2025)

Pair details →Warfarin →

Check interaction with another drug

Opens the checker prefilled with this drug. Pick the second one from your regimen.

Open checker

Summary of a multi-drug list →

Medicine list: everything you take in one place →

Frequently asked

What is Menaquinone (vitamin K2) used for?

Menaquinone (vitamin K2) is evaluated for the following indications with varying evidence strength: Anti-aging and longevity (evidence tier D), Cardiovascular calcification prevention (evidence tier D), Postmenopausal osteoporosis (evidence tier D). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Menaquinone (vitamin K2)?

Common side effects of Menaquinone (vitamin K2) (≥ 1 in 100): Side effects at standard doses are rare. See the Safety section for uncommon and serious reactions.

Is Menaquinone (vitamin K2) safe during pregnancy?

Pregnancy data are insufficient. Vitamin K at physiological doses from dietary sources is safe. Supplemental K2 in pregnancy is not recommended.

Is Menaquinone (vitamin K2) compatible with breastfeeding?

Who should not take Menaquinone (vitamin K2)?

Menaquinone (vitamin K2) is contraindicated in: Concomitant warfarin therapy – requires anticoagulant dose adjustment; Hypersensitivity to components; Severe hepatic impairment. Full list in the Safety section.

“K2 prevents vascular calcification and heart attacks”

large RCTs did not confirm an effect on cardiovascular morbidity or mortality. Marketing outpaces science.

“K2 must be taken with D3”

D3+K2 combinations in supplements are a marketing approach. Evidence that concurrent intake improves vitamin D effects or prevents hypercalcaemia is absent. In patients on adequate D3 doses with a varied diet, additional K2 is not needed.

“MK-7 is significantly better than MK-4”

MK-7 has a longer half-life and is more convenient. Clinical advantages over MK-4 in the general population are not proven. Japanese osteoporosis guidelines actually use MK-4.

Other drugs in this group

Eltrombopag, Menaquinone-7, Phytomenadione, Tranexamic acid