Vitamin K2 MK-7: Uses, Benefits, Dosage & Safety
Last updated: August 2026 · Reviewed by the FactoWiki Editorial Team for clarity and source accuracy
Quick summary
MK-7 is the long-chain form of vitamin K2 with a half-life measured in days rather than hours, making once-daily dosing practical. Its bone evidence is mixed — one positive trial, one null — and it has a serious anticoagulant interaction that must not be overlooked.
What is Vitamin K2 MK-7?
Menaquinone-7, produced by bacterial fermentation — natto, the Japanese fermented soybean dish, is the richest food source. It differs from MK-4 in side-chain length, which gives it a much longer half-time in circulation: roughly 3 days against about 1–2 hours for MK-4.
What Vitamin K2 MK-7 is commonly used for
Bone density, arterial calcification, and commonly combined with vitamin D3 on the rationale of directing calcium to bone rather than soft tissue.
How Vitamin K2 MK-7 works
Vitamin K is required to carboxylate two proteins: osteocalcin, which binds calcium into bone matrix, and matrix Gla protein, which inhibits calcification in arteries. Undercarboxylated forms of both are associated with worse bone and vascular outcomes. That mechanism is well characterised.
What the evidence says
Each claim below is tied to the specific study behind it, rather than to a general reading list.
- A three-year trial of MK-7 at 180 mcg reported reduced bone loss in postmenopausal women, but a later three-year trial at 375 mcg found no difference in bone mineral density versus placebo — so the bone evidence is mixed rather than settled. Knapen et al., Osteoporosis International, 2013 (positive) and Rønn et al., Osteoporosis International, 2021 — PMID 33030563 (null) — two randomised, double-blind, placebo-controlled trials reaching different conclusions. (PubMed)
- MK-7 has substantially longer half-life and better bioavailability than MK-4. Sato et al., Nutrition Journal, 2012 — pharmacokinetic comparison. (PubMed)
- Vitamin K carboxylates osteocalcin and matrix Gla protein. Booth, Annual Review of Nutrition, 2009 — review of vitamin K biology. (PubMed)
Typical dosage used in studies
Trials use 90–360 mcg daily, with 180 mcg common. The long half-life means once-daily is sufficient, unlike MK-4 which needs multiple daily doses.
Side effects and safety
Well tolerated at these doses, with no established toxicity. Vitamin K does not have a defined upper limit for the reason that excess is not readily stored.
Medication interactions and who should avoid Vitamin K2 MK-7
Medication & safety check
This is the important part. Vitamin K directly antagonises warfarin, and even modest supplemental amounts can change your INR. Anyone on warfarin must not start K2 without their anticoagulation clinic knowing. The interaction is with warfarin specifically rather than the DOACs, but tell your doctor regardless.
General information, not personal medical advice. If you take any medication, confirm it is safe to combine with Vitamin K2 MK-7 with your doctor or pharmacist first.
Sources & further reading
The claim-level citations above are drawn from these sources:
- Knapen et al., Osteoporosis International, 2013 (positive) and Rønn et al., Osteoporosis International, 2021 — PMID 33030563 (null) — two randomised, double-blind, placebo-controlled trials reaching different conclusions — find on PubMed
- Sato et al., Nutrition Journal, 2012 — pharmacokinetic comparison — find on PubMed
- Booth, Annual Review of Nutrition, 2009 — review of vitamin K biology — find on PubMed
- NIH Office of Dietary Supplements
- NIH National Center for Complementary and Integrative Health
Frequently asked questions
MK-4 or MK-7?
MK-7 for practical dosing — it lasts days, so once daily works. MK-4 has Japanese fracture data but at very high doses (45 mg) requiring multiple daily doses.
Can I take it with warfarin?
Not without telling your anticoagulation clinic. Vitamin K directly opposes warfarin and can push your INR out of range. This is a genuine safety issue, not a precaution.
Is D3+K2 better than D3 alone?
The rationale is sound and the outcome evidence that the combination beats D3 alone is limited. It is reasonable rather than proven.
Part of a wider guide
Vitamin K2 MK-7 is one form of Vitamin K2. This page covers what is specific to this form — absorption, tolerability, dosing and who it suits. For the underlying nutrient itself, its overall evidence base and general safety, read the Vitamin K2 guide.
Where you'll find Vitamin K2 MK-7
Vitamin K2 MK-7 appears in Vitamins & Bone Health formulas. Browse the supplement guides to see the products we review, each with a full breakdown of formula, pricing and safety.
Related ingredients to explore
Ingredients often studied or formulated alongside Vitamin K2 MK-7.
General information, not medical advice.