Check before you startThis one has documented interactions with medication classes where the consequences are serious. If you take any prescription medicine, run it past a pharmacist before starting.
How long to take it
Ongoing alongside vitamin D, since the dietary sources are genuinely rare in most diets.
Who it's actually for
Anyone supplementing vitamin D long-term, and people managing bone density.
Safe upper limit
UnverifiedNone established
No formal upper limit, but the warfarin interaction is the hard constraint, not toxicity. No EFSA/NIH UL exists for vitamin K generally, but this needs direct confirmation. The warfarin interaction is the more load-bearing fact here and needs its own check.
No source attached yet. Treat this as a starting point, not a citation, until reviewed.
Interactions to know about
- Blood thinners / antiplatelets — Warfarin, apixaban, rivaroxaban, clopidogrel, aspirin
Other supplements:
Run your full list through the interaction check.
Practical notes
- MK-7 stays in the blood far longer than MK-4 — once daily is enough.
- Take with fat.
- If you are on warfarin, do not start or stop this without telling your prescriber.