Vitamin K1, the leafy-green form of vitamin K, is a nutrient sold as a dietary supplement for bone and artery health, needed to activate clotting proteins and, less reliably, bone and vessel proteins. Its one firmly established use is correcting clotting problems. Evidence for bones, arteries and longer life is uncertain, from few trials or observation. Safety is reassuring for oral use; the main hazard is for warfarin-type drug users. (Full Review)
| Marker | Target | Why |
|---|---|---|
| INR (warfarin users only) | Within the prescribed therapeutic range (standard reference range 0.8–1.2) | Safety check: a falling INR means K1 is overriding anticoagulation |
| Plasma phylloquinone | >1.0 nmol/L | Confirms intake and absorption |
| Triglycerides (lipid panel) | Not specified in the ER | Shapes blood K1 readings |
| dp-ucMGP (dephospho-uncarboxylated matrix Gla protein) | No established target; track the decline from the individual's own baseline | Falls as K1 activates MGP |
| %ucOC (percentage undercarboxylated osteocalcin) | No established target; track the decline from the individual's own baseline | Falls dose-dependently with K1 |
| CAC score (coronary artery calcium, CT-based) | No established target; track change from the individual's own baseline | Tracks vascular calcification progression |
Cadence: Baseline before starting supplemental K1; warfarin users: INR at 1 week and 4 weeks after any change in K1, then at the anticoagulation clinic's usual interval; others: phylloquinone and dp-ucMGP at 3 months, then every 12 months; repeat calcium scan no sooner than every 2–3 years