Vitamin K1 comes mainly from leafy greens. Supplementing it reliably switches on the calcium-handling proteins in bone and artery walls, and people with more of it live longer in large population studies — but supplement trials on bone density, fractures, and artery calcium have mostly been negative. Safety is unusually favorable; it directly cancels older blood thinners. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Plasma phylloquinone (vitamin K1) | >1.0 nmol/L | Direct measure of circulating supply |
| Dephosphorylated-uncarboxylated matrix Gla protein (dp-ucMGP) | <400 pmol/L | Functional marker of vascular vitamin K sufficiency |
| Undercarboxylated osteocalcin (%ucOC) | <20% of total osteocalcin | Functional marker of skeletal vitamin K sufficiency |
| Prothrombin time / INR | 0.9–1.1 (not on an anticoagulant) | Detects frank deficiency and flags anticoagulant interference |
| PIVKA-II | Below the assay's detection cutoff | Earliest sensitive marker of hepatic vitamin K deficiency |
| 25-hydroxyvitamin D | 40–60 ng/mL | Vitamin D drives production of the proteins vitamin K1 activates |
| Coronary artery calcium score | 0, or no progression from personal baseline | Structural endpoint the vascular hypothesis predicts |
| Bone mineral density (DEXA T-score) | ≥ -1.0, or no decline from personal baseline | Structural endpoint for the skeletal hypothesis |
Cadence: Clotting time at 4 weeks, then carboxylation markers at 3 months once a stable dose is reached; plasma phylloquinone and functional markers every 6–12 months; calcium score and bone density every 2–3 years.