Vitamin K1
Also known as: Phytomenadione, Phylloquinone, Phytonadione, Menatetrenone K1
Effective Dosage
No established dose from provided studies for general supplementation; clinical uses vary widely (0.3–10 mg depending on indication)
What the Science Says
Vitamin K1 (phytomenadione) is a fat-soluble vitamin found naturally in leafy green vegetables. Its best-established role is enabling normal blood clotting — it activates proteins that stop bleeding, and is used clinically to reverse dangerous coagulopathy caused by anticoagulant rodenticide poisoning or certain antibiotics. Some research in hemodialysis patients suggests high-dose intravenous K1 may slow the progression of coronary artery calcification, though this evidence is preliminary and specific to kidney disease patients.
What It Doesn't Do
Not proven to build or preserve bone density in general populations — a large dialysis trial found mixed and site-specific effects, not a clear benefit. No evidence from provided studies that it improves blood sugar or prevents diabetes. Don't expect it to replace medical treatment for bleeding disorders. No data supporting it as a general anti-aging or cardiovascular supplement for healthy adults.
Evidence-Based Benefits
Vitamin K1 is essential for coagulation factor activation and is the established antidote for anticoagulant rodenticide poisoning (brodifacoum) and antibiotic-induced coagulopathy (PMID: 41369295, 41853580, 41034709, 41221760). In neonates, intramuscular K1 prophylaxis at birth (0.5–1 mg) effectively prevents vitamin K deficiency bleeding, with 1 mg and 0.5 mg doses showing superior sufficiency at 28 days compared to 0.3 mg (PMID: 36343740, 39912270). In hemodialysis patients, IV K1 supplementation (10 mg thrice weekly) reduced progression of coronary artery calcifications by approximately 55% compared to placebo over 12 months, though the result was borderline significant (PMID: 39680321).
Moderate EvidenceEffective at: No established dose from provided studies for general supplementation; clinical/therapeutic doses vary widely by indication (0.3–1 mg IM for neonates; 10 mg IV for hemodialysis patients; oral doses studied in diabetes context)
Source: auto-research
Absorption & Bioavailability
Unknown from provided studies for oral supplementation in healthy adults. Intramuscular and intravenous routes are used in clinical settings for reliable delivery. Oral absorption is fat-dependent and not characterized in the provided papers.
Red Flags to Watch For
- Interacts with blood thinners like warfarin — even small dietary changes in K1 intake can destabilize anticoagulation therapy
- Some antibiotics (e.g., cefoperazone/sulbactam) can deplete vitamin K and cause dangerous coagulation dysfunction — do not self-supplement without medical guidance if on these drugs
- High-dose IV K1 studies are in hemodialysis patients — results cannot be generalized to healthy adults
- Neonatal dosing studies show that more is not always better — 2 mg IM was not superior to 1 mg in preventing vitamin K deficiency bleeding in newborns
- Bone health benefits are inconsistent — one RCT found accelerated bone loss at one skeletal site with vitamin K supplementation in dialysis patients
Products Containing Vitamin K1
See how Vitamin K1 is used in these analyzed products:
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-04-06