Compound or practice · Supplement
Vitamin K1
The clotting vitamin from leafy greens — the reason warfarin patients must keep their greens consistent.
- Overall grade
- Grade B
- Last revised
- 2
- graded outcomes
- 0
- references listed
A structured monograph in Prometheus's bundled library. Its grades are the monograph's own reading of the evidence, not a peer-reviewed review.
2 at grade A — 2 graded rows
What is known
Each outcome with its grade (how strong the evidence is, A to D), the size of the effect where the entry records one, and how often studies agree.
- Blood clottingEvidence grade A
Definitional
Largehigh
- Warfarin reversal (clinical)Evidence grade A
Medical use
Largehigh
What is uncertain
Read off the same rows as above. Nothing here is added that the entry does not itself record.
- Caution with Anticoagulants (warfarin): Directly antagonizes warfarin — keep intake consistent, never swing it.
Interactions
Documented pairings with supplements and medicines. A medicine on this list is a conversation for whoever prescribes it.
Anticoagulants (warfarin)Caution
Directly antagonizes warfarin — keep intake consistent, never swing it.
The evidence in words
What it is
Vitamin K1 (phylloquinone) is the plant form of vitamin K, essential for blood clotting and distinct from bone-directed K2.
How it works
K1 activates clotting factors in the liver via carboxylation; it is the direct antagonist of warfarin, which blocks that recycling.
What the evidence shows
Grade A for its clotting role and for reversing warfarin over-anticoagulation (a medical use). Dietary deficiency is rare. Its practical relevance for most people is the warfarin interaction: swinging green-vegetable intake destabilizes anticoagulation.
How to use it
Obtained from leafy greens; supplementation is rarely needed outside clinical settings. On warfarin, keep intake steady rather than avoiding greens.
Safety & interactions
Very safe; the key issue is consistency for anyone on vitamin-K-antagonist anticoagulants. warfarin — Directly antagonizes warfarin — keep intake consistent, never swing it.
Bottom line
You get enough from greens. If you take warfarin, the rule is steady, consistent vitamin K — not avoidance.
How it is used
As the entry records it, from the studies it summarises. Not a recommendation for you — doses that suit a trial population may not suit you.
- Food-first
- Leafy greens; keep intake steady on warfarin.
Related reading
Entries that share this one's tags or conditions.
- Vitamin K1 for Blood clottingEvidence grade A — DefinitionalEvidence grade A
- Vitamin K1 for Warfarin reversal (clinical)Evidence grade A — Medical useEvidence grade A
- Vitamin K1: dosage and how to take itLeafy greens; keep intake steady on warfarin.Evidence grade B
- Vitamin K1: side effects, safety & interactionsVery safe; the key issue is consistency for anyone on vitamin-K-antagonist anticoagulants.Evidence grade B
Sources
This entry lists no references of its own.
Last revised . A grade is this entry's reading of the evidence, not medical advice.