Vitamin K1 (Phylloquinone)
Commonly used for
Healthy AgingBlood Clotting Support
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What is it? / Overview
Vitamin K1 is required to activate clotting factors that allow normal blood coagulation. Supplementation is most beneficial for correcting deficiency and is not routinely recommended for healthy adults consuming adequate dietary vitamin K.
How is it used? / Administration
Form: Phylloquinone (Vitamin K1)
Typical dose studied: 90 mcg/day (women), 120 mcg/day (men); higher only under medical supervision
Timing: With fat-containing meal
Vitamin K1 found primarily in leafy green vegetables. Consistency of intake more important than avoidance for patients taking warfarin.
How well does it work? / Evidence
✓ Well-established
Who should avoid it?
Interacts with: Warfarin and vitamin K antagonists — maintain consistent intake rather than avoiding vitamin K
Already taking it? If taking warfarin discuss any supplementation with prescribing clinician before changes.
Research & references
Andrès E et al. (2024). Fat-soluble vitamins review. Journal of Clinical Medicine. Lees JS et al. (2019). Vitamin K status and vascular disease meta-analysis. Heart. NIH Office of Dietary Supplements: Vitamin K Fact Sheet.
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