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Vitamin

Vitamin K1 (Phylloquinone)

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Vitamin K1 (Phylloquinone). Leafy-green K1 essential for hepatic coagulation factors.

How it works. Cofactor for γ-glutamyl carboxylase activating clotting factors II, VII, IX, X.

What the research supports. 1 graded claims. Strongest: Required for normal coagulation (strong).

How much to take. Typical dose: 90–120 mcg.

Side effects and interactions. 1 medication interaction listed. Serious: Antagonizes warfarin.

Stacking. Pairs well with Omega-3, CoQ10.

Common forms. Available as Capsule or softgel, Sublingual tablet or liquid, Methylated active form for sensitive individuals, Multivitamin matrix.

Key studies. 8 studies cited. The strongest are listed with links to PubMed.

Community. Experiences from people who have tried Vitamin K1 (Phylloquinone). Anecdotes are not medical advice.

Vitamin K1 (Phylloquinone). Leafy-green K1 essential for hepatic coagulation factors.

Molecular structureC31H46O2 · 450.7 g/mol

What it is

Leafy-green K1 essential for hepatic coagulation factors.

Food sources

Whole-food sources (animal products for fat-soluble and B-complex vitamins; produce for water-soluble vitamins)Fortified foods (cereals, dairy, plant milks, nutritional yeast)Multivitamins or stand-alone supplements in synthetic or food-derived form

Goals

Cardiovascular HealthBone HealthGeneral Wellness

How it works

Cofactor for γ-glutamyl carboxylase activating clotting factors II, VII, IX, X.

Pathways

  • Cofactor for γ-glutamyl carboxylase activating clotting factors II, VII, IX, X

Effects

  • +Required for normal coagulation supports

What the research supports

Required for normal coagulationstrong

Strong: consistent results across large trials or meta-analyses. Moderate: several trials, mostly positive. Limited: small or mixed studies. Preclinical: animal or cell research only.

Typical dose
90–120 mcg
TimingConsistent daily timing recommended; split larger doses if GI tolerance is a concern.
With foodWith fat
Best formMost evidence is based on the capsule or softgel form.
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Side effects & interactions

Serious

  • Antagonizes warfarin

Medication interactions

Warfarinsevere

Keep K1 intake consistent.

Check any supplement–medication combination with your pharmacist before starting.

Combines with

Pairs well

  • Omega-3Anti-inflammatory cardiovascular synergy.
  • CoQ10Supports mitochondrial energetics in cardiac tissue.

Common forms

  • Capsule or softgel
  • Sublingual tablet or liquid
  • Methylated active form for sensitive individuals
  • Multivitamin matrix

Key studies

8 studies cited in total.

PubMed: Vitamin K1 (Phylloquinone) — Required for normal coagulation ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching Vitamin K1 (Phylloquinone) and "Required for normal coagulation". Filter by RCT, meta-analysis, or year on the results page.

PubMed: Vitamin K1 (Phylloquinone) — randomized controlled trial ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching Vitamin K1 (Phylloquinone) and "randomized controlled trial". Filter by RCT, meta-analysis, or year on the results page.

PubMed: Vitamin K1 (Phylloquinone) — meta-analysis ↗
Systematic review · PubMed (NLM) · 2026

Opens current human and preclinical literature matching Vitamin K1 (Phylloquinone) and "meta-analysis". Filter by RCT, meta-analysis, or year on the results page.

Discussion

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