Rankings / Essentials — Vitamins & Minerals

Vitamin K1 (phylloquinone)

Essentials · Vitamin

Tier A+

Reviewed by Read Off Label · Last reviewed · How we grade

vitaminotc
8.4 / 10
Tier A+
Ev 8 Bn 8 Sf 9

Bottom line

Read Off Label grades Vitamin K1 (phylloquinone) as A+ (8.4/10) based on strong evidence, strong benefit magnitude, and a low-risk safety profile.

Confusion with K2 is the dominant clinical error — K1 supplementation does not replicate K2's arterial calcification or osteocalcin activation data.

Typical use: 90-120 mcg/day RDA from dark leafy greens (kale, spinach, broccoli); 5-10 mg PO or 1-10 mg IV for warfarin reversal — Rx (IV/IM Phytonadione); OTC.

What this is

Confusion with K2 is the dominant clinical error — K1 supplementation does not replicate K2's arterial calcification or osteocalcin activation data. Newborn IM 1 mg K1 prophylaxis is standard. A consistent dietary K1 intake matters for warfarin patients more than supplementation.

Mechanism

Cofactor for gamma-glutamyl carboxylase, which activates vitamin K-dependent clotting factors (II, VII, IX, X, protein C/S) in the liver; minimal extrahepatic distribution compared with K2 menaquinones

Dose & route

90-120 mcg/day RDA from dark leafy greens (kale, spinach, broccoli); 5-10 mg PO or 1-10 mg IV for warfarin reversal

Citations

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Common questions

Does Vitamin K1 (phylloquinone) work?
Read Off Label rates the evidence for Vitamin K1 (phylloquinone) as Strong and the benefit magnitude as strong, producing an overall grade of A+ (8.4/10). Confusion with K2 is the dominant clinical error — K1 supplementation does not replicate K2's arterial calcification or osteocalcin activation data.
Is Vitamin K1 (phylloquinone) safe?
Vitamin K1 (phylloquinone) has a low risk profile in published human data. Legal status: Rx (IV/IM Phytonadione); OTC (oral). This is not medical advice — see the disclaimer.
What is the typical dose for Vitamin K1 (phylloquinone)?
90-120 mcg/day RDA from dark leafy greens (kale, spinach, broccoli); 5-10 mg PO or 1-10 mg IV for warfarin reversal
How does Vitamin K1 (phylloquinone) work?
Cofactor for gamma-glutamyl carboxylase, which activates vitamin K-dependent clotting factors (II, VII, IX, X, protein C/S) in the liver; minimal extrahepatic distribution compared with K2 menaquinones

This is an independent synthesis of published research by a non-clinician. Scores are opinions supported by citations, not prescriptions. See the full disclaimer and methodology for how this score was produced and what it does and doesn't mean.