Vitamin K
Phylloquinone (K1) / Menaquinone (K2)
Moderate
Vitamin K exists in two main forms: K1 (from plants, primarily for clotting) and K2 (from fermented foods and animal products, important for bone and cardiovascular health). K2 (especially MK-7) has gained attention for its role in directing calcium to bones rather than arteries.
How It Works
Vitamin K activates proteins through gamma-carboxylation:
- Coagulation Factors: Activates factors II (prothrombin), VII, IX, and X, essential for blood clotting.
- Osteocalcin: K2 activates this bone protein, enabling it to bind calcium for bone mineralization.
- Matrix Gla Protein (MGP): K2 activates MGP, which inhibits arterial calcification.
- Protein S: Anticoagulant protein also requiring vitamin K activation.
- K1 vs K2: K1 preferentially used for clotting; K2 has higher tissue distribution and longer half-life.
Natural Food Sources
| Food | Amount per Serving |
|---|---|
| Natto (fermented soybeans) | 1,103 mcg K2 per 3 oz |
| Kale | 547 mcg K1 per cup |
| Spinach (raw) | 145 mcg K1 per cup |
| Broccoli | 110 mcg K1 per 1/2 cup |
| Brussels sprouts | 109 mcg K1 per 1/2 cup |
| Hard cheese | 25-75 mcg K2 per oz |
| Egg yolk | 15-30 mcg K2 per yolk |
Safety Information
Contraindications
- Warfarin therapy - vitamin K directly counteracts warfarin; keep intake consistent, don't start supplements without MD guidance
- History of blood clots (while on anticoagulants)
Potential Side Effects
- Very safe - no known toxicity from food or supplements (rare)
- Theoretical clotting risk if taking anticoagulants (uncommon)
Disclaimer: The information provided is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare provider before starting any supplement regimen.