Vitamin K1 (Phylloquinone)

Summary

Vitamin K1 (phylloquinone) is the plant-based form of vitamin K, crucial for blood coagulation and involved in bone mineralization.
Clinical deficiency is rare in healthy adults thanks to a balanced diet rich in green vegetables.

🟢 What It Does (Strong Evidence)

• Coagulation: proven, essential role — corrects and prevents bleeding disorders due to deficiency.
• Bone health: positively affects certain markers (osteocalcin), especially in low-K diets.
• Physiological synergy: works with vitamin D and calcium for bone metabolism.

🟡 What’s Unclear (Gray Areas)

• Bone / fractures: clinical benefits remain inconsistent in general populations.
• Cardiovascular: potential role through MGP proteins in vascular calcification prevention, but insufficient evidence.
• Preventive supplementation: limited value without deficiency.

🔴 What It Doesn’t Do

• Does not thin the blood — it supports normal coagulation.
• Does not replace medical treatments (anticoagulants, vitamin K2 supplements).
• No proven effect on longevity or athletic performance.

Intake & Dosage (Non-prescriptive)

• Recommended intake (adults): approximately 90–120 µg/day depending on age and sex.
• Supplementation: rarely necessary if diet includes leafy greens.
• Best taken with: a fat-containing meal (fat-soluble vitamin).

💣 Upper Limit (UL)

Note: $No adverse effects reported even at high dietary intakes; caution only in individuals on anticoagulant therapy.
For individuals on vitamin K antagonists, consistent intake is critical to maintain INR stability.
Avoid sudden changes in dietary intake or supplementation without medical guidance.

Safety

• Excellent tolerance at dietary levels.
• Caution only for oral anticoagulant users (warfarin, acenocoumarol).
• Pregnancy/breastfeeding: needs met through normal diet.

Risks & Interactions

• Supplementation unnecessary with a varied diet; over-supplementation not justified.
• Can interfere with vitamin K antagonist therapy (warfarin/acenocoumarol) if intake fluctuates.
• 🚫 Vitamin K antagonists (warfarin, acenocoumarol): any change in K intake (food or supplement) requires medical monitoring (INR).
• Absorption improved when taken with fat-containing meals (fat-soluble vitamin).

Quality Tips

• Prioritize dietary sources (leafy greens).
• For supplements, check form (phylloquinone), dose (µg), and take with a meal containing fats.
• Do not confuse with vitamin K2 (menaquinones).

Sources

• ODS/NIH — Vitamin K Fact Sheet
• EFSA / Health Canada — Nutrient Reference Values