Vitamin K2 (MK-7)

Summary

Vitamin K2 (menaquinone, especially MK-7) works in synergy with vitamin K1 to support coagulation and calcium regulation between bones and blood vessels.
It plays a key role in activating osteocalcin (in bones) and matrix Gla protein (MGP) (in vessels), helping prevent vascular calcification while supporting bone density.

🟢 What It Does (Strong Evidence)

• Activates proteins that direct calcium toward the bones and away from blood vessels.
• Can improve osteocalcin carboxylation, promoting better calcium utilization in bone tissue.
• Acts synergistically with vitamin D3 in calcium metabolism.

🟡 What’s Unclear (Gray Areas)

• Clinical results on bone density and fracture risk are inconsistent (effects modest and variable).
• Evidence for vascular calcification prevention remains preliminary and not confirmed long term.
• The optimal intake and form of K2 are not yet standardized.

🔴 What It Doesn’t Do

• Does not replace vitamin D or calcium — it acts as a cofactor.
• Does not thin the blood; it supports normal clotting.
• No proven effect on longevity or athletic performance.

Intake & Dosage (Non-prescriptive)

• Total recommended intake (K1 + K2): ≈ 90–120 µg/day (depending on age and sex).
• Supplemental MK-7 range: 45–180 µg/day, commonly 90–120 µg/day in studies.
• Take with a fat-containing meal (fat-soluble vitamin).

💣 Upper Limit (UL)

Note: $No known toxicity at dietary levels; caution only for those taking vitamin K antagonist anticoagulants.
For those on vitamin K antagonists, any dietary change or supplement use requires close INR monitoring.
Avoid abrupt changes in dietary vitamin K or supplementation without medical supervision.

Safety

• Very well tolerated at standard doses.
• Caution advised with oral anticoagulant therapy.
• No safety concerns at nutritional doses (≤200 µg/day).

Risks & Interactions

• May interact with certain anticoagulants (vitamin K antagonists).
• At high, prolonged intakes: caution in individuals with clotting disorders.
• 🚫 Vitamin K antagonists (warfarin, acenocoumarol): medical adjustment required — do not supplement without supervision.
• Absorption improves when taken with a meal containing fat.

Quality Tips

• Choose a natural MK-7 form (derived from natto).
• Verify purity and dose per capsule (µg).
• Combine with vitamin D3 for synergistic effects on bone health.

Food Sources

• K1: green vegetables (kale, broccoli, spinach).
• K2 (MK-7): natto (fermented soy), aged cheeses, and some animal products (egg yolk, liver).

Sources

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