Vitamin K2
Vitamin K2
Snapshot
Vitamin K2 is a fat‑soluble vitamin crucial for activating proteins that regulate calcium metabolism, supporting bone mineralization, vascular health, and proper blood clotting.
What is Vitamin K2 (Menaquinone)?
Vitamin K2 refers to the menaquinone family of compounds (MK‑4 through MK‑13), distinguished by varying isoprenoid side‑chain lengths. Unlike vitamin K1 (phylloquinone), K2 forms are produced by gut bacteria and found in fermented foods, with superior tissue distribution.
Where It Comes From
Dietary vitamin K2 is sourced from fermented foods such as natto (rich in MK‑7), aged cheeses, and animal products like liver and egg yolks (notably MK‑4). Supplements provide synthetic or fermentation‑derived MK‑4 or MK‑7 forms in oil‑based capsules.
Key Nutrients & Compounds
Provides menaquinones (MK‑4 commonly at 1–5 mg doses, MK‑7 at 100–200 µg) that serve as cofactors for γ‑glutamyl carboxylase, converting osteocalcin and matrix Gla protein into their active, calcium‑binding forms.
Health Benefits
Vitamin K2 activates osteocalcin, facilitating calcium incorporation into bone matrix and enhancing bone strength; activates matrix Gla protein, inhibiting arterial calcification and supporting cardiovascular health; and contributes to normal coagulation via activation of clotting factors II, VII, IX, and X.
Recommended Dosage
No official RDA exists for K2 specifically. Clinical studies use 45–180 µg/day of MK‑7 or 1–5 mg/day of MK‑4. A common supplemental regimen is 100 µg of MK‑7 daily alongside vitamin D to synergize calcium metabolism.
How to Use It
Take Vitamin K2 (MK‑7 or MK‑4) supplements with a meal containing dietary fat to optimize absorption. For combined bone support, pair with vitamin D3 and calcium. Maintain consistent daily dosing to sustain active Gla‑protein levels.
Who Should Use It?
Individuals at risk for osteoporosis, those with low dietary vitamin K intake, postmenopausal women, and anyone seeking to support healthy calcium balance and vascular integrity may benefit. Consult a healthcare provider if on anticoagulant therapy.
Possible Interactions or Cautions
Vitamin K2 may reduce the effectiveness of vitamin K–antagonist anticoagulants (e.g., warfarin); monitor INR and adjust medication under medical supervision. High doses are generally well tolerated, with no known toxicity.
Final Thoughts
Vitamin K2 is a key modulator of calcium utilization, directing it toward bone and away from arteries. When combined with vitamin D and calcium, it offers synergistic support for skeletal and cardiovascular health in a balanced supplementation strategy.
Scientific Studies
Knapen MHJ, et al. Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women: a double-blind randomised clinical trial. Thromb Haemost. 2015;113(5):1135–1144. https://doi.org/10.1160/TH14-11-0938
Ikeda Y, et al. Effect of oral administration of vitamin K2 (menatetrenone) on bone metabolism and bone mass in osteoporosis. Bone. 1997;20(5):431–436. https://doi.org/10.1016/S8756-3282(97)00041-0
Schurgers LJ, Vermeer C. Differential lipoprotein transport pathways of K-vitamers in healthy subjects. Biochim Biophys Acta. 2002;1570(1):27–32. https://doi.org/10.1016/S0005-2760(02)00112-1