Vitamin K2
Also known as: Menaquinone, MK-7, MK-4
The critical co-factor that directs calcium to bones rather than arteries — essential for anyone taking vitamin D3.
What it is
Vitamin K2 is a fat-soluble vitamin in the menaquinone family, distinct from K1 (found in leafy greens and involved in blood clotting). K2 activates proteins that regulate where calcium is deposited in the body — directing it into bones and teeth while preventing its accumulation in arterial walls. It is rarely obtained in sufficient quantities from Western diets.
How it works
K2 activates two key proteins through gamma-carboxylation: osteocalcin (which binds calcium into bone matrix) and matrix Gla protein or MGP (which prevents arterial calcification). Without adequate K2, calcium absorbed with the help of vitamin D3 may be deposited in soft tissues rather than bone — potentially contributing to arterial stiffness. This is why D3 and K2 are frequently co-formulated.
Clinical dose range
90–200 mcg MK-7/day
MK-7 is the preferred form due to its longer half-life (72 hours vs. ~8 hours for MK-4). Dose for bone and cardiovascular protection: 90–200 mcg/day. Higher doses (360–500 mcg) are used in some bone density research. Always take with a fat-containing meal.
Forms comparison
What to look for on the label
- Specifies MK-7 (not just 'Vitamin K2') on the label
- Uses natural MK-7 from fermented natto or equivalent (rather than synthetic)
- Dose between 90–200 mcg MK-7
- Paired with D3 in most high-quality formulations
Health goals supported
Safety & dosing notes
K2 is contraindicated or requires careful management for anyone taking warfarin (Coumadin) or other vitamin K-sensitive anticoagulants — consult a physician. Generally very well tolerated at supplemental doses. No established UL.
SuppsBuddy scores K2 forms carefully: MK-7 receives the highest ingredient quality score, MK-4 receives an acceptable rating at sufficient dose, and K1 receives a lower score when marketed as K2 equivalent. Co-formulation with D3 earns a positive formulation flag.
Frequently asked questions
What is Vitamin K2?
Vitamin K2 is a fat-soluble vitamin in the menaquinone family, distinct from K1 (found in leafy greens and involved in blood clotting). K2 activates proteins that regulate where calcium is deposited in the body — directing it into bones and teeth while preventing its accumulation in arterial walls. It is rarely obtained in sufficient quantities from Western diets.
How does Vitamin K2 work?
K2 activates two key proteins through gamma-carboxylation: osteocalcin (which binds calcium into bone matrix) and matrix Gla protein or MGP (which prevents arterial calcification). Without adequate K2, calcium absorbed with the help of vitamin D3 may be deposited in soft tissues rather than bone — potentially contributing to arterial stiffness. This is why D3 and K2 are frequently co-formulated.
What is the typical clinical dose range for Vitamin K2?
90–200 mcg MK-7/day. MK-7 is the preferred form due to its longer half-life (72 hours vs. ~8 hours for MK-4). Dose for bone and cardiovascular protection: 90–200 mcg/day. Higher doses (360–500 mcg) are used in some bone density research. Always take with a fat-containing meal.
What forms of Vitamin K2 should I look for?
MK-7 (Menaquinone-7): Longest half-life, most studied for bone and cardiovascular outcomes; often derived from natto | MK-4 (Menaquinone-4): Shorter half-life requires multiple daily doses; used in Japanese clinical trials at high doses | K1 (Phylloquinone): Different biological function (blood clotting); does not activate osteocalcin or MGP to the same degree
Is Vitamin K2 safe?
K2 is contraindicated or requires careful management for anyone taking warfarin (Coumadin) or other vitamin K-sensitive anticoagulants — consult a physician. Generally very well tolerated at supplemental doses. No established UL. This information is educational and is not medical advice.
How does SuppsBuddy evaluate Vitamin K2?
SuppsBuddy scores K2 forms carefully: MK-7 receives the highest ingredient quality score, MK-4 receives an acceptable rating at sufficient dose, and K1 receives a lower score when marketed as K2 equivalent. Co-formulation with D3 earns a positive formulation flag.
Related ingredients
This page is for educational purposes only. These statements have not been evaluated by the FDA. This information is not intended to diagnose, treat, cure, or prevent any disease. Always consult a qualified healthcare professional before starting any supplement.