Vitamin K2
Supplements · Vitamins · Supplement, Typed Supps
Helps steer calcium into your bones instead of your artery walls.
Stage by stage
- Intake (Softgel): Fat-soluble, needing dietary fat for absorption.
- Small intestine (Micelle transport): Absorbed via the same bile-dependent route as other fat-soluble vitamins.
- Bloodstream (Bound to lipoproteins): Circulates bound to lipoproteins alongside other fat-soluble vitamins.
- Bone & blood vessels (Activates key proteins): Helps direct calcium into bones and away from artery walls.
What the evidence supports
- Supporting normal blood clotting — strong evidence. The original and undisputed role of vitamin K — this is why newborns are given it.
- Improving bone mineral density — limited evidence. Japanese trials using pharmacological MK-4 doses showed fracture reduction; results outside that setting and at supplement doses have been inconsistent.
- Reducing arterial calcification — limited evidence. The mechanism is real and well characterised. Whether supplementing changes clinical outcomes in people who are not deficient is still open.
- Being necessary alongside vitamin D to prevent calcium going to arteries — limited evidence. A popular pairing claim that outruns its evidence. Plausible mechanism, not yet demonstrated outcomes.
Typical dose
90–180 mcg daily of MK-7 in supplements
Upper limit: No upper limit set — no toxicity established from food or supplements
Timing
Often paired with vitamin D, which regulates calcium absorption.
Time to effect
- Weeks–mo: Effects build with consistent use.
Medication interactions
- Warfarin: Vitamin K directly opposes how warfarin works. Even a steady supplement changes your INR — never start or stop it without telling the clinician managing your dose. (high)
Common myth
“K2 is the same as K1.” In reality: K1 (leafy greens) mainly supports clotting; K2 is more linked to directing calcium toward bone.
Food sources
Relevant movements
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