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Home / Evidence / Vitamin K2
Vitamin and bone metabolism

Vitamin K2

Biologically relevant to clotting and bone proteins; routine anti-calcification claims exceed the trial evidence.

The 30-second verdict Vitamin K is essential for activation of proteins involved in blood clotting and bone metabolism. K2 forms are heavily marketed alongside vitamin D for bone and arterial health, but trials have not established a universal need for K2 supplementation or a reliable reduction in cardiovascular events, fractures or mortality in generally healthy adults.

Evidence matrix

These scores describe different evidence domains. A strong mechanism cannot compensate for missing human outcomes, and a useful clinical effect need not imply slower biological ageing.

Human clinical outcomes Preliminary
Human biomarkers Moderate
Animal lifespan None
Mechanistic plausibility Strong
Safety certainty Moderate
Direct longevity relevance Preliminary

What has been shown in humans?

Human studies measure vitamin K status, carboxylation markers, bone density and vascular endpoints with mixed results. Benefits may depend on baseline intake, formulation, dose and population. A favourable biomarker change is not equivalent to fewer fractures or cardiovascular events.

What remains uncertain?

The clinical importance of common vitamin K biomarkers, comparative value of MK-4 and MK-7, and which groups benefit beyond dietary adequacy remain uncertain.

Doses used in research

Descriptive, not prescriptive Trials use different K2 forms and doses that are not directly interchangeable. Warfarin users require stable vitamin K intake and professional advice rather than self-directed dose changes.

Safety and interpretation

  • Vitamin K can materially affect warfarin and related vitamin K antagonist treatment.
  • People using anticoagulants should not start, stop or change vitamin K supplements without clinical guidance.
  • Claims that K2 automatically prevents vitamin D from causing arterial calcification are not established by clinical outcome trials.

Primary sources and evidence reviews

Editorial note

This dossier was last reviewed on 13 July 2026. Ratings can change when larger trials, adverse-event data or better systematic reviews appear. Corrections should alter the page rather than being buried in a social-media thread.