Requirement
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For
more than half a century vitamin K requirement was defined as the
daily intake required to sustain normal blood coagulation. After
the discovery of its cofactor function for gammaglutamate carboxylase,
vitamin K requirement was also defined as the intake needed for
full clotting factor carboxylation in the liver. Based on the needs
of the liver, the recommended daily intake ranges between 1 and
1.5 micrograms per kg body weight. After the discovery of extra-hepatic
Gla-proteins, it became apparent that these needed higher vitamin
K intakes for full carboxylation, and thus for full activity. Full
osteocalcin carboxylation, for instance, is only achieved at 10-fold
higher intakes. Presently, the need for increasing vitamin K intake
is debated. VitaK's standpoint is that at the present dietary habits,
for the majority of the healthy population a supplemental dose of
50 micrograms of K2 (menaquinone-7) may have significant health
effects.
One exception is formed by patients receiving oral anticoagulant treatment (vitamin K-antagonists including warfarin, acenocoumarol and phenprocoumon): they should never take vitamin supplements without prior discussing this with their medical doctor.
Recommended literature:
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