Biological effects of vitamin K and concentration of vitamin K in Norwegian food.


Drevon CA, Henriksen HB, Sanderud M, Gundersen TE, Blomhoff R.




Tidsskr Nor Laegeforen


BACKGROUND: Vitamin K has several biological effects and dietary intake seems to be more important than previously believed because of low bioavailability of the vitamins from the colon. MATERIALS AND METHODS: Data from the literature were identified on PubMed, and data from NORKOST II (a dietary study from 1997 based on a nation-wide sample of respondents) were used to calculate dietary intake of vitamin K. RESULTS: The dietary intake of vitamin K in Norway seems to be < 50% of what is recommended. The stores of vitamin K are small and T/2 in the body is approximately 1-1.5 day. Vitamin K executes its effects by carboxylation of proteins and as ligand (vitamin K2) for a nuclear transcription factor. Biological effects beyond coagulation include bone formation, neural functioning and blood vessel calcification. Anticoagulation with warfarin inhibits vitamin K-dependent reactions and may have detrimental effects on bone formation. INTERPRETATION: It is possible that the high incidence of osteoporosis in Norway may be due to the low dietary intake of vitamin K, hence it is suggested that the intake of vitamin K should be increased and vitamin K antagonists be replaced with specific thrombin inhibitors. New technology allows measurements of plasma concentration of vitamin K in relation to malabsorption, insufficient diet, and osteoporosis.