Nutritional Intake of Vitamins K1 (Phylloquinone) and K2 (Menaquinone) in The Netherlands

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Abstract
Vitamin K plays a key role in the hepatic synthesis of blood clotting factors. Recently, other tissues (bone, vessel wall) were shown to produce vitamin K-dependent proteins not involved in blood coagulation. Multiple forms of vitamin K have been found in human food: phylloquinone (K1) and various menaquinones. A recommended dietary allowance (RDA) has only been defined for K1, and its value is exclusively based on blood clotting data. We have prepared a provisional table of menaquinones in food, which has been used to calculate the total vitamin K intake in a well-defined cohort of the Dutch population. It is concluded that K1 is the major form of nutritional vitamin K, that total vitamin K intake is higher than in other populations described and that the correlation between vitamin K intake and serum concentration is poor. It is suggested that present RDA values be reconsidered and intakes comparable with those in the highest quartile of our study population are recommended.