Determination of Phylloquinone and Menaquinones in Food

Abstract

Fluctuations in international normalized ratio values are often ascribed to dietary changes in vitamin K intake. Here we present a database with vitamin K<sub>1</sub> and K<sub>2</sub> contents of a wide variety of food items. K<sub>1</sub> was mainly present in green vegetables and plant margarins, K<sub>2</sub> in meat, liver, butter, egg yolk, natto, cheese and curd cheese. To investigate the effect of the food matrix on vitamin K bioavailability, 6 healthy male volunteers consumed either a detergent-solubilized K<sub>1</sub> (3.5 µmol) or a meal consisting 400 g of spinach (3.5 µmol K<sub>1</sub>) and 200 g of natto (3.1 µmol K<sub>2</sub>). The absorption of pure K<sub>1</sub> was faster than that of food-bound K vitamins (serum peak values at 4 h vs. 6 h after ingestion). Moreover, circulating K<sub>2</sub> concentrations after the consumption of natto were about 10 times higher than those of K<sub>1</sub> after eating spinach. It is concluded that the contribution of K<sub>2</sub> vitamins (menaquinones) to the human vitamin K status is presently underestimated, and that their potential interference with oral anticoagulant treatment needs to be investigated.