Plasma lipoproteins as carriers of phylloquinone (vitamin K1) in humans

Abstract

The purpose of this study was to characterize the absorption and transport of phylloquinone (vitamin K1) by plasma lipoproteins. Twenty-six healthy subjects (11 men and 15 women) aged 20-78 y received phylloquinone in the amount of either 1.43 or 50 μg/kg body wt orally with a fat-rich meal containing 1.0 g/kg body wt of fat, carbohydrate, and protein and 7.0 mg cholesterol/kg body wt. Blood was obtained at baseline (0 h) and 3, 6, 9, and 12 h after the meal for the measurement of plasma lipid and phylloquinone concentrations in plasma and lipoprotein subfractions. In both groups of subjects, triacylglycerol concentrations peaked after 3 h in plasma and in the triacylglycerol-rich lipoprotein fraction, composed of chylomicrons and VLDLs. Plasma phylloquinone concentrations peaked at 6 h. At baseline and during the postprandial phase, > 53% of plasma phylloquinone was carried by the triacylglycerol-rich lipoprotein fraction. In 9 of the 11 subjects supplemented with 50 μg phylloquinone/kg, plasma lipoproteins were isolated by sequential ultracentrifugation. In these subjects the fraction of plasma phylloquinone carried by LDLs and by HDLs increased progressively from 3% and 4% at 3 h to 14% and 11% at 12 h, respectively. Our data indicate that whereas triacylglycerol-rich lipoproteins are the major carriers of phylloquinone, LDL and HDL may carry small fractions of this vitamin.