Original Article
European Journal of Clinical Nutrition (2008) 62, 1273–1281; doi:10.1038/sj.ejcn.1602859; published online 1 August 2007
A stable isotope method for the simultaneous measurement of vitamin K1 (phylloquinone) kinetics and absorption
Contributors: KSJ, LJCB and WAC designed the study. KSJ was responsible for implementation, volunteer recruitment, sample collection and isotope ratio analysis. LYW performed the HPLC analysis. KSJ wrote the manuscript with LJCB and WAC.
K S Jones1, L J C Bluck1, L Y Wang1 and W A Coward1
1MRC Human Nutrition Research, Elsie Widdowson Laboratory, Cambridge, UK
Correspondence: Dr KS Jones, MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge CB1 9NL, UK. E-mail: kerry.jones@mrc-hnr.cam.ac.uk
Received 16 October 2006; Revised 21 May 2007; Accepted 13 June 2007; Published online 1 August 2007.
Abstract
Objectives:
To measure uptake and disposal kinetics and absolute absorption of vitamin K1 using two stable isotope-labelled forms of vitamin K1.
Subjects:
Ten subjects (nine women and one man) aged between 22 and 31 years, with a mean (
standard deviation) body mass index of 22.52.4 kg/m2. Subjects took capsules containing 3 
g of methyl-13C vitamin K1, three times a day for six days to reach a steady state for plasma vitamin K1 isotopic enrichment. On day seven, subjects were given an intravenous dose of Konakion MM to measure disposal kinetics and at the same time, a capsule containing 4 g of ring-D4 vitamin K1 to measure absorption. Plasma vitamin K1 concentration was measured by high-performance liquid chromatography and isotopic composition by gas chromatography mass spectrometry.
Results:
The disposal kinetics of the intravenous dose of vitamin K1 were resolved into two exponentials with half-times of 0.22 (0.14) and 2.66 (1.69) h. Absorption of oral, deuterated vitamin K1 was 13 (9) %.
Conclusions:
Two-compartmental kinetic parameters observed in this study are similar to those obtained previously using radioactive tracers, but there may be additional slow-turnover body pools acting as stores of vitamin K1. The kinetic parameters determined from the intravenous dose allowed determination of the absolute absorption of vitamin K1 from a bolus oral dose.
Keywords:
vitamin K1, phylloquinone, stable isotope, kinetics, absorption
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