A stable isotope method for the simultaneous measurement of vitamin [K.sub.1] (phylloquinone) kinetics and absorption

Objectives: To measure uptake and disposal kinetics and absolute absorption of vitamin K, using two stable isotope-labelled forms of vitamin [K.sub.1]. Subjects: Ten subjects (nine women and one man) aged between 22 and 31 years, with a mean (± standard deviation) body mass index of 22.5 ± 2.4 kg/[m...

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Bibliographic Details
Published in:European journal of clinical nutrition 2008-11, Vol.62 (11), p.1273
Main Authors: Jones, K.S, Bluck, L.J.C, Wang, L.Y, Coward, W.A
Format: Article
Language:English
Subjects:
Methods
Nutrition
Physiological aspects
Phytonadione
Product/Service Evaluations
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Summary:Objectives: To measure uptake and disposal kinetics and absolute absorption of vitamin K, using two stable isotope-labelled forms of vitamin [K.sub.1]. Subjects: Ten subjects (nine women and one man) aged between 22 and 31 years, with a mean (± standard deviation) body mass index of 22.5 ± 2.4 kg/[m.sup.2]. Subjects took capsules containing 3 µg of methyl-[sup.13]C vitamin [K.sub.1], three times a day for six days to reach a steady state for plasma vitamin [K.sub.1]. 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 µg of ring-[D.sub.4] vitamin [K.sub.1] to measure absorption. Plasma vitamin [K.sub.1] 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 [K.sub.1] were resolved into two exponentials with half-times of 0.22 (± 0.14) and 2.66 (± 1.69) h. Absorption of oral, deuterated vitamin [K.sub.1] 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 [K.sub.1]. The kinetic parameters determined from the intravenous dose allowed determination of the absolute absorption of vitamin [K.sub.1] from a bolus oral dose. doi:10.1038/sj.ejcn.1602859; published online 1 August 2007 Keywords: vitamin [K.sub.1]; phylloquinone; stable isotope; kinetics; absorption
ISSN:0954-3007