An LC/MS/MS method for stable isotope dilution studies of β-carotene bioavailability, bioconversion, and vitamin A status in humans
Date
2014
Authors
Oxley, A.
Berry, P.
Taylor, G.
Cowell, J.
Hall, M.J.
Hesketh, J.
Lietz, G.
Boddy, A.V.
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Journal article
Citation
Journal of Lipid Research, 2014; 55(2):319-328
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Abstract
Isotope dilution is currently the most accurate technique in humans to determine vitamin A status and bioavailability/bioconversion of provitamin A carotenoids such as beta-carotene. However, limits of MS detection, coupled with extensive isolation procedures, have hindered investigations of physiologically-relevant doses of stable isotopes in large intervention trials. Here, a sensitive liquid chromatography-tandem mass spectrometry (LC/MS/MS) analytical method was developed to study the plasma response from coadministered oral doses of 2 mg [C-13(10)]beta-carotene and 1 mg [C-13(10)]retinyl acetate in human subjects over a 2 week period.
A reverse phase C-18 column and binary mobile phase solvent system separated beta-carotene, retinol, retinyl acetate, retinyl linoleate, retinyl palmitate/retinyl oleate, and retinyl stearate within a 7 min run time. Selected reaction monitoring of analytes was performed under atmospheric pressure chemical ionization in positive mode at m/z 537 -> 321 and m/z 269 -> 93 for respective [C-12]beta-carotene and [C-12]retinoids; m/z 547 -> 330 and m/z 274 -> 98 for [C-13(10)]beta-carotene and [C-13(5)] cleavage products; and m/z 279 -> 100 for metabolites of [C-13(10)]retinyl acetate.
A single one-phase solvent extraction, with no saponification or purification steps, left retinyl esters intact for determination of intestinally-derived retinol in chylomicrons versus retinol from the liver bound to retinol binding protein. Coadministration of [C-13(10)]retinyl acetate with [C-13(10)]beta-carotene not only acts as a reference dose for inter-individual variations in absorption and chylomicron clearance rates, but also allows for simultaneous determination of an individual's vitamin A status.
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Data source: Supplemental data, https://doi.org/10.1194/jlr.D040204
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Copyright 2014 American Society for Biochemistry and Molecular Biology (https://creativecommons.org/licenses/by/4.0/)
Access Condition Notes: This is an open access article