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Simplified approaches for estimating vitamin A stores and β‐carotene bioconversion in humans (39.6)
Author(s) -
Park Hyunjin,
Lietz Georg,
Oxley Anthony,
Boddy Alan,
Berry Phil,
Wyss Adrian,
Schalch Wolfgang,
Green Michael
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.39.6
Subject(s) - bioconversion , chemistry , retinyl acetate , vitamin , chromatography , dilution , retinol , zoology , biochemistry , physics , biology , thermodynamics , fermentation
Better methods are needed to assess vitamin A (VA) status and the efficiency of bioconversion of β‐carotene (BC) to retinol (ROH). Data on plasma ROH kinetics from 2 h to 14 d after an oral tracer dose of [ 13 C 10 ]BC and [ 13 C 10 ]retinyl acetate (RAc) to 33 healthy young adults were analyzed using model‐based compartmental analysis (WinSAAM, the Windows version of the Simulation, Analysis and Modeling software). The 6‐compartment model that fit data for all subjects predicted 5.3 pools of plasma ROH were transferred into extravascular stores each day, with ~17%/d recycling back to plasma; 6.5%/day was irreversibly lost and total body VA stores (TBS) were 146 ± 89 μmol (mean ± SD). We derived a simplified isotope dilution (“Olson”) equation for TBS, eliminating several factors and assumptions: TBS = F * (1 / SA), where F (fraction of dose [FD] absorbed and retained) was estimated as 0.61 from the kinetic data and SA (specific activity) is FD 13 C 10 [ROH] in plasma 3 d after dosing / plasma ROH pool (μmol). TBS calculated using the equation was 149 ± 85 μmol, essentially the same as the value predicted by the model. BC bioconversion, calculated as FD 13 C 5 [ROH] (derived from BC) / 13 C 10 [ROH] (derived from RAc) at 2 d, averaged 23 ± 11% and was significantly correlated (R=0.942) with WinSAAM’s estimate based on areas under the curves (26 ± 12%). Our results indicate that both TBS and BC conversion to ROH can be estimated based on blood samples taken 3 and 2 d, respectively, after dosing. With further refinement, one sample at 3 d may suffice. Grant Funding Source : BBSRC, U.K. and DSM, Basel, Switzerland