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Intestinal β-carotene bioconversion in humans is determined by a new single-sample, plasma isotope ratio method and compared with traditional and modified area-under-the-curve methods

Lookup NU author(s): Dr Anthony OxleyORCiD, Professor Georg Lietz



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2018 The vitamin A value (bioefficacy) of provitamin A carotenoids is determined by absorption of the carotenoid (bioavailability) and its subsequent conversion to retinol (bioconversion). Here we show that intestinal bioconversion of β-carotene can be estimated based on analysis of a single plasma sample collected 6 h after subjects ingest a test dose of stable isotope-labeled β-carotene from the ratio of retinyl esters to retinyl esters plus β-carotene. Plasma isotope ratio predictions of bioconversion ranged from 50 to– 93% (mean 76%) for 45 healthy young adults with low vitamin A stores. Results were the same as predictions made by a traditional area-under-the-curve method calculated from 0 to– 8 h or a modified area-under-the-curve method calculated from 0 to– 12 h. The modified method may provide better estimates of bioconversion between 8 and 24 h after ingestion of a carotenoid dose when stable isotopes cannot be used due to cost or logistics. Furthermore, because the plasma isotope ratio method requires only one blood sample and no isolation of triglyceride-rich lipoproteins, its use will facilitate estimation of provitamin A carotenoid bioconversion in human subjects and especially children, in whom repeated blood sampling is not feasible.

Publication metadata

Author(s): Ford JL, Green MH, Green JB, Oxley A, Lietz G

Publication type: Article

Publication status: Published

Journal: Archives of Biochemistry and Biophysics

Year: 2018

Volume: 653

Pages: 121-126

Print publication date: 01/09/2018

Online publication date: 27/06/2018

Acceptance date: 25/06/2018

Date deposited: 01/08/2018

ISSN (print): 0003-9861

ISSN (electronic): 1096-0384

Publisher: Academic Press Inc.


DOI: 10.1016/


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Funder referenceFunder name
BB/G004056/1Biotechnology and Biological Sciences Research Council (BBSRC)