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

• Published in: Archives of biochemistry and biophysics Vol. 653; pp. 121 - 126
• Main Authors: Ford, Jennifer Lynn, Green, Michael H., Green, Joanne Balmer, Oxley, Anthony, Lietz, Georg
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2018; Elsevier
• Subjects: Adult; Area Under Curve; Area under the curve; beta Carotene - metabolism; beta-carotene; bioavailability; Biological Availability; Biotransformation; blood sampling; Carotenoid bioconversion; Carotenoid bioefficacy; children; Chromatography, Liquid - methods; esters; Female; Humans; ingestion; Intestinal Mucosa - metabolism; isotope labeling; Isotopes; lipoproteins; Male; prediction; stable isotopes; Tandem Mass Spectrometry - methods; Vitamin A; Vitamin A - blood; Young Adult; young adults; β-Carotene; Vitamin A; Area under the curve; Carotenoid bioconversion; Carotenoid bioefficacy; β-Carotene
• ISSN: 0003-9861; 1096-0384; 1096-0384
• DOI: 10.1016/j.abb.2018.06.015

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.