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Original Research Communication |
1 From the Division of Human Nutrition and Epidemiology, Wageningen University, Wageningen, Netherlands; the Nutrition Research and Development Centre, Bogor, Indonesia; the Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago; the Leiden Institute of Chemistry, Leiden University, Leiden, Netherlands; and the Department of Gastroenterology, University Medical Center, St Radboud, Nijmegen, Netherlands.
Background: More information on the bioefficacy of carotenoids in foods ingested by humans is needed.
Objective: We aimed to measure the time required for isotopic enrichment of ß-carotene and retinol in serum to reach a plateau, the extent of conversion of ß-carotene dissolved in oil with use of ß-carotene and retinol specifically labeled with 10 13C atoms, and the intraindividual variation in response.
Design: Indonesian children aged 811 y (n = 35) consumed 2 capsules/d, 7 d/wk, for
10 wk. Each capsule contained 80 µg [12,13,14,15,20,12',13',14',15',20'-13C10]ß-carotene and 80 µg [8,9,10,11,12,13,14,15,19,20-13C10]retinyl palmitate. Three blood samples were drawn per child over a period of
10 wk. HPLC coupled with atmospheric pressure chemical ionization liquid chromatographymass spectrometry was used to measure the isotopic enrichment in serum of retinol with [13C5]retinol and [13C10]retinol and of ß-carotene with [13C10]ß-carotene. The ß-carotene in the capsules used had a cis-trans ratio of 3:1.
Results: Plateau isotopic enrichment was reached by day 21. The amount of ß-carotene in oil required to form 1 µg retinol was 2.4 µg (95% CI: 2.1, 2.7). The amount of all-trans-ß-carotene required to form 1 µg retinol may be lower.
Conclusions: The efficiency of conversion of this ß-carotene in oil was 27% better than that estimated previously (1.0 µg retinol from 3.3 µg ß-carotene with an unknown cis-trans ratio). The method described can be extended to measure the bioefficacy of carotenoids in foods with high precision, requiring fewer subjects than other methods.
Key Words: Bioavailability ß-carotene conversion retinol vitamin A children Indonesia stable isotope carbon isotopes 13C extrinsic labeling LC-MS liquid chromatographymass spectrometry
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