title: Bioavailability and vitamin A value of carotenes from red palm oil assessed by an extrinsic isotope reference method.
abstract: Red palm oil (RPO) contains high concentrations of beta- and alpha-carotene, and is presumed to possess a higher vitamin A value than other foods. The objective was to determine the metabolic vitamin A and carotene values of refined red palm oil in healthy adult subjects, using a stable isotope reference method. Twelve healthy subjects were administered a small standardised meal containing 10 g RPO (2.4 mg beta-carotene and 1.8 mg alpha-carotene) in a blended juice-based drink also containing 2 mg tetradeuterated retinyl acetate (d4-RA) as a metabolic reference. At baseline and at several times after the test meal, the concentrations of carotenes and of d4- and d0-(unlabelled) retinyl esters, in the plasma chylomicron-rich (d < 1.006) fraction were determined by high high-performance liquid chromatography and gas chromatography mass spectrometry, respectively. The masses of palm oil-derived vitamin A and carotenes absorbed ('yield') were calculated assuming 80% absorption of the d4-RA reference dose. The mean yield of retinol from the RPO was 0.41 mg, ranging from 0.17 mg to 0.86 mg. The mean yields of beta- and alpha-carotene were 0.29 mg and 0.25 mg, respectively, suggesting that beta-carotene was more extensively metabolised than alpha-carotene. Subjects assimilated an average of 23% of the dose of carotenes, as the sum of retinol and unmetabolised carotenes. The vitamin A values of red palm oil obtained under these conditions, a mean of 0.17 mg retinol absorbed per mg beta-carotene consumed (beta-carotene : retinol equivalency of 5.7:1) is higher than that of all other vegetable sources we have evaluated to date.
authors.affiliation: Division of Nutritional Sciences, Cornell University, Ithaca, New York 14853, USA. rsp3@cornall.edu
authors.forename: Cha-Sook
authors.initials: CS
authors.lastname: You
authors.forename: Robert S
authors.initials: RS
authors.lastname: Parker
authors.forename: Joy E
authors.initials: JE
authors.lastname: Swanson
mesh_terms: D000975:Antioxidants / Q000032:analysis / Q000493:pharmacokinetics*; D001682:Biological Availability; D002338:Carotenoids / Q000032:analysis / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007408:Intestinal Absorption; D007553:Isotope Labeling; D008297:Male; D000073878:Palm Oil; D010938:Plant Oils / Q000737:chemistry / Q000378:metabolism*; D014801:Vitamin A / Q000378:metabolism; D019207:beta Carotene / Q000032:analysis / Q000493:pharmacokinetics*
chemical_list: D000975:Antioxidants; D010938:Plant Oils; D019207:beta Carotene; D014801:Vitamin A; D002338:Carotenoids; C041635:alpha-carotene; D000073878:Palm Oil