Vitamin A equivalency of beta-carotene in healthy adults: limitation of the extrinsic dual-isotope dilution technique to measure matrix effect.
Data on the vitamin A equivalency of beta-carotene in food are inconsistent. We quantified the vitamin A equivalency (microg) of beta-carotene in two diets using the dual-isotope dilution technique and the oral-faecal balance technique. A diet-controlled, cross-over intervention study was conducted in twenty-four healthy adults. Each subject followed two diets for 3 weeks each: a diet containing vegetables low in beta-carotene with supplemental beta-carotene in salad dressing oil ('oil diet') and a diet containing vegetables and fruits high in beta-carotene ('mixed diet'). During all 6 weeks, each subject daily consumed a mean of 55 (sd 0.5) microg [13C10]beta-carotene and 55 (sd 0.5) microg [13C10]retinyl palmitate in oil capsules. The vitamin A equivalency of beta-carotene was calculated as the dose-corrected ratio of [13C5]retinol to [13C10]retinol in serum and from apparent absorption by oral-faecal balance. Isotopic data quantified a vitamin A equivalency of [13C10]beta-carotene in oil of 3.4 microg (95 % CI 2.8, 3.9), thus the bio-efficacy of the beta-carotene in oil was 28 % in the presence of both diets. However, data from oral-faecal balance estimated vitamin A equivalency as 6:1 microg (95 % CI 4, 7) for beta-carotene in the 'oil diet'. beta-Carotene in the 'oil diet' had 2.9-fold higher vitamin A equivalency than beta-carotene in the 'mixed diet'. In conclusion, this extrinsic labelling technique cannot measure effects of mixed vegetables and fruits matrices, but can measure precisely the vitamin A equivalency of the beta-carotene in oil capsules.
Van Loo-Bouwman
Carolien A
CA
Department of Gastroenterology and Hepatology, Radboud University Nijmegen Medical Centre, Geert Grooteplein 8, PO Box 9101, 6500 HB Nijmegen, The Netherlands. VanLooBouwman@hotmail.com
West
Clive E
CE
van Breemen
Richard B
RB
Zhu
Dongwei
D
Siebelink
Els
E
Versloot
Pieter
P
Hulshof
Paul J M
PJ
van Lieshout
Machteld
M
Russel
Frans G M
FG
Schaafsma
Gertjan
G
Naber
Ton H J
TH
D000328:Adult; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D002214:Capsules; D002247:Carbon Isotopes / Q000494:pharmacology; D018592:Cross-Over Studies; D004032:Diet; D004042:Dietary Fats, Unsaturated; D019587:Dietary Supplements; D002149:Energy Intake; D005243:Feces / Q000737:chemistry; D005260:Female; D005638:Fruit; D006801:Humans; D007201:Indicator Dilution Techniques; D007553:Isotope Labeling; D008297:Male; D013810:Therapeutic Equivalency; D014675:Vegetables; D014801:Vitamin A / Q000032:analysis / Q000097:blood*; D055815:Young Adult; D019207:beta Carotene / Q000032:analysis / Q000097:blood / Q000494:pharmacology*
D015415:Biomarkers; D002214:Capsules; D002247:Carbon Isotopes; D004042:Dietary Fats, Unsaturated; D019207:beta Carotene; D014801:Vitamin A