Vitamin A equivalency of β-carotene in healthy adults: limitation of the extrinsic dual-isotope dilution technique to measure matrix effect

• Published in: British journal of nutrition Vol. 101; no. 12; pp. 1837 - 1845
• Main Authors: Van Loo-Bouwman, Carolien A., West, Clive E., van Breemen, Richard B., Zhu, Dongwei, Siebelink, Els, Versloot, Pieter, Hulshof, Paul J. M., van Lieshout, Machteld, Russel, Frans G. M., Schaafsma, Gertjan, Naber, Ton H. J.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.06.2009
• Subjects: Adult; adults; Analysis of Variance; antioxidants; beta Carotene - analysis; beta Carotene - blood; beta Carotene - pharmacology; beta-carotene; Biological and medical sciences; Biomarkers - blood; Capsules; Carbon Isotopes - pharmacology; Cross-Over Studies; Diet; Dietary Fats, Unsaturated; Dietary Supplements; dosage; Energy Intake; Feces - chemistry; Feeding. Feeding behavior; Female; Food matrix; Fruit; fruits (food); Fundamental and applied biological sciences. Psychology; Humans; Indicator Dilution Techniques; Innovative Techniques; Isotope Labeling; Male; nutrient uptake; nutritional adequacy; nutritional intervention; nutritive value; retinyl palmitate; Stable isotopes; Therapeutic Equivalency; Vegetables; Vertebrates: anatomy and physiology, studies on body, several organs or systems; vitamin A; Vitamin A - analysis; Vitamin A - blood; Vitamin A equivalency; vitamin supplements; Young Adult; β-Carotene; Food matrix; Vitamin A equivalency; Stable isotopes; β-Carotene; Human; Carotene; Vitamin; Isotope dilution; Retinol; Vertebrata; Mammalia; Adult; Technique; Isotopes; Food
• ISSN: 0007-1145; 1475-2662; 1475-2662
• DOI: 10.1017/S0007114508131762

Data on the vitamin A equivalency of β-carotene in food are inconsistent. We quantified the vitamin A equivalency (μg) of β-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 β-carotene with supplemental β-carotene in salad dressing oil (‘oil diet’) and a diet containing vegetables and fruits high in β-carotene (‘mixed diet’). During all 6 weeks, each subject daily consumed a mean of 55 (sd 0·5) μg [13C10]β-carotene and 55 (sd 0·5) μg [13C10]retinyl palmitate in oil capsules. The vitamin A equivalency of β-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]β-carotene in oil of 3·4 μg (95 % CI 2·8, 3·9), thus the bio-efficacy of the β-carotene in oil was 28 % in the presence of both diets. However, data from oral–faecal balance estimated vitamin A equivalency as 6:1 μg (95 % CI 4, 7) for β-carotene in the ‘oil diet’. β-Carotene in the ‘oil diet’ had 2·9-fold higher vitamin A equivalency than β-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 β-carotene in oil capsules.