HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lin, Y. Articles by Clifford, A. J Search for Related Content PubMed PubMed Citation Articles by Lin, Y. Articles by Clifford, A. J Agricola Articles by Lin, Y. Articles by Clifford, A. J

Variability of the conversion of ß-carotene to vitamin A in women measured by using a double-tracer study design^1,2,3

¹ From the Department of Nutrition, University of California, Davis, and the Western Human Nutrition Research Center, Agricultural Research Service/Pacific West Area, US Department of Agriculture, Davis, CA.

Background: Blood ß-carotene and vitamin A responses to oral ß-carotene are variable in humans. Some individuals are characterized as responders and others as low- or nonresponders. A better understanding of the conditions that produce the variability is important to help design public health programs that ensure vitamin A sufficiency.

Objective: Our objective was to assess variability in absorption and conversion of ß-carotene to vitamin A in vivo in humans by using a novel double-tracer [hexadeuterated (D₆) ß-carotene and D₆ retinyl acetate] approach.

Design: Eleven healthy women were housed at the US Department of Agriculture Western Human Nutrition Research Center metabolic unit for 44 d, where they consumed diets adequate in vitamins and minerals except for carotenoids. After an adaptation period, the women were given 30 µmol D₆ retinyl acetate orally, followed 1 wk later with 37 µmol D₆ ß-carotene (approximately equimolar doses). Time-dependent plasma concentration curves were determined for D₆ retinol, D₆ ß-carotene, and trideuterated (D₃) retinol (derived from D₆ ß-carotene).

Results: Mean (±SE) absorption of D₆ ß-carotene was 3.3 ± 1.3% for all subjects. The mean conversion ratio was 0.81 ± 0.34 mol D₃ retinol to 1 mol D₆ ß-carotene for all subjects. However, only 6 of the 11 subjects had plasma D₆ ß-carotene and D₃ retinol concentrations that we could measure. The mean absorption of D₆ ß-carotene in these 6 subjects was 6.1 ± 0.02% and their conversion ratio was 1.47 ± 0.49 mol D₃ retinol to 1 mol D₆ ß-carotene. The remaining 5 subjects were low responders with 0.01% absorption and a mean conversion ratio of 0.014 ± 0.004 mol D₃ retinol to 1 mol D₆ ß-carotene.

Conclusion: Variable absorption and conversion of ß-carotene to vitamin A both contribute to the variable response to consumption of ß-carotene. Our double-tracer approach is adaptable for identifying efficient converters of carotenoid to retinoid.

Key Words: Carotene • vitamin A • ß-carotene • absorption • metabolism • stable isotope • tracer • women

This article has been cited by other articles:

				R. M. Clark, K. L. Herron, D. Waters, and M. L. Fernandez Hypo- and Hyperresponse to Egg Cholesterol Predicts Plasma Lutein and {beta}-Carotene Concentrations in Men and Women J. Nutr., March 1, 2006; 136(3): 601 - 607. [Abstract] [Full Text] [PDF]

				J. A. Novotny, A. C. Kurilich, S. J. Britz, and B. A. Clevidence Plasma appearance of labeled {beta}-carotene, lutein, and retinol in humans after consumption of isotopically labeled kale J. Lipid Res., September 1, 2005; 46(9): 1896 - 1903. [Abstract] [Full Text] [PDF]

				E. Reboul, P. Borel, C. Mikail, L. Abou, M. Charbonnier, C. Caris-Veyrat, P. Goupy, H. Portugal, D. Lairon, and M.-J. Amiot Enrichment of Tomato Paste with 6% Tomato Peel Increases Lycopene and {beta}-Carotene Bioavailability in Men J. Nutr., April 1, 2005; 135(4): 790 - 794. [Abstract] [Full Text] [PDF]

				G. Tang, J. Qin, G. G Dolnikowski, and R. M Russell Short-term (intestinal) and long-term (postintestinal) conversion of {beta}-carotene to retinol in adults as assessed by a stable-isotope reference method Am. J. Clinical Nutrition, August 1, 2003; 78(2): 259 - 266. [Abstract] [Full Text] [PDF]

				M. van Lieshout, C. E West, and R. B van Breemen Isotopic tracer techniques for studying the bioavailability and bioefficacy of dietary carotenoids, particularly {beta}-carotene, in humans: a review Am. J. Clinical Nutrition, January 1, 2003; 77(1): 12 - 28. [Abstract] [Full Text] [PDF]

				S. J Hickenbottom, J. R Follett, Y. Lin, S. R Dueker, B. J Burri, T. R Neidlinger, and A. J Clifford Variability in conversion of {beta}-carotene to vitamin A in men as measured by using a double-tracer study design Am. J. Clinical Nutrition, May 1, 2002; 75(5): 900 - 907. [Abstract] [Full Text] [PDF]

				A. J Edwards, C.-S. You, J. E Swanson, and R. S Parker A novel extrinsic reference method for assessing the vitamin A value of plant foods Am. J. Clinical Nutrition, September 1, 2001; 74(3): 348 - 355. [Abstract] [Full Text]