Document Detail

A novel extrinsic reference method for assessing the vitamin A value of plant foods.
MedLine Citation:
PMID:  11522559     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The amounts of vitamin A that are metabolically derived from specific carotene-containing foods are largely unknown. OBJECTIVE: We sought to develop an improved method for estimating the metabolic vitamin A potential of provitamin A carotenoids by using [2H4]retinyl acetate (d4-RA) as an extrinsic reference standard. DESIGN: Healthy subjects consumed a standardized test meal containing 6 mg beta-carotene as either raw carrot or spinach, either 20 or 1 g added fat, and 6.0 micromol d4-RA. Concentrations of unlabeled (d0) retinyl esters (RE), labeled (d4) RE, and carotenoids in the plasma triacylglycerol-rich lipoprotein fraction (d < 1.006 kg/L) were determined in serial blood samples with HPLC and gas chromatography-mass spectrometry. Baseline-corrected areas under the curve for d0-RE, d4-RE, and carotenoids were calculated, and the masses of absorbed d0-retinol and carotenes were estimated assuming 80% absorption of the d4-RA reference dose. RESULTS: In trials with ample (20 g) fat (n = 6), 7 +/- 4% of the 6 mg beta-carotene ingested was taken up as beta-carotene plus RE with 0.3 +/- 0.1 mg as retinol. Test meals without carotenes yielded no beta-carotene or d0-RE response and there was no effect of treatment (either fat amount or vegetable, n = 6) on the mean d4-RE area under the curve. The lower-than-expected vitamin A yields were attributed to poor intestinal uptake rather than to low conversion of beta-carotene to RE. CONCLUSION: The triacylglycerol-rich lipoprotein and d4-RA method, which controls for variation in chylomicron kinetics in vivo and RE recovery during analysis, is useful for obtaining quantitative estimates of the vitamin A potential of single meals.
A J Edwards; C S You; J E Swanson; R S Parker
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  The American journal of clinical nutrition     Volume:  74     ISSN:  0002-9165     ISO Abbreviation:  Am. J. Clin. Nutr.     Publication Date:  2001 Sep 
Date Detail:
Created Date:  2001-08-27     Completed Date:  2001-09-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0376027     Medline TA:  Am J Clin Nutr     Country:  United States    
Other Details:
Languages:  eng     Pagination:  348-55     Citation Subset:  AIM; IM    
Division of Nutritional Sciences and the Department of Food Science, Cornell University, Ithaca, NY 14853, USA.
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MeSH Terms
Antioxidants / analysis,  metabolism,  pharmacokinetics
Area Under Curve
Biological Availability
Chromatography, High Pressure Liquid
Daucus carota / chemistry
Gas Chromatography-Mass Spectrometry
Intestinal Absorption
Isotope Labeling
Nutritive Value
Plants, Edible / chemistry*
Reference Standards
Spinacia oleracea / chemistry
Triglycerides / blood,  chemistry
Vitamin A / analogs & derivatives,  analysis,  metabolism,  pharmacokinetics*
beta Carotene / analysis,  metabolism,  pharmacokinetics*
Reg. No./Substance:
0/Antioxidants; 0/Triglycerides; 11103-57-4/Vitamin A; 127-47-9/retinol acetate; 7235-40-7/beta Carotene

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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