title: The effect of food preparation on the bioavailability of carotenoids from carrots using intrinsic labelling.
abstract: A strategy to reduce the incidence of vitamin A deficiency is to improve precursor bioavailability from meals. Since vitamin A precursors are fat-soluble, we noted that carotenoids are more easily absorbed from food if prepared in such a way that the food matrix containing provitamin A (β-carotene) is sufficiently fat rich. To quantify this effect, we have developed a stable isotope methodology. By regular watering with 2H-labelled water, we were able to produce several kg of intrinsically labelled carrots, with carotenoids labelled to 0.63 % excess 2H. These were divided into 100 g portions and fed to a small group of healthy subjects both raw and stir-fried. To normalise for inter-individual variation in absorption and subsequent metabolism, small quantities of extrinsically 13C-labelled β-carotene and 2H-labelled retinol acetate were also incorporated into the meal. After ingestion of the carrots, blood lipids were monitored for a period of 3 d in order to determine the kinetics of β-carotene and retinol. From kinetic data, it was estimated that the bioavailability of carrot-derived β-carotene compared with pure β-carotene was about 11 % for raw carrots, but 75 % when the carrots were stir-fried. Conversely, there was a slight reduction in the bioconversion to retinol from β-carotene when the latter was derived from the stir-fried meal compared with that from raw carrots. When these two factors are combined, the yield of retinol from the carotene in carrots was found to be enhanced by a factor of 6.5 by stir-frying.
authors.affiliation: MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge CB1 9NL, UK.
authors.forename: Abdollah
authors.initials: A
authors.lastname: Ghavami
authors.affiliation: MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge CB1 9NL, UK.
authors.forename: W Andy
authors.initials: WA
authors.lastname: Coward
authors.affiliation: MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn Road, Cambridge CB1 9NL, UK.
authors.forename: Les J C
authors.initials: LJ
authors.lastname: Bluck
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000378:metabolism; D001682:Biological Availability; D002247:Carbon Isotopes; D002338:Carotenoids / Q000097:blood / Q000493:pharmacokinetics*; D003296:Cooking; D018552:Daucus carota; D003903:Deuterium; D004224:Diterpenes; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009753:Nutritive Value; D015203:Reproducibility of Results; D012176:Retinoids / Q000097:blood / Q000493:pharmacokinetics; D000084562:Retinyl Esters; D013997:Time Factors; D014801:Vitamin A / Q000031:analogs & derivatives / Q000378:metabolism; D014802:Vitamin A Deficiency / Q000517:prevention & control; D019207:beta Carotene / Q000378:metabolism
chemical_list: D000975:Antioxidants; D002247:Carbon Isotopes; D004224:Diterpenes; D012176:Retinoids; D000084562:Retinyl Esters; D019207:beta Carotene; D014801:Vitamin A; D002338:Carotenoids; C009166:retinol acetate; D003903:Deuterium