The effect of food preparation on the bioavailability of carotenoids from carrots using intrinsic labelling

Br J Nutr. 2012 May;107(9):1350-66. doi: 10.1017/S000711451100451X. Epub 2011 Sep 19.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antioxidants / metabolism
  • Biological Availability
  • Carbon Isotopes
  • Carotenoids / blood
  • Carotenoids / pharmacokinetics*
  • Cooking*
  • Daucus carota*
  • Deuterium
  • Diterpenes
  • Female
  • Humans
  • Male
  • Middle Aged
  • Nutritive Value
  • Reproducibility of Results
  • Retinoids / blood
  • Retinoids / pharmacokinetics
  • Retinyl Esters
  • Time Factors
  • Vitamin A / analogs & derivatives
  • Vitamin A / metabolism
  • Vitamin A Deficiency / prevention & control
  • beta Carotene / metabolism


  • Antioxidants
  • Carbon Isotopes
  • Diterpenes
  • Retinoids
  • Retinyl Esters
  • beta Carotene
  • Vitamin A
  • Carotenoids
  • retinol acetate
  • Deuterium