British Journal of Nutrition
- British Journal of Nutrition / Volume 103 / Issue 11 / June 2010, pp 1594-1601
- Copyright © The Authors 2010
- DOI: http://dx.doi.org/10.1017/S0007114509993588 (About DOI), Published online: 23 April 2010
Full Papers
Small quantities of carotenoid-rich tropical green leafy vegetables indigenous to Africa maintain vitamin A status in Mongolian gerbils (Meriones unguiculatus)
|
|
Abstract
Leafy vegetables are important sources of provitamin A carotenoids. Information on their ability to provide vitamin A is often misleading because of the methodology used to assess bioefficacy. Mongolian gerbils were used to evaluate the bioefficacy of provitamin A carotenoids in tropical leafy vegetables (i.e. Solanum nigrum, Moringa oleifera, Vernonia calvoana and Hibiscus cannabinus) that are indigenous to Africa. Gerbils (n 67) were vitamin A-depleted for 5 weeks. After a baseline kill (n 7), the gerbils were weight-matched and assigned to six treatment groups (n 10; four vegetable groups; negative and positive controls). For 4 weeks, the treatments included 35 nmol vitamin A (theoretical concentrations based on 100 % bioefficacy) in the form of vegetables or retinyl acetate. In addition to their diets, the control and vegetable groups received daily doses of oil, while the vitamin A group received retinyl acetate in oil matched to prior day intake. Serum and livers were analysed for vitamin A using HPLC. Serum retinol concentrations did not differ among groups, but total liver vitamin A of the vitamin A and vegetable groups were higher than that of the negative control group (P < 0·0001). Liver β-carotene 15,15′-monooxygenase-1 expression levels were determined for two vegetable groups and were similar to the positive and negative controls. Conversion factors for the different leafy vegetables were between 1·9 and 2·3 μg β-carotene equivalents to 1 μg retinol. Small quantities of these vegetables maintained vitamin A status in gerbils through efficient bioconversion of β-carotene to retinol.
(Received May 08 2009)
(Revised November 23 2009)
(Accepted November 26 2009)
(Online publication April 23 2010)
Key Words:Tropical leafy vegetables; Vitamin A status; Provitamin A carotenoids; Bioconversion factors; Bioefficacy
Correspondence:
c1 Corresponding author: Sherry A. Tanumihardjo, fax +1 608 262 5860, email sherry@nutrisci.wisc.edu
Footnotes
Abbreviations: BCMO1, β-carotene 15,15′-monooxygenase-1
