Location: Vegetable Crops ResearchTitle: Maize genotype and food matrix affect the provitamin A carotenoid bioefficacy from staple and carrot-fortified feeds in Mongolian gerbils (Meriones unguiculatus) Author
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2013
Publication Date: 1/8/2014
Publication URL: http://handle.nal.usda.gov/10113/58544
Citation: Schmaelzle, S., Gannon, B., Crawford, S., Arscott, S.A., Goltz, S., Palacios-Rojas, N., Pixley, K.V., Simon, P.W., Tanumihardjo, S.A. 2014. Maize genotype and food matrix affect the provitamin A carotenoid bioefficacy from staple and carrot-fortified feeds in Mongolian gerbils (Meriones unguiculatus). Journal of Agricultural and Food Chemistry. 62(1):136-143. Interpretive Summary: In the last 50 years of crop improvement, nutritional value has been improved for both vegetables, like carrots, and for staple foods, like maize. This process of nutritional improvement, called biofortification, has been applied to increase the orange carotenoid pigment content of carrots and maize. These carotenoids in biofortified carrots and maize serve as sources of vitamin A for consumers, and in previous independent research projects, high carotenoid content carrots and maize have been demonstrated to provide more vitamin A in animal nutrition studies, than their respective low carotenoid counterparts. In our current research, a mixed diet of biofortified maize and carrots was evaluated in animal studies, and it was found that relative to diets containing only carrots, or only maize, less nutritional benefit was observed than the sum of the two vitamin A sources would have predicted. These results suggest that background variables of the food matrix, such as the mixture of plant fibers that come from maize and carrots, may impede the uptake of orange pigments from these foodstuffs during digestion. This research is of interest to nutritionists, dieticians, plant scientists, and international agencies working on global hunger.
Technical Abstract: Biofortification of staple crops to increase provitamin A carotenoids is a promising technique to alleviate vitamin A deficiency. ß-Carotene (ßC) and ß-cryptoxanthin (ßCX) are low in typical maize but higher in biofortified varieties. In vitro screening methods evaluate bioaccessibility of carotenoids from test foods. Two studies were performed with in vitro and in vivo components. Study 1 screened 44 maize genotypes using in vitro analysis; thereafter, seven 50% maize diets assuming a one-to-one equivalency between ßCX and ßC were fed to Mongolian gerbils (Meriones unguiculatus) to assess in vivo bioefficacy. Study 2 assessed provitamin A bioefficacy from 0.5% high-ßC carrots added to 60% staple food diets for 4 wk, followed by in vitro screening of feeds. In study 1, biofortified maize groups showed no difference in liver retinol concentration from each other and all maize groups maintained baseline concentrations (0.235 ± 0.107 'mol/g liver). In study 2, total liver retinol was highest in the potato (0.999 ± 0.276 µmol retinol/liver) and banana groups (0.978 ± 0.197 µmol retinol/liver), while maize (0.666 ± 0.143 µmol retinol/liver) did not differ from baseline (0.702 ± 0.267 µmol retinol/liver). All treatment groups differed from negative control (0.420 ± 0.111 µmol retinol/liver, P <0.0001). Liver a-retinol concentrations differed (P<0.0001) and were highest in the banana group followed by potato, rice, and carrot, which did not differ from each other; maize had the lowest concentration. In conclusion, ßCX and ßC have similar bioefficacy in vivo and matrix effects of staple foods influence provitamin A carotenoid absorption from carrot.