ARS | Publication request: Biofortified Carrot Intake Enhances Liver Antioxidant Capacity and Vitamin A Status in Mongolian Gerbils

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 9, 2008
Publication Date: September 1, 2008
Citation: Mills, J.P., Simon, P.W., Tanumihardjo, S.A. 2008. Biofortified Carrot Intake Enhances Liver Antioxidant Capacity and Vitamin A Status in Mongolian Gerbils. Journal of Nutrition. 138(9):1692-1698.

Interpretive Summary: While orange carrots are what we commonly consume today, purple, red and white carrots have also been introduced for production in the last 15 years. The orange and red pigments are carotneoids, while purple is due to anthocyanins, and all of these pigments have high antioxidant values, based upon chemical measures. Many of these colors can be combined in the same carrot, and carrots with none of the pigments are white. The orange carotenoids also provide dietary vitamin A. In this study gerbils were used as experimental animals to measure both the antioxidant and vitamin A values of orange, purple/orange, purple/orange/red, orange/red, and white carrots. Presence of the orange pigments provides dietary vitamin A, regardless of whether other pigments are present, as was expected. All of the pigments provided antioxidant levels, as was also expected. None of the pigments interacted with each other to enhance or reduce any nutritional values, and white carrots had no vitamin A value and less antioxidant values than pigmented carrots. This was one of the first demonstrations measuring antioxidant levels in a biological system, and values were comparable to chemical estimates. This research is of interest to nutritionists, plant breeders, and consumers interested in the health value of natural pigments in food.

Technical Abstract: Biofortification efforts have increased concentrations of bioactive compounds in carrots. Vitamin A bioefficacy and antioxidant potential of four biofortified carrot varieties [purple/orange (PO), purple/orange/red (POR), orange/red (OR) and orange (O)] were measured in Mongolian gerbils (n = 73). Following a 4-wk vitamin A depletion period and baseline kill (n = 7), freeze-dried carrot powders were mixed into purified feeds and fed to 6 groups (n = 11/group) for 4 wk. White carrot-fed control and vitamin A-supplemented groups were used to calculate carrot provitamin A bioefficacy. Antioxidant capacities of carrot powders, sera, and livers were determined using the 2, 2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation decolorization assay, while carotenoid and retinol concentrations were determined by HPLC. Liver retinol stores in the colored carrot-fed groups (0.62 + 0.13 to 0.67 + 0.08 'mol retinol/liver) did not differ, and were significantly higher than the white carrot-fed control group (0.32 + 0.08 'mol retinol/g) (P < 0.0001). Antioxidant capacity of liver extracts from the four colored carrot-fed groups (10.1 + 1.2 'mol Trolox equivalent antioxidant capacity (TEAC)/g) was significantly higher than white carrot-fed control and vitamin A supplemented groups (9.3 + 0.9 and 8.8 + 1.4 'mol TEAC/g, respectively) (P < 0.05). Serum retinol and antioxidant capacity were not different among treatment groups. Liver vitamin A stores and antioxidant capacity were higher in gerbils fed colored carrots instead of white carrots. Antioxidant activity is one of several proposed mechanisms by which plant foods, like biofortified carrots, may provide additional health benefits beyond maintenance of vitamin A status.