ARS | Publication request: Serum a- and b-carotene concentrations qualitatively respond to sustained carrot feeding

Submitted to: Experimental Biology and Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 23, 2009
Publication Date: November 1, 2009
Citation: Tanumihardjo, S., Horvitz, M., Dosti, M.P., Simon, P.W. 2009. Serum a- and b-carotene concentrations qualitatively respond to sustained carrot feeding. Experimental Biology and Medicine. 234:1280-1286.

Interpretive Summary: Plant breeders have exerted substantial effort to genetically increase the nutritional content of certain nutrients in certain food crops. In most cases the increase in nutrient content able to be quantified by laboratory measurements have been presumed to increase nutritional value for individuals that consume the improved crop, without actually comparing measures of nutritional value in human subjects consuming both the unimproved and improved versions of the crop. In this study, this comparison was actually made, evaluating high-carotene, dark orange carrots to typical orange carrots, to white carrot that lack carotenes in human nutritional trials where serum carotene content (the best measure to evaluate delivery of this nutrient to consumers of carrots) was evaluated. It was determined that breeding for high carotene content of carrots actually results in carrots that deliver more carotenes to consumers. Carrot carotenes are the largest single dietary source of orange provitamin A carotenes (i.e. orange carotene pigments that are converted to vitamin A when humans and animals consume them) in the U.S. diet. The results of this study confirm that breeding for higher nutritional content of carrots does, in fact, result in a product that delivers more nutrients than typical carrots. This information is important to carrot producers, breeders, and consumers, and also more generally to plant breeders, nutritionists, and consumers.

Technical Abstract: b-Carotene is a predominant source of vitamin A in developing countries. Genetically selected ‘‘high carotene’’ carrots could have an impact on the vitamin A and antioxidant status of people if widely adopted. A 3 3 3 crossover study in humans (n = 10) evaluated the difference in uptake and clearance of a- and bcarotene from carrots genetically selected and traditionally bred to have high, typical, or no carotene. Subjects were fed white (0 mg a- and b-carotene/d), orange (1.8 mg a-carotene and 2.6 mg bcarotene/ d), or dark-orange (4 mg a-carotene and 7 mg bcarotene/ d) carrots in muffins for 11 d, with a 10-d washout phase between treatments. Serum carotenoid and retinol concentrations were measured by HPLC. C-reactive protein (CRP), an indicator of underlying inflammation or infection which may lower serum retinol, was measured at the beginning of each period. A significant treatment effect occurred for serum a- and b-carotene concentrations (P < 0.001), and a trend towards a negative effect of subjects’ BMI on concentrations (P = 0.08). A significant treatment by sequence interaction was observed (P = 0.038), which was attributable to a difference in serum a- and b-carotene concentrations between carrot treatments in the first period. Serum retinol remained stable for the first 20 d of the intervention and then decreased (P = 0.02). CRP was not elevated in any subject. High carotene carrots provide more provitamin A carotenoids than the typical store-bought variety, without a change in flavor. The availability of high carotene carrots could readily increase consumption of b-carotene and potentially impact the vitamin A status of those individuals who are deficient or at risk of depletion.