Red carrots contain lycopene in addition to alpha- and beta-carotene. The utility of red carrot as a functional food depends in part on the bioavailability of its constituent carotenoids. Lycopene bioavailability was compared in Mongolian gerbils ( Meriones unguiculatus ) fed freeze-dried red carrot and tomato paste (Study 1, n = 47) and whole food extracts dissolved in cottonseed oil (Study 2, n = 39). Diets and supplements were equalized for lycopene and intakes did not differ. Both studies utilized negative (oil) and positive [purified lycopene (Lyc)] controls.

In Study 1, vitamin A liver stores (0.68 ± 0.13 µmol/liver) of the red carrot group did not differ from baseline (0.63 ± 0.13 µmol/liver) and were greater than those of the tomato paste (0.43 ± 0.12 µmol/liver), Lyc (0.51 ± 0.14 µmol/liver), and control (0.38 ± 0.17 µmol/liver) groups (P < 0.003). A similar pattern was observed in Study 2. In both studies, hepatic lycopene was higher in the tomato paste (82.7 ± 26.7 and 80.7 ± 20.2 nmol/liver) groups compared with red carrot groups (59.3 ± 21.9 and 39.5 ± 14.1 nmol/liver, P < 0.0001).

Hepatic lycopene from tomato paste was higher than Lyc in Study 1, but tomato paste extract and Lyc did not differ in Study 2, when both were dissolved in oil. Red carrot maintains vitamin A status, but constituent ß-carotene may interfere with lycopene bioavailability. These results confirm prior studies in humans on the relative bioavailability of lycopene from red carrots and tomato paste and expand them by suggesting the mechanism and determining vitamin A value.

Source: J.P. Mills, P.W. Simon and S.A. Tanumihardjo, 2007. J Nutr 137(6):1395-400.