Lycopene uptake and tissue disposition in male and female rats

Epidemiologic and clinical studies suggest that tomato consumption may reduce the risk of cancer. Lycopene, a hydrocarbon carotenoid, is the major carotenoid in tomatoes and, as a potent singlet oxygen quencher, has been considered by some to be the biologically active agent responsible for the reduction of cancer risk associated with tomato consumption. However, little is known concerning lycopene absorption or biological activity in rodent models of cancer. Therefore, the present study was designed to provide information regarding the uptake and tissue disposition of lycopene and related carotenoid after feeding a diet containing a carotenoid mixture extracted from tomatoes (Betatene). Betatene was added to the diet at 2.3, 0.9, 0.45, 0.23, 0.09 and 0 (mM/kg diet) and fed to male and female Fischer-344 rats for a period of 10 weeks. Using reverse phase HPLC methods, it was found that approximately 55% of administered lycopene was excreted in the feces. In both males and females, lycopene concentrations were highest in the liver (120-42 microg/g wet wt.); physiologically significant levels were detected in prostate (97-47 ng/g), lung (227-134 ng/g), mammary gland (309-174 ng/g) and serum (285-160 ng/ml). Tissue concentrations were related to dose with the exception of serum, and differences between males and females were minimal. Other carotenoids present in Betatene (i.e., phytoene, phytofluene, z-carotene and beta-carotene) were also absorbed and stored in the liver. These results indicate that lycopene, when incorporated into the semipurified AIN-76A diet, is absorbed in both male and female rats in a dose-related manner and can be detected at nanogram levels in a variety of target organs.