Cis-lycopene is more bioavailable than trans-lycopene in vitro and in vivoin lymph-cannulated ferrets

Lycopene is the predominant carotenoid in tomatoes and tomato-based foods a nd is also a predominant carotenoid in human serum and tissues. Intake of l ycopene-rich foods was recently associated with decreased risk for several chronic diseases. The observation that serum and tissue lycopene is more th an 50% cis-lycopene, whereas tomatoes and tomato-based foods contain mainly all-trans-lycopene, has led to the hypothesis that cis-isomers of lycopene are more bioavailable. We tested this hypothesis both in vitro (study 1) a nd in vivo (study 2). In study 1, bile acid micelles containing crystalline lycopene were prepared. The crystalline lycopene used for these analyses w as 54.4% cis-lycopene. The optically clear micelle preparation contained 75 .9% cis-lycopene in repeated analyses. In study 2, mesenteric lymph duct ca nnulated ferrets were used to study the in vivo absorption of lycopene from Lycored(TM) (an ethyl acetate extract of tomatoes containing 5% lycopene b y weight; of which 91% was all-trans lycopene). Before being anesthetized, male ferrets (n = 7) were dosed orally with 40 mg lycopene per kg body weig ht in soybean oil. Lymph secretions were collected, on ice, for 2 h. The re sidual stomach and small intestinal contents, mucosa lining, lymph secretio n and serum were analyzed by HPLC. Whereas the dose, stomach and intestinal contents contained 6.2-17.5% cis-lycopene, the mesenteric lymph secretions contained significantly more, 77.4%, cis-lycopene (P < 0.01). These studie s demonstrate that in ferrets, cis-isomers of lycopene are more bioavailabl e than trans-lycopene probably because cis-isomers are more soluble in bile acid micelles and may be preferentially incorporated into chylomicrons.