All-trans β-carotene is absorbed preferentially to 9-cis β-carotene, but the latter accumulates in the tissues of domestic ferrets (Mustela putorius puro)

The algae Dunaliella bardawil and Dunaliella salina naturally contain large concentrations of all-trans and 9-cis beta-carotene (beta C) The purpose of this study was to compare the relative serum and tissue accumulation of all-trans and g-cis beta C in ferrets fed different ratios of all-trans/9-cis beta C derived from two commercial sources, D. bardawil or D. salina (Betatene). Male ferrets (7 wk old) were fed carotene-free, pelleted diets for 27 d. Beginning on d 18, groups of ferrets (n = 6 or 7) received daily, one of six oral supplements varying in ratios of 9-cis and all-trans beta C mixed with similar to 1.0mL of Ensure. Four supplements containing 5.2-8.3 mu mol total beta C were prepared from a 20% Betatene preparation, D. bardawil, a high-cia Betatene preparation, and Betatene further enriched in g-cis beta C with ail-trans beta C/9-cis beta C ratios of 2.2, 1.5, 0.6 and 0.4, respectively. Two control supplements, high and low beta C, were prepared from commercial beta C beadlets. The high control supplement had an all-trans/9-cis ratio of 19.0, whereas g-cis beta C was not detected in the low supplement. On d 27, serum and tissues were obtained for HPLC analysis of beta C and its isomers. Analysis of livers showed that all-trans beta C was the primary isomer present, but 9-cis and other isomers were also detected in ail groups. The hepatic all-trans/9-cia ratios were 5.9, 4.9, 2.5, 1.4, 52.2 and 47.5, respectively, for the groups listed above. Lower amounts of all-trans and 9-cis beta C were found in kidneys compared with the liver, but ratios of all-trans/9-cis were not different among groups. Only trace amounts of 9-cis beta C were found in serum. These results demonstrate that the algae D. bardawil and D. salina provide a bioavailable source of beta C isomers, but, as in humans, absorption of g-cis beta C is poor and any g-cis beta C absorbed is apparently cleared by the liver.