-Isomers of Astaxanthin Exhibit Greater Bioavailability and Tissue Accumulation Efficiency than the All--Isomer.

The purpose of the present study was to clarify the differences in the bioavailability and tissue accumulation efficiency between (all-)- and ()-astaxanthin. Astaxanthin with a high proportion of the -isomer (especially rich in the 9- and 13-isomers) was prepared from (all-)-astaxanthin by thermal treatment and solid-liquid separation. The all--isomer- or -isomer-rich diet was fed to male rats for 2 weeks. After the feeding period, blood and tissue samples were collected, and their astaxanthin levels were evaluated. The -isomer-rich astaxanthin diet resulted in higher levels of astaxanthin in blood and many tissues (in particular, skin, lung, prostate, and eye) compared to the all--isomer-rich diet. Moreover, the -isomer-rich diet enhanced the level of the 13-isomer in blood and tissues rather than that of the 9-isomer. These results strongly supported that astaxanthin -isomers have greater bioavailability and tissue accumulation efficiency than the all--isomer. Moreover, (13)-astaxanthin would have higher bioavailability and tissue accumulation than the other isomers.