title: Bioavailability of a natural isomer mixture compared with synthetic all-trans beta-carotene in human serum.
abstract: The unicellular alga Dunaliella bardawil was shown previously to contain very high concentrations of beta-carotene composed of about equal amounts of the all-trans and 9-cis isomers, which differ in their physicochemical features and antioxidative activity. The uptake of alpha- and beta-carotenes, oxycarotenoids, and other lipophilic substances from a basal diet supplemented with synthetic beta-carotene or dry D. bardawil power was studied in humans. Subjects were given a basal diet supplemented daily with 40 mg beta-carotene, synthetic or natural, for a relatively short period of 14 d. Serum analyses at the end of this period detected mainly oxycarotenoids, and to a lesser extent all-trans beta-carotene and alpha-carotene, but not 9-cis beta-carotene. Retinol was increased by the all-trans beta-carotene diet. A high amount of oxidized dienic, lipophilic polar products was exhibited in HPLC predominantly in sera from the placebo and synthetic all-trans beta-carotene groups by strong, short ultraviolet absorbance peaks of 232 nm. The preferential serum absorption of all-trans beta-carotene over 9-cis beta-carotene, in parallel with the appearance of a high concentration of oxidized dienic products with supplementation of the basal diet with all-trans beta-carotene compared with the low concentration of serum-oxidized dienic products with supplementation with a natural beta-carotene source, suggests that 9-cis beta-carotene acts as an in vivo lipophilic antioxidant more efficiently than does all-trans beta-carotene.
authors.affiliation: National Institute of Oceanography, Israel Oceanographic and Limnological Research, Haifa.
authors.forename: A
authors.initials: A
authors.lastname: Ben-Amotz
authors.forename: Y
authors.initials: Y
authors.lastname: Levy
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000737:chemistry / Q000493:pharmacokinetics*; D001682:Biological Availability; D002338:Carotenoids / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics*; D000460:Chlorophyta / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007536:Isomerism; D008297:Male; D014801:Vitamin A / Q000097:blood; D014810:Vitamin E / Q000097:blood; D019207:beta Carotene
chemical_list: D000975:Antioxidants; D019207:beta Carotene; D014801:Vitamin A; D014810:Vitamin E; D002338:Carotenoids