All-trans beta-carotene preferentially accumulates in human chylomicrons and very low density lipoproteins compared with the 9-cis geometrical isomer.
Following ingestion of a beta-carotene isomer mixture (Betatene) containing nearly equal amounts of all-trans and 9-cis beta-carotene (all-trans/9-cis beta-carotene ratio approximately 1.5), concentrations of all-trans beta-carotene increased for 6 or 8 h in the chylomicron fraction of plasma from four of seven human subjects. A substantially lower increase in the 9-cis beta-carotene concentration was observed, with the accumulation of the all-trans isomer being 10- to 50-fold higher than that of the 9-cis isomer, calculated on the basis of the beta-carotene isomer pattern in the ingested mixture. A similar effect was observed in the VLDL fraction. Three of the seven subjects did not respond to beta-carotene ingestion. In the subjects that did respond, the all-trans/9-cis beta-carotene ratios in chylomicrons and VLDL suggest an efficient isomer-selective mechanism for intestinal uptake across the mucosa or very rapid elimination into tissues.
Stahl
W
W
Institut für Physiologische Chemie I, Heinrich-Heine-Universität Düsseldorf, Germany.
Schwarz
W
W
von Laar
J
J
Sies
H
H
D000284:Administration, Oral; D000328:Adult; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D002338:Carotenoids / Q000008:administration & dosage / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D002914:Chylomicrons / Q000378:metabolism*; D006801:Humans; D008079:Lipoproteins, VLDL / Q000097:blood / Q000378:metabolism*; D008875:Middle Aged; D013237:Stereoisomerism; D019207:beta Carotene
D000970:Antineoplastic Agents; D002914:Chylomicrons; D008079:Lipoproteins, VLDL; D019207:beta Carotene; D002338:Carotenoids