title: Kinetics of 14C distribution after tracer dose of 14C-lutein in an adult woman.
abstract: Lutein is an oxygenated carotenoid (xanthophyll) found in dark green leafy vegetables. High intakes of lutein may lower the risk of age-related macular degeneration. Current understanding of human lutein metabolism as it might occur in vivo is incomplete. Therefore, we conducted a feasibility study where we dosed a normal adult woman with 14C-lutein (125 nmol, 36 nCi 14C), dissolved in olive oil (0.5 g/kg body weight) and mixed in a banana shake. Blood, urine, and feces collected before the dose was administered served to establish baseline values. Thereafter, blood was collected for 63 d following the dose, while feces and urine were collected for 2 wk post-dose. The 14C contents in plasma, urine, and feces were measured by accelerator MS. The 14C first appeared in plasma 1 h after dosing and reached its highest level, approximately2.08% of dose/L plasma, at 14 h post-dose. The plasma pattern of 14C did not include a chylomicrons/VLDL (intestinal) peak like that when the same subject received 14C-beta-carotene (a previous test), suggesting that lutein was handled differently from beta-carotene by plasma lipoproteins. Lutein had an elimination half-life (t1/2) of approximately10 d. Forty-five percent of the dose of 14C was eliminated in feces and 10% in urine in the first 2 d after dosing. Quantifying human lutein metabolism is a fertile area for future research.
authors.affiliation: Department of Nutrition, University of California Davis, 95616-8669, USA.
authors.forename: Fabiana F
authors.initials: FF
authors.lastname: de Moura
authors.forename: Charlene C
authors.initials: CC
authors.lastname: Ho
authors.forename: Girma
authors.initials: G
authors.lastname: Getachew
authors.forename: Sabrina
authors.initials: S
authors.lastname: Hickenbottom
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Clifford
mesh_terms: D000284:Administration, Oral; D019540:Area Under Curve; D001682:Biological Availability; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics*; D005243:Feces / Q000737:chemistry; D005260:Female; D006801:Humans; D014975:Lutein / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D008875:Middle Aged
chemical_list: D002250:Carbon Radioisotopes; D014975:Lutein