Plasma kinetics of lutein, zeaxanthin, and 3-dehydro-lutein after multiple oral doses of a lutein supplement.
BACKGROUND: Adequate intake of lutein is postulated to reduce the risk of age-related macular degeneration, but kinetic information for developing a dosing regimen is sparse. OBJECTIVE: The objective was to characterize lutein plasma kinetics in a multiple dosing design and to assess the effects of lutein intake on concentrations of other plasma carotenoids. DESIGN: After a run-in period of 7 d, 19 healthy volunteers were assigned to receive daily oral doses of 4.1 mg lutein (n = 8; group 1) or 20.5 mg lutein (n = 8; group 2) for 42 d or no lutein (n = 3; control group). The supplement contained 8.3% zeaxanthin relative to lutein (100%). The time profiles of plasma xanthophyll concentrations were monitored over the dosing phase, and samples were collected frequently on day 42 and for 24 d after dosing. RESULTS: Average plasma all-E-lutein concentrations increased from 0.14 to 0.52 +/- 0.13 and 1.45 +/- 0.69 micromol/L in groups 1 and 2, respectively. Dose-normalized lutein bioavailability in group 2 was approximately 60% of that in group 1. Kinetic disposition half-life did not differ significantly between groups. On average, dosing for 18 d was required to reach a >90% fraction of the steady state concentration, which is consistent with an effective half-life for accumulation of approximately 5.6 d. Plasma kinetics of all-E-lutein were paralleled by those of all-E-3-dehydro-lutein. Kinetic analysis indicated formation of all-E-3-dehydro-lutein from lutein. Lutein was well tolerated and did not affect the concentrations of other carotenoids. CONCLUSION: Long-term supplementation with 4.1 and 20.5 mg lutein as beadlets increased plasma lutein concentrations approximately 3.5- and 10-fold, respectively.