Abstract
Purpose: :
Lutein and zeaxanthin are important carotenoid pigments accumulating in the human macula. We tested if oral administration of these carotenoids affects the macular pigment density in normal subjects.
Methods: :
Eighteen healthy volunteers were included in the study (mean age = 40.2 +/-8.2 years; 9 men, 9 women). Each subject was randomly assigned to either the lutein (L; n=9) or zeaxanthin (Z; n=9) group, and a daily dose of 10 mg lutein or zeaxanthin was orally administered. The macular pigment optical density (MPOD) was measured in both eyes of before supplementation, and once every month up to three months total during the supplementation phase, using Raman spectrophotometry (RSP) and autofluorescence imaging (AFI) techniques. The MPODs measured from both eyes of a subject were averaged and compared between RSP and AFI using linear regression analysis. The factors associated with RSP-measured MPOD were analyzed using multiple regression analysis. Intra-and inter-group differences of RSP-measured MPOD in the L and Z groups were analyzed by repeated-measurement MANOVA.
Results: :
MPODs measured by RSP and AFI were significantly correlated with each other at all time points, both in the L and Z groups (r = 0.45 - 0.81). The myopic refractive error was significantly associated with low MPOD levels (p = 0.0005), while age and sex were not associated. When excluding subjects with myopia greater than -6D, the mean (+/- SE) RSP-measured MPODs in a 1 mm diameter spot centered on the fovea before and after 3-month supplementation were 5653 +/- 476 and 7513+/-581, respectively, in the L group. In the Z group, the MPODs were 5714 +/- 747 and 6049+/-779, respectively. During supplementation, a significant increase of MPOD was observed in the L group (F = 4.929, p=0.0113), while in the Z group (F=0.494, p=0.6918) the levels remained unchanged, and the difference in MPODs between the L and Z groups reached borderline (p=0.0857).
Conclusions: :
MPOD measured by two different techniques correlates significantly. Oral lutein increases MPOD more effectively than oral zeaxanthin in normal subjects.
Keywords: macular pigment • imaging/image analysis: clinical