Abstract
Purpose:
Research has been ongoing into the role of macular pigment (MP) for vision and age-related macular degeneration (AMD). MP is comprised of the dietary carotenoids lutein (L), zeaxanthin (Z) and meso-zeaxanthin (MZ). MZ may be important given its predominance over L and Z at the central fovea, due to its strong antioxidant properties, and its capacity to filter short wavelength (blue) light, but few studies have investigated MP response to MZ supplements. This study reports on MP optical density (MPOD) response to three different MP supplements (two containing MZ) in normal subjects (n 36) and in subjects with AMD (n 28).
Methods:
Subjects were randomly assigned to: Group 1 (20 mg L, 2 mg Z), Group 2 (10 mg L, 2 mg Z, 10 mg MZ) or Group 3 (3 mg L, 2 mg Z, 17 mg MZ). MPOD was measured at central and peripheral eccentricities (0.25, 0.5, 1.0 and 1.75) using customised heterochromatic flicker photometry. MPOD was assessed at baseline and every two weeks over an eight week study period.
Results:
The MPOD response of AMD subjects was comparable to that of normal subjects, with the exception of Group 2, where AMD subjects demonstrated a greater MPOD response (AMD: 0.179 ± 0.075; Normal: 0.137 ± 0.070; P=0.024) at an eccentricity of 1.75. MPOD at 0.25 eccentricity increased significantly in Group 1 (0.095±0.066 [22%]; P<0.001) and Group 2 (0.147±0.078 [34%]; P<0.001), and in Group 3 (0.0906±0.100 [19%]; P=0.003). MPOD at 0.5 eccentricity increased significantly in Group 1 (0.103±0.076 [30%]; P<0.001), Group 2 (0.129±0.076 [37%]; P<0.001), and in Group 3 (0.088±0.095 [23%]; P=0.002). MPOD at 1.0 eccentricity increased significantly in Group 1 (0.079±0.065 [35%]; P<0.001), Group 2 (0.072±0.051 [31%]; P<0.001), and in Group 3 (0.052±0.066 [19%]; P<0.007). MPOD at 1.75 eccentricity increased significantly in Group 1 (0.056±0.055 [44%]; P<0.001) and Group 2 (0.057±0.044 [55%]; P<0.001), but not in Group 3 (0.019±0.062 [12%]; P=0.242).
Conclusions:
The formulation containing all three macular carotenoids (Group 2) was most efficacious in terms of enriching MPOD across all measured eccentricities. Of interest, Group 3 (the high MZ group) enriched central MPOD, but not peripheral MPOD. This data is consistent with recent publications demonstrating a beneficial effect of including MZ in a supplement, particularly for increasing central MPOD.
Keywords: 412 age-related macular degeneration •
444 carotenoids/carotenoid binding proteins •
587 macular pigment