Changes in macular pigment optical density and serum concentrations of its constituent carotenoids following supplemental lutein and zeaxanthin: The LUNA Study

Macular pigment (MP), consisting of lutein (L) and zeaxanthin (Z), is believed to protect the retina from photo-oxidative damage. The current study investigates, in terms of MP optical density (MPOD) and serum concentrations of its constituent carotenoids, response to supplemental L and Z, and co-antioxidants. An intervention (I) group, consisting of 108 subjects (mean [SD] age: 71.5 [7.1] years), of which 92.6% exhibited features of age-related macular degeneration (AMD), received a daily supplement consisting of 12 mg L and 1 mg Z, both provided as ester 120 mg vitamin C, 17.6 mg vitamin E, 10 mg zinc, 40 mg selenium (Ocuvite Lutein) for a period of 6 months. MPOD was measured, by 2-wavelength autofluorescence (AF), on five occasions during the period of supplementation, and once again 3 months following discontinuation of the supplement. A control (C) group of 28 subjects (mean [SD] age: 71.0 [8.1] years), who received no dietary supplementation or modification, was examined at baseline and once again after a mean of 29.4 (9.3) weeks. At baseline, mean (SD) MPOD (at 0.5) was 0.504 (0.197) and 0.525 (0.189) in the I and C groups, respectively. There was a statistically significant increase in MPOD (at 0.5) for the I group (0.1 [0.009]; p < 0.0008), whereas no significant increase was seen in the C group (0.03 [0.02]; p > 0.05), over the period of supplementation. In order to classify supplemented subjects into quartiles, in terms of MPOD response, we calculated the difference between MPOD (at 0.5) at visit 6 and at baseline (visit 1). Quartile 1 (the ‘‘non-responder’’ quartile) displayed no increase in MPOD (at 0.5), in spite of rises seen in serum concentrations of L and Z. The three ‘‘responder’’ quartiles reached similar final plateaus of MPOD (at 0.5), reflected in final mean (SEM) values of 0.59 (0.04) optical density unit (ODU), 0.64 (0.03) ODU and 0.64 (0.03) ODU for quartiles 2, 3 and 4, respectively. Subjects with low baseline MPOD were more likely to exhibit a dramatic rise in MPOD, or to exhibit no rise in MPOD, in response to supplements than subjects with medium to high baseline MPOD values. Supplementation with 12 mg L and 1 mg Z, combined with co-antioxidants, resulted in an increase of MPOD at 0.5 eccentricity in a majority of subjects, including those afflicted with AMD. However, there remains a substantial proportion of subjects for whom, in spite of rises in serum concentrations of L and Z in these subjects, MPOD augmentation in response to supplemental L, Z and co-antioxidants could not be detected over the study period, thus indicating that intestinal malabsorption of these carotenoids is not responsible for the lack of a macular response to such supplements. Further, our results suggest that saturable mechanisms play a role in the retinal capture and/or stabilisation of the macular carotenoids