Macular pigment optical density at four retinal loci during 120 days of lutein supplementation

Abstract

Abstract: : Purpose: Intake of dietary carotenoids may impact one’s risk for atherosclerosis, various cancers, and age–related macular degeneration (AMD). Two carotenoids, lutein (L) and zeaxanthin (Z), are associated with AMD risk due to their selective deposition in the macula. The macular carotenoids, referred to as macular pigment (MP), may inhibit the pathogenesis of AMD by reducing both oxidative and light stress. Several investigations reported the effects of lutein supplementation on retinal L and Z concentrations, defined as macular pigment optical density (MPOD), but few studies used frequent measures over time. The aim of this study was to measure systematic changes in MPOD at four retinal eccentricities during 120 days of lutein intervention. Methods: MPOD was measured at 20’, 30’, 60’ and 120’ in the nasal hemiretina using heterochromatic flicker photometry. The test stimuli were presented in free–view with a Macular Metrics® densitometer. Two male subjects consumed 60mg of lutein esters (equal to 30mg free lutein) per day for 120 consecutive days. MPOD measures were performed 3 to 4 days per week, and blood samples were collected at baseline and in four–week intervals. High–performance liquid chromatography was used to analyze serum carotenoid concentrations. Results: Mean serum L increased from 0.15ug/mL at baseline to 2.68ug/mL after four weeks of intervention, and remained at this elevated level throughout the supplementation period. The mean baseline MPOD for subject one was 0.496, 0.404, 0.236, and 0.025 at 20’, 30’, 60’ and 120’, respectively. The mean baseline MPOD for subject two was 0.656, 0.512, 0.195, and 0.056. After 120 days of intervention, both subjects’ MPOD increased approximately 0.08 at the two central eccentricities, despite their dissimilar baseline MPOD. At the 60’ and 120’ loci, subject one’s MPOD appeared to increase approximately 0.03, whereas linear fits of subject two’s data at these eccentricities had slight negative slopes. Conclusions: As with previous studies, L supplementation increased MPOD; however, the increase was not uniform across the retina. Instead, greater increases in MPOD were observed at the two central loci, suggesting that L deposition may be biased toward the central retina.

Keywords: macular pigment • age–related macular degeneration • carotenoids/carotenoid binding proteins