Abstract
Abstract: :
Purpose:Lutein and zeaxanthin, the primary constituents of macular pigment (MP), are derived from the diet. Previous research has demonstrated that increased consumption of spinach, a food rich in lutein and zeaxanthin, or a pharmacological dose of lutein supplement can significantly increase macular pigment optical density (MPOD) in some subjects. A direct comparison of previous findings, however, is difficult due to the various methodologies. The objective of the current project was to compare the bioavailability of two concentrations of lutein from either supplements or spinach. Methods: 50 volunteers were assigned to one of 5, 12–week interventions: (1) placebo pill consumed every day; (2) 10mg of lutein supplement consumed 5 days per week; (3) 30mg of lutein supplement consumed every day; or (4, 5) ½ cup of spinach consumed 5 days per week. Two different cultivars of spinach were used, one that provided 9mg of lutein (S1) and another that provided 12mg of lutein (S2). MPOD was measured at four retinal loci (20', 30', 60', and 120') with heterochromatic flicker photometry at baseline and after 12 weeks of intervention. Serum carotenoid concentrations were measured from fasting blood samples collected at baseline and after 12 weeks. Results: Mean serum lutein concentrations significantly increased in both the 30mg supplement group (p=0.029) and the S2 group (p=0.044). No significant changes in serum carotenoids were observed in individuals who consumed placebo, 10mg of lutein supplement, or S1. Further, MPOD did not significantly change at any eccentricity in these three groups. In the 30mg supplement group, MPOD significantly increased at 20' (p=0.01), 30' (p<0.001), and 60' (p=0.04) eccentricity. Likewise, mean MPOD significantly increased at 20' (p=0.02), 30' (p=0.01), and 60' (p=0.01) eccentricity in the S2 group. The mean increases in MPOD for the 30mg supplement group and S2 group were 0.071, 0.052, and 0.041 log units at 20', 30', and 60' eccentricity, respectively. Conclusions: The daily consumption of 30mg of lutein from supplements or 12mg of lutein from spinach consumed 5 days per week significantly increased MPOD at central retinal loci after 12 weeks of intervention. A longer intervention period may be necessary to observe significant increases in MPOD with either 10mg of lutein supplement or spinach when consumed 5 days per week.
Keywords: macular pigment • carotenoids/carotenoid binding proteins • retina