There is observational evidence, supported on theoretical grounds, for an inverse correlation between the amount of macular pigment (MP) in an individual's retina and the risk of acquiring age-related macular degeneration (AMD) Preliminary results from a small number of human subjects have shown that dietary supplementation with either lutein or zeaxanthin, which constitute the MP, can significantly increase the subjects' MP density. These results, if corroborated for the population at large, would provide relevant and subjects' MP density. These results, if corroborated for the population at large, would provide relevant and important information for the design of a clinical intervention study. Such a study would determine the efficacy of these two carotenoids in preventing the onset of the devastating, and as yet incurable, disease, AMD.
Specific aim 1 of the proposed study is to investigate the effects of lutein supplementation, at different dosages, of lutein concentration in the blood serum and on the density of MP in 120 healthy human subjects. (Lutein is commercially available as a supplement; zeaxanthin is not.) It is our hypothesis that there will be a dose-dependent rate of accumulation of lutein within the macula. The results of the study will provide necessary information for determining the appropriate dose needed to produce an acceptable level of MP density within a given time-frame. The study will also quantify differences in response to supplementation among subjects, and will seek causes. In addition, the influence of a subject's age and gender will be determined. MP density in each subject will be measured frequently throughout the supplementation period by heterochromatic flicker photometry. The concentration of lutein in the subjects' serum will be measured regularly by high performance liquid chromatography MP density using the anticipated pool of 120 subjects in specific aim 1. AMD has been shown to be more prevalent in females compared with males, and in subjects with lighter irises.
Specific aim 3 is to determine whether metabolites of lutein observed in the serum are accumulated in the retina and/or whether specific metabolites are formed in the retina. Liquid chromatography/mass spectroscopy (LC/MS) will be used to quantify the accumulation of oxidized lutein metabolites in the serum of the 120 subjects in specific aim 1, the subsequent elimination of the metabolites from the serum, as well as to aid in the identify of the metabolites. Finally, 30 donor eyes will be analyzed by LC/MS to determine which, if any, of the metabolites accumulates, or is formed, in the retina.
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