Long Term Objectives: Age-related macular degeneration (AMD) is the leading cause of blindness in the United States. Low dietary intake or low blood levels of lutein and zeaxanthin, which are the only pigments found in the macular region of the human retina, has been associated with an increased risk for AMD. We have reported that the dietary supplementation of lutein and zeaxanthin can increase the macular pigments (MP) of the eye. MP effectively absorbs blue light as well as quenches reactive oxygen species (ROS). Green tea polyphenols are also effective scavenger of ROS in vitro. However, the bioavailability and biological functions of tea polyphenols in humans are far from being understood. Our goal is to elucidate how to effectively increase MP by physiologic levels of antioxidant supplementation. We focus our attention on the antioxidant functions of lutein and tea polyphenols in relation to AMD. We hypothesize that lutein and tea polyphenols protect the macula of the eye by increasing MP carotenoids effectively through an antioxidant mechanism. ? ? Specific Aims:
Aim 1) To determine the changes of MP density of the eye and changes of antioxidant capacity of circulation using our newly developed assay when consuming lutein, which is a major MP. ? Aim 2) To determine the possible synergistic effect of lutein and green tea extract on MP density and antioxidant capacity of circulation using our sensitive assay. Research Design and Methods: Forty-four men & post-menopausal women (all 50-70 yrs) will be randomly assigned to be supplemented with either 1) lutein (12 mg/d), or 2) lutein (12 mg/d) + green tea extract (400 mg/d) for 16 wks. Macular pigment density will be determined monthly using heterochromatic flicker photometry. The spatial distribution curve of MP will be obtained. Blood samples will be collected monthly for analyses of 1) antioxidant capacity in both the lipophilic and hydrophilic compartments of plasma by fluorescence methods; 2) lipid peroxidation (MDA-TBA adducts) by HPLC; 3) epigallocatechin gallate, major component of green tea extract, & its metabolites, and lutein & zeaxanthin levels by HPLC. ? This study will allow us to obtain new information regarding biological functions of antioxidants on human MP and to characterize factors that might predict individual differences in response to lutein supplementation. ? ? Due to the budgetary limitations, we are proposing to study only two groups (I, Lutein; II, Lutein + green tea extract), with 22 study participants in each group for an 18-wks period of intervention. If we obtain positive results from the current study, we plan to submit a larger (R01) proposal, which would 1) increase the study groups to four (I, Placebo; II, Lutein; III, green tea extract; IV, lutein + green tea extract) and 2) determine how long the increased macular pigments can be sustained once the intervention has been discontinued. ? ?
| Li, Lei; Chen, C-Y Oliver; Aldini, Giancarlo et al. (2010) Supplementation with lutein or lutein plus green tea extracts does not change oxidative stress in adequately nourished older adults. J Nutr Biochem 21:544-9 |
| Yeum, Kyung-Jin; Beretta, Giangiacomo; Krinsky, Norman I et al. (2009) Synergistic interactions of antioxidant nutrients in a biological model system. Nutrition 25:839-46 |
| Li, L; Duker, J S; Yoshida, Y et al. (2009) Oxidative stress and antioxidant status in older adults with early cataract. Eye (Lond) 23:1464-8 |
