Abstract
Purpose: :
Lutein (L) and zeaxanthin (Z) are distributed relatively equally between LDL and HDL in serum. However, the mechanism by which they are delivered to the macula, where they are referred to as macular pigment (MP), is poorly understood. This study investigated the relationship between the MP carotenoids, lutein (L) and zeaxanthin (Z), serum lipoproteins and MP optical density (MPOD).
Methods: :
We recruited 331 healthy subjects for this study. Demographic and health details were recorded. Fasting blood samples were taken for lipoprotein analysis by spectrophotometric assay (Alfa Wassermann ACE® Clinical Chemistry System), and L and Z analysis by high performance liquid chromatography. MPOD was measured by heterochromatic flicker photometry using the Macular DensitometerTM.
Results: :
The mean ± SD age of our subjects was 48.27 ± 10.99; 232 (70.1%) were female. Five (1.5%) of the 331 subjects could not use the Macular DensitometerTM adequately. There was a statistically significant relationship between both serum L and Z, and average MPOD across the macula (r=0.4, p<0.000; and r=0.169, p=0.002, respectively). There was a statistically significant positive relationship between serum L and total cholesterol (r=0.237, p<0.000) and between serum L and HDL (r=0.269, p<0.000), and there was an inverse relationship between serum L and triglycerides (r=-0.125, p=0.023). After controlling for age, BMI, sex, MPOD, smoking, and serum Z, the positive relationships remained significant; however, the inverse relationship with serum triglycerides lost statistical significance. There was no statistically significant relationship between serum Z and lipoproteins.
Conclusions: :
Our findings support the role of HDL as a transporter of L to the macula where it forms part of the MP. The precise mechanisms by which the MP carotenoids are delivered to, and taken up by, the macula require further study.
Keywords: age-related macular degeneration • carotenoids/carotenoid binding proteins • macula/fovea