Assessment of lutein and zeaxanthin dietary intake and status biomarkers and lipid profile as potential determinants of macular pigment optical density in subjects over 45 y

Abstract

Lutein (L) and zeaxanthin (Z) accumulate in retina (macular pigment). Their adequate status (serum concentrations, macular pigment optical density [MPOD]) is associated with a lower risk of age-related macular degeneration. The MPOD showed age-specific correlations with the L and Z intake and serum concentrations (1), showing strongest correlations in older vs younger adults (1,2). Aim: to assess the L and Z dietary intake and status biomarkers (serum concentrations and MPOD), the correlations among them and with the visual function (contrast sensitivity) (preliminary data are shown). Methods and subjects: L and Z concentrations were analyzed in serum, dietary intake and MPOD in subjects aged 45-65y (n=155). Inclusion criteria: cholesterolemia (<250mg/dl), BMI (<30kg/m2), varied diet, no dietary supplements intake, no drugs/foods to lower cholesterol, no chronic diseases. L and Z in fasting blood by HPLC, MPOD by heterochromic flicker photometry (MPS-9000 desktop device) (1). Lipid profile by colorimetric enzyme assays. Dietary intake by three 24 h recalls and a carotenoid database and software (3,4). Results: Serum concentrations as mean±SD (median): lutein: 19,6±9,1 (17,8), zeaxanthin: 5,1±2,9 (4,6)(¿g/dl). Dietary intake (¿g/day): L+Z: 1584±1546 (1002). MPOD (density units, n=310): 0,33 ±0,14 (0,34). Significant correlations (Spearman¿s ¿, p value): MPOD¿Serum: L (0,170, p=0,003), Z (0,129, p=0,023), L+Z (0,169, p=0,003), L+Z/cholesterol (0,114, p=0,044). MPOD-dietary intake and MPOD- serum lipids: no significant correlations were found. Numerous and highly significative correlations were found between L+Z in dietary intake, in serum and with cholesterol and HDL. Although no L/Z dietary supplements intake were declared by any subjects, some of them (n=12) showed much higher serum concentrations than those that could be obtained by dietary means, thus, the group was split considering a cut-off point of 33 ¿g/dL as ¿physiological¿ concentration for normolipemics (1). Multiple linear regression analysis showed serum zeaxanthin, lutein/HDL, zeaxanthin/HDL as predictors of the MPOD (R2 5,8%) only for subjects with serum lutein ¿ 33 ug/dL, but not in the whole sample. Conclusions: 1) These L and Z serum concentrations and MPOD values contribute to the establishment of normal /reference ranges for subjects aged 45-65y. 2) serum zeaxanthin, lutein/HDL and zeaxanthin/HDL are predictors for the MPOD only in normolipemic subjects with serum lutein concentrations within a range achievable by dietary means.