Background & aims: Lutein and zeaxanthin accumulate in retina (macular pigment). Their nutritional status can be assessed using dietary or biochemical markers and both have been associated with macular pigment optical density. We proposed to assess dietary and status markers of lutein and zeaxanthin in a group of healthy Spanish volunteers, considering the potential influence of age, gender and serum lipids to investigate the predictors of the macular pigment optical density.
Methods: Serum lutein and zeaxanthin concentrations, dietary intake and macular pigment optical density were determined in 108 healthy men and women (20-35 and 45-65 years), using high-performance liquid chromatography, 3-day food records and heterochromic flicker photometry, respectively. Mann-Whitney U-test, Spearman correlation coefficient and multivariate regression analysis were used for the statistical study.
Results: Serum concentrations and dietary intake of lutein plus zeaxanthin (p < 0.0001 and p = 0.001, respectively) were higher in older vs younger subjects, whereas macular pigment optical density was lower (p = 0.038). The highest correlation coefficients between intake and serum were for fruit and serum lutein (ρ = 0.452, p < 0.0001) and for fruit and lutein + zeaxanthin (ρ = 0.431, p < 0.0001) in the younger group. Macular pigment optical density correlated with serum xanthophylls (ρ = 0.223, p = 0.02) and fruit and vegetable intake (ρ = 0.350, p = 0.0002), showing highest correlations when lutein and zeaxanthin were expressed in relation to serum lipids in older subjects (ρ = 0.262, p = 0.006). Multivariate regression analysis identified age and serum lutein as major predictors of macular pigment optical density (total sample), and a coefficient of determination of 29.7% for the model including lutein + zeaxathin/cholesterol + triglycerides, sex and fruit + vegetables in the older group.
Conclusions: The establishment of normal/reference ranges for serum lutein and zeaxanthin should consider age ranges and be expressed in relation to lipid concentrations, at least in subjects over 45 years, as this could influence macular pigment optical density. The macular pigment optical density showed age-specific correlations with lutein plus zeaxanthin expressed in relation to serum lipid concentrations as well as with the fruit and vegetable intake.