A Possible Role for the Antioxidants Lutein and Zeaxanthin in Protecting against Age-Related Increases in Lens Density

Abstract

Epidemiological data have identified a number of factors that influence risk of developing age-related cataract (ARC). For instance, factors that promote (eg smoking and light exposure) and factors that protect (eg antioxidants) against oxidative stress to the crystalline lens appear to increase and decrease risk of ARC, respectively. Although biochemical studies consistently support a protective role for antioxidants, the epidemiological data are inconsistent. Since ARC is a condition with a protracted latency period, it is possible that the inconsistencies present in the epidemiological literature may be due to the focus on cataractous patients. We focused on the lens health of individuals prior to cataract. Lens health was determined by measuring the optical density (OD) of the lens with a psychophysical technique. OD characterises many of the biochemical changes of the lens and is part of many systems used to classify ARC. Variance in lens OD, stratified by age, was examined for its relationship to variables thought to be important to the etiology of ARC. We report results for the relationship of lens OD to the antioxidants lutein and zeaxanthin (L and Z). For older individuals (>48 years) we noted a significant inverse relationship between dietary intake of L and Z and lens OD (n=39, r=−0.34, p<0.015). This was not the case for younger individuals (24 – 36 years). This relationship is increased when L and Z are measured directly in the retina is a psychophysical technique. For older individuals, retinal L and Z (ie macular pigment) are inversely related to lens OD (n=51, r=-0.47, p<0.001). These data are consistent with a role of L and Z in protecting against age-related increases in the OD of the crystalline lens.