Lutein, zeaxanthin, and meso-zeaxanthin: The basic and clinical science underlying carotenoid-based nutritional interventions against ocular disease

Abstract

The human macula uniquely concentrates three carotenoids: lutein, zeaxanthin, and meso-zeaxanthin. Lutein and zeaxanthin must be obtained from dietary sources such as green leafy vegetables and orange and yellow fruits and vegetables, while meso-zeaxanthin is rarely found in diet and is believed to be formed at the macula by metabolic transformations of ingested carotenoids. Epidemiological studies and large-scale clinical trials such as AREDS2 have brought attention to the potential ocular health and functional benefits of these three xanthophyll carotenoids consumed through the diet or supplements, but the basic science and clinical research underlying recommendations for nutritional interventions against age-related macular degeneration and other eye diseases are underappreciated by clinicians and vision researchers alike. In this review article, we first examine the chemistry, biophysics, and physiology of these yellow pigments that are specifically concentrated in the macula lutea through the means of high-affinity binding proteins and specialized transport and metabolic proteins where they play important roles as short-wavelength (blue) light-absorbers and localized, efficient antioxidants in a region at high risk for light-induced oxidative stress. Next, we turn to clinical evidence supporting functional benefits of these carotenoids in normal eyes and for their potential protective actions against ocular disease from infancy to old age.

Genetic dissection in a mouse model reveals interactions between carotenoids and lipid metabolism

“…cancer (5,6,9,10). However, the effects of carotenoids on mammalian physiology are not well defined because of the dual role of these compounds as parent compounds and precursors for apocarotenoid production.…”

Mechanisms of selective delivery of xanthophylls to retinal pigment epithelial cells by human lipoproteins

“…It is hypothesized that lutein is converted to meso-zeaxanthin either enzymatically or induced by light (14,15). Thus, primates given a xanthophyll-free diet from birth followed by a lutein supplement showed the presence of mesozeaxanthin in the retina, while those provided no xanthophylls or with just zeaxanthin alone did not have meso-zeaxanthin in the retina (16).…”

Fluorescence lifetime imaging ophthalmoscopy

“…They play an important role as antioxidants to prevent against oxidative stress (Bernstein et al, 2016). Due to the absorbance maximum of lutein and zeaxanthin around 460 nm, both compounds act as blue filters for UV light (Barker et al, 2011).…”