Differential Relationships Between Serum Xanthophylls and Macular Pigment and Retinal Morphology

Abstract

Abstract Objectives Lutein and zeaxanthin are xanthophyll carotenoids that comprise macular pigment in the eye and disproportionately accumulate in brain tissue. While the link between serum xanthophylls and macular pigment has received considerable investigation, comparatively less is known regarding the relationship between circulating xanthophylls and retinal morphology. This knowledge gap is significant since deterioration of the morphometric measures of the retina (e.g., retinal nerve fiber layer, RNFL) is a feature of age-neurodegenerative diseases. This project aimed to understand the relationship between serum xanthophylls and retinal morphology. Methods Subjects included 84 individuals (30 males) with overweight and obesity (BMI ≥ 25 kg/m2) between 25–45 years. Macular pigment optical density (MPOD) was measured using heterochromatic flicker photometry. Optical coherence tomography (OCT) was used to assess RNFL, ganglion cell layer (GCL), and inner plexiform layer (IPL). Venous blood draws were used to assess serum lutein and zeaxanthin. Covariates assessed included demographic factors, adiposity (DXA), and dietary intake (7d food records). Results Serum lutein (r = 0.32, P < 0.01) and zeaxanthin (r = 0.23, P = 0.01) concentrations were associated with greater MPOD. There were no significant associations between serum xanthophyll concentrations and morphological values. Similarly, there was no influence of adiposity or dietary lutein and zeaxanthin on retinal morphological measures. However, overall diet quality, assessed using Healthy Eating Index (HEI) was positively associated with IPL (r = 0.35, P < 0.01) and GCL (r = 0.32, P < 0.01) thickness. Conclusions Although circulating carotenoids were associated with macular pigment, this relationship did not extend to morphological measures in the retina. However, overall dietary quality was significantly associated with retinal morphological measures. These findings suggest that macular pigment and retinal morphology may be influenced by nutritional factors. Funding Sources Hass Avocado Board.