Serum Lutein and Zeaxanthin Support Retinal Vasculature Health in Older Adults

by | Dec 4, 2018 | 2018, Antioxidants, Eye Health, Lutein, Zeaxanthin

Written by Angeline A. De Leon, Staff Writer. This study demonstrates how the antioxidant carotenoids lutein and zeaxanthin may support retinal microcirculation to maintain efficient blood flow and to prevent the onset of subclinical vascular diseases.

eye healthThe retinal vascular system allows for a non-invasive study of microcirculation (the flow of blood through the smallest vessels of the circulatory system) 1. Changes observed in retinal blood vessels are thought to be reflective of general vascular function, and retinal vascular parameters have, therefore, been used as markers of systemic diseases such as atherosclerosis, heart disease, and stroke 2-4. Studies also indicate that alterations in the retinal vascular system can predict later development of ocular diseases such as diabetic retinopathy and age-related macular degeneration 5,6. Among the many factors that may determine retinal vascular features are age, birth weight, obesity, physical activity level, and genetics 2. One study reports that a specific quantitative measure of retinal vasculature (retinal arteriolar caliber) is linked to inflammation (lower glutathione peroxidase activity, an antioxidant defense system) 7, suggesting that retinal microcirculation may also be impacted by oxidative stress. Based on findings, a recent Chinese study published in PloS ONE (2018) sought to evaluate the relationship between carotenoids lutein and zeaxanthin (biological antioxidants associated with protective effects against age-related macular degeneration) 8-11 and retinal vascular parameters, examining the link between serum concentrations of carotenoids and measures of retinal vasculature in older subjects.

A total of 128 healthy older Singaporean subjects (mean age = 54.1 +/- 7.41 years) were recruited in a cross-sectional study. A digital retinal camera was used to photograph each eye, and quantitative retinal vascular parameters (arteriolar/venular caliber, representing average diameter of arterioles and venules of eye; branching angle; tortuosity, reflecting straightness/curliness of vessels; and fractal dimension, representing branching pattern) were measured from the photograph using a semi-automated computer-assisted program. Fasting venous blood samples were also collected to determine serum concentrations of carotenoids.

Multiple linear regression analyses (controlling for age, gender, body mass index, total cholesterol, and other confounding variables) revealed a significant relationship between concentration level of carotenoids and indices of retinal vasculature: decreased serum lutein was associated with one standard deviation (SD) decrease in retinal arteriolar caliber [β = 0.045 (0.003 to 0.086), p = 0.036], one SD increase in retinal venular caliber [β = -0.045 (-0.086 to -0.003), p = 0.036], and one SD increase in arteriolar branching angle [β = -0.039 (-0.072 to -0.006), p = 0.021]. Each SD increase in retinal tortuosity [β = -0.0075 (-0.0145 to –0.0004), p = 0.039] and each SD increase in arteriolar branching angle [β = -0.0073 (-0.0142 to –0.0059), p = 0.041] were also associated with decreased serum zeaxanthin.

Findings from the study provide initial evidence to support the link between serum levels of carotenoids lutein and zeaxanthin in healthy older adults and quantitative measures of retinal vascular parameters. Lower levels of carotenoid concentrations were found to be associated with features of retinal vasculature potentially reflective of structural vascular damage (e.g., narrow arteriolar caliber, wide arteriolar branching angle, etc.). Because of the cross-sectional nature of the study, a limitation of the current trial is its inability to establish a causal relationship between lutein and zeaxanthin and measures of retinal vasculature. Larger-scale prospective studies would be valuable to determine the underlying means by which carotenoids appear to support optimal retinal microcirculation.

Source: Kumari N, Cher J, Chua E, et al. Association of serum lutein and zeaxanthin with quantitative measures of retinal vascular parameters. PloS ONE. 2018; 13(9): e0203868.

© 2018 Kumari et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Click here to read the full text study.

Posted December 4, 2018.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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