The link between lutein and eye health was first reported in 1994 by Dr Johanna Seddon and her co-workers at Harvard University, who found a link between the intake of carotenoid-rich food, particularly dark green leafy vegetables like spinach, and a significant reduction in AMD (JAMA, Vol. 272, pp. 1413-1420).
Lutein and zeaxanthin are the only carotenoids capable of filtering the harmful blue light than can damage cells in the eye, the rods and the cones.
The carotenoids are concentrated in the macula, a yellow spot of about five millimeters diameter on the retina. A thin macular pigment can allow the blue light through and destroy the cells. According to a 2010 review published in Vision Research (Vol. 50, pp 716-728) macular pigment optical density (MPOD) - an indicator of xanthophyll levels in the eye - may also “potentially serve as a biomarker not only for predicting the risk for eye disease but also for visual function”.
The new study, published in the British Journal of Ophthalmology, found that lutein and zeaxanthin could booth MPOD in people with early AMD, and also enhance retinal sensitivity/function.
“Improvement in retinal function as a result of macular pigment augmentation is probably attributable to at least one of two mechanisms,” wrote researchers from Peking University. “First, pre-receptoral filtration of blue light will attenuate the adverse effect of chromatic aberration and of veiling luminance on contrast sensitivity. Second, the antioxidant effect of macular carotenoids may exert a beneficial effect in maculae afflicted with conditions known to result from oxidative stress, such as AMD.”
Further confirms the importance of supplementation
The results were welcomed by leading lutein suppliers, including Kemin Health and OmniActive.
Lynda Doyle, vice president of global marketing at OmniActive, said: “It’s always good to see long-term research supporting the role of lutein and zeaxanthin in macular health. MPOD and retinal sensitivity improved from baseline in all groups.
“This study further confirms the importance of supplementing with macular carotenoids,” she added.
Dick Roberts, PhD, principal manager; scientific affairs & technical services for Kemin Human Nutrition and Health Division, welcomed the contribution of the researchers, Huang et al.
“This paper clearly indicates that supplementation with either lutein or lutein combined with zeaxanthin help improve visual functionality in subjects with early age-related macular degeneration (AMD) as measured by macular pigment optical density (MPOD), multifocal electroretinograms (mfERG) or microperimetry (MRS),” said Dr Roberts.
“The results are not surprising given the fact that functional improvements in vision with administration of similar amounts of FloraGLO Lutein have been shown in both young, healthy subjects1 as well as in subjects with more advanced AMD.
“However, the Huang, et al. study definitively showed that such benefits may potentially extend to include individuals with early AMD. This is highly important since early AMD represents a significant segment of the population in which fewer numbers of studies have been conducted.
“The results obtained showed that the most rapid change in MPOD values was seen in subjects taking either 20 mg of lutein or the combination of 10 mg of lutein + 10 mg zeaxanthin daily. Given the results obtained from the AREDS2 study which showed that daily supplementation with 10 mg of FloraGLO Lutein and 2 mg of OptiSharp Zeaxanthin helps reduce the risk of progression of AMD in subjects with later stages of AMD and helps improve visual function in healthy subjects from the same dosages of FloraGLO Lutein and OptiSharp Zeaxanthin, the results found by Huang, et al. indicate that the increases seen in MPOD, mfERG and MRS amongst early AMD subjects taking the highest daily dosage of lutein or the combination of lutein plus zeaxanthin results in deposition of these macular carotenoids into the macula of the eye. In that location these carotenoids should help improve visual performance and may even help reduce progression of AMD.”
Dr Roberts added that, even though the results from this study will need to be replicated and advanced with additional measures of ocular function and health, they do provide important data that are needed to advance the state of the art in helping reduce the risks for AMD, particularly early AMD.
“Regardless, the results of Huang et al. support the use of higher dose lutein supplementation to achieve more rapid deposition of lutein and zeaxanthin in the macula leading to enhanced visual functionality in individuals with early AMD,” he added.
The Peking-based scientists recruited 112 people with early AMD and randomly assigned them to one of four groups: Placebo, lutein supplements at a daily dose of 10 mg, lutein supplements at 20 mg per day, or lutein (10 mg) plus zeaxanthin (10 mg) for two years.
Results showed that lutein and zeaxanthin increased MPOD significantly in all of the active supplement groups, compared to placebo.
In addition, retinal function was found to increase significantly in the central retina, said the researchers.
“There is a growing body of evidence that supplementation with macular carotenoids may also increase MPOD and visual performance in normal subjects without macular diseases,” they wrote. “It is possible therefore that the implications of our findings may be clinically valuable for both AMD and normal subjects.
“In other words, macular pigment augmentation is likely to enhance visual performance and experience in the elderly by attenuating the deleterious effects of chromatic aberration and veiling luminance on contrast sensitivity, irrespective of macular disease status (as long as the condition is not in its advanced form). Such optimization of vision is clinically important for vulnerable older adults, as it will render daily activities, such as driving, easier and safer.”
Source: British Journal of Ophthalmology
Volume 99, Pages 371-375, doi:10.1136/bjophthalmol-2014-305503
“Changes following supplementation with lutein and zeaxanthin in retinal function in eyes with early age-related macular degeneration: a randomised, double-blind, placebo-controlled trial”
Authors: Y-M. Huang, H-L. Dou, F-F. Huang, et al.