Consuming a daily dose of 8 milligrams of zeaxanthin for one year produced an increase in MPOD in older men similar to that observed following 9 mg per day of lutein, according to findings published in Optometry.
In addition, zeaxanthin was associated with benefits to vision linked to cone cells in the retina, while lutein was associated with benefits to vision linked to rod cells.
“The remarkable increased visual acuity and heightened foveal shape discrimination with zeaxanthin potentially applies to sports vision (i.e. baseball players) and has military application (i.e. sharpshooters) for the young as well as old,” wrote researchers from the Captain James A. Lovell Federal Health Care Facility in Chicago and Rosalind Franklin University of Medicine and Science in Illinois.
Zeaxanthin
The macula is a yellow spot of about five millimeters diameter on the retina. As we age, levels of the pigments in the macula decrease naturally, thereby increasing the risk of age-related macular degeneration (AMD). The yellow color is due to the content of the carotenoids lutein and zeaxanthin, which we derive from the diet.
These compounds are the only carotenoids capable of filtering the harmful blue light than can damage cells in the eye, the rods and the cones.
A thin macular pigment can allow the blue light through and destroy the cells. Maintaining high levels of both carotenoids, and therefore the macular pigment, is a valid approach to maintaining eye health and reducing the risk of AMD.
Study details
The Illinois-based researchers recruited 60 people with an average age of 75 to participate in their randomized controlled clinical. All of the participants had mild-to-moderate AMD, and were considered lower-risk than those included in the National Institute of Health/National Eye Institute/Age-Related Eye Disease Study.
Participants were randomly assigned to receive 8 mg per day of zeaxanthin (Chrysantis), or 8 mg zeaxanthin plus 9 mg lutein, or 9 mg lutein for one year.
All three supplementation programs increased MPOD, and there were no differences between the groups.
Detailed high-contrast visual acuity improved in the zeaxanthin group, while low-contrast visual acuity was improved the most in the lutein only group.
“In older male patients with AMD, zeaxanthin -induced foveal MPOD elevation mirrored that of L and provided complementary distinct visual benefits by improving foveal cone-based visual parameters, whereas L enhanced those parameters associated with gross detailed rod-based vision, with considerable overlap between the 2 carotenoids,” wrote the researchers.
“The equally dosed (atypical dietary ratio) zeaxanthin plus L group fared worse in terms of raising MPOD, presumably because of duodenal, hepatic-lipoprotein or retinal carotenoid competition.”
Source: Optometry - Journal of the American Optometric Association
November 2011, Volume 82, Issue 11, Pages 667-680.e6
Authors: S.P. Richer, W. Stiles, K. Graham-Hoffman, M. Levin, D. Ruskin, J. Wrobel, D-W. Park, C. Thomas