Macular Xanthophylls and Their Effects on Vision
Lee Swanson Research Update
A substantial body of evidence suggests that the macular xanthophylls lutein and zeaxanthin have a protective effect against age-related macular degeneration (AMD), a neurodegenerative disease characterized by infiltration of blood vessels, leakage, inflammation and compromised vision.
Dr. Paul Bernstein, professor of ophthalmology and visual sciences at the University of Utah’s Moran Eye Center, discussed xanthophyll-binding proteins, which his lab identified as GSTP1, binding zeaxanthin and StARD3, binding lutein. A borderline association of GSTP1 variants has been correlated with a risk of AMD, and GSTP1 expression may be lower in AMD eyes, Bernstein explained. StARD proteins still need to be examined.
Bernstein’s ongoing research involves 53 Moran Eye Center patients who are participating in the national Age-Related Eye Disease Study 2 (AREDS 2). Continuing through 2012 or 2013, Bernstein’s study involves annual measurements of macular pigments, skin carotenoids and serum carotenoids. The current data suggests that skin and serum carotenoid measurements are not reliable biomarkers for macular pigment optical density. Notably, 70% of Bernstein’s subjects had high baseline levels of lutein and zeaxanthin; many reported taking supplements for years before the study. This may be due to their location: Utah is known as the "Silicon Valley" of nutritional supplements and accounts for one-fifth of all dietary supplement production in the United States, according to a February 2011 report published in Westlaw Business Currents.
Dr. John Paul SanGovanni, a co-director of AREDS 2, underscored the importance of large-scale genotypic projects in the field, referring to work in Bernstein’s lab and elsewhere. While the gene studies may not lead directly to clinical applications, taking the data in the context of the known relationship between macular xanthophylls and AMD can lead to new approaches in the study of macular xanthophylls and their metabolites in humans.
Current macular xanthophyll research isn’t limited to diseased eyes. Dr. B. Randy Hammond, principle investigator of the Vision Sciences Laboratory at the University of Georgia, discussed his ongoing research into the effects of lutein and zeaxanthin supplementation on healthy vision. His data suggests that supplementation of lutein and zeaxanthin does improve a person’s ability to withstand glare and recover quickly from a blinding flash of light.
Evidence also exists suggesting neuroprotective effects of lutein and, possibly to a lesser extent, zeaxanthin. Dr. Elizabeth Johnson, a research scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging, reviewed some of the evidence to date. Johnson’s recent research examines whether macular pigment density can be used as a biomarker for brain levels of lutein and zeaxanthin. The data does suggest a correlation between the pigment levels in the retina and various parts of the brain.
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March 2011