September 11 , 2007

Lutein/zeaxanthin again linked to lower AMD risk

By Clarisse Douaud

11/09/2007 - Supplementing with lutein and zeaxanthin has once again been associated with a lower risk for age-related macular degeneration, according to a new report.

Published in the September issue of Archives of Ophthalmology, the research was undertaken as part of the Age-Related Eye Disease Study (AREDS) - a major clinical trial sponsored by the National Eye Institute under the umbrella of the National Institutes of Health. The AREDS Research Group assessed 4,519 participants between the ages of 60 to 80 years when they enrolled in 1992 through 1998.

The study's findings add further scientific weight to the potential for these carotenoids to stem a leading cause of blindness in people of European descent.

"Higher dietary intake of lutein/zeaxanthin was independently associated with decreased likelihood of having neovascular AMD, geographic atrophy, and large or extensive intermediate drusen," concluded the authors.

AMD is the leading cause of legal blindness for people over 55 years of age in the Western world, according to AMD Alliance International.

Despite the fact that approximately 25 to 30 million people worldwide are affected by AMD, awareness of the condition is low, according to AMD Alliance International. And as the generation of Baby Boomers gets older, the Alliance expects incidence to be on the rise and triple by 2025.

AMD is a degenerative retinal disease that causes central vision loss and leaves only peripheral vision. Early detection is cited as a means of prevention so that treatment or rehabilitation can be undertaken early enough. However, links to diet have also been underscored.

"A number of diet-based compounds concentrated in the retina may have the capacity to modulate exogenous and endogenous defense and repair systems in response to oxidative stress and inflammation," explained the researchers in the study.

This link between dietary nutrients and AMD has been investigated in numerous recent publications. The nutrients include lutein and zeaxanthin, omega-3 fatty acids, provitamin A carotenoids, vitamin A, retinol, alpha-tocopherol and vitamin C.

As part of this study, the researchers looked at whether the dietary nutrient and AMD link does in fact exist when taking into consideration the influence of nonnutritional factors such as demographic factors, medical history and treatment history.

At the time of the clinical trial, photographs were taken of the participants' retinas to determine if they had AMD and to which of four stages the condition had progressed. The participants filled out a food frequency questionnaire measuring how often they consumed foods rich in certain vitamins, minerals and other nutrients.

Dietary lutein/zeaxanthin intake was inversely associated with neovascular AMD with an odds ratio of 0.64; 95 percent confidence interval [CI], 0.45-0.93, when comparing the highest versus lowest quintiles of intake, after adjustment for total energy intake and non-nutrient-based covariates.

"If these cross-sectional results can be confirmed in prospective samples and experimental studies, lutein and zeaxanthin may be considered as useful agents in food or supplement-based interventions designed to reduce the risk of AMD," wrote the researchers.

Previous studies have also reported a link between AMD and lutein and zeaxanthin, found in leafy green vegetables, corn, egg yolks, squash, broccoli and peas. The carotenoids are proposed to reduce the risk of AMD by absorbing blue light that could damage the macula, by preventing free radicals from damaging eye cells and by strengthening eye cell membranes.

Source:

"The Relationship of Dietary Carotenoid and Vitamin A, E, and C Intake With Age-Related Macular Degeneration in a Case-Control Study: AREDS Report No. 22 Age-Related Eye Disease Study Research Group." Arch Ophthalmol. 2007;125:1225-1232.

Source: www.nutraingredients.com