Forget which came first. Turns out that the venerable egg, not the chicken that hatched it, may actually help prevent one of the nation's most common forms of blindness in people over 55.
According to research from the University of Massachusetts Lowell and the University of New Hampshire, regular consumption of eggs -- scrambled, hard-boiled, over easy -- may help stave off macular degeneration, the leading cause of blindness among seniors.
Scientists found that egg yolks -- long reviled for their cholesterol-packing punch -- contain two carotenoids, or pigments, that, when entering the bloodstream, are believed to create a protective density in the eye that may actually help preserve one's baby blues.
"The hypothesis is that if people eat more eggs, the higher the blood levels of carotenoids, which should translate in greater macular pigment concentrations," said Robert Nicolosi, a nutritional biochemist at UMass Lowell and one of the study's lead researchers. "The egg yolk is a great way of delivering these kinds of nutrients. And if more gets into the bloodstream, more gets into eye, and the eye is where you want these nutrients. There's even some evidence it can reduce the incidence of cataracts."
Previous studies done by Harvard Medical School and Schepens Eye Research Institute on Japanese quails confirmed that the presence of two specific carotenoids in the bloodstream -- lutein and zeaxanthin -- help protect the retina from light damage.
While separate studies have focused on carotenoid supplements in pill form, the UMass Lowell and UNH researchers say they are the first to examine how a natural supply of the carotenoids -- as found in eggs -- might prove a better, more natural option for those looking to prevent the onset of macular degeneration.
"One egg a day gave a 25 to 30 percent increase in bloodstream of the antioxidants lutein and zeaxanthin," Nicolosi said. "If one egg does that, what do two, three or four do?"
As the eye ages, photoreceptors irreversibly die and are replaced with leaky, unwanted blood vessels that limit the field of vision. In its advanced stages, macular degeneration can make everyday activities like reading, driving or recognizing even familiar faces impossible. And while several new drugs have emerged recently to treat the wet form of macular degeneration, those cases account for just 10 percent of all cases of AMD.
According to the Macular Degeneration Research Fund, 17 million Americans suffer from the disease, 2 million are functionally blind, and an additional 500,000 of AMD cases are diagnosed each year.
During the first of the team's early studies, the UMass Lowell/UNH team gave seven subjects six eggs per week and six other subjects a placebo, then measured their macular pigment optical density for the presence of lutein and zeaxanthin. Those who'd consumed eggs showed significant increases in their serum lutein and zeaxanthin levels. The scientists also found that consuming six eggs a week provided an effective source of the carotenoids without adversely affecting cholesterol levels among healthy subjects.
In a second arm, researchers reported on 11 subjects ages 65 and older who first abstained from egg consumption for a month, then ate an egg a day for five weeks before repeating the cycle again. Again, the researchers found that an egg a day did not adversely elevate cholesterol but did impact the plasma levels of both lutein and zeaxanthin by 27 and 66 percent, respectively.
But even the researchers say it's still too early to make a sound prediction about eggs' impact on eye health. And those familiar with the link between carotenoids and ophthalmology remain skeptical about the study until a larger sample size is documented and the report is officially published.
Alice Adler, a carotenoid biochemist affiliated with Harvard University expressed interest in the report but wanted to reserve judgment until after the research was published.
"It's been known for quite some time that eggs have lots of lutein and zeaxanthin, and that's been known to help prevent age-related AMD," Adler said. "But unless they can show this is heart-healthy, I'll have to wait."
The research team is recruiting volunteers for the next stage of the study -- which will take place over five years -- that will administer between two and four eggs a day to a crop of at least 68 subjects, all of whom are on cholesterol-lowering drugs called statins. The researchers will then break down the group by age and eye health.
While the UMass Lowell/UNH team members are guarded about the study's outcome, Nashua ophthalmologist John Dagianis, affiliated with Nashua Eye Associates, already advises patients to regularly consume eggs on a modest scale. And while Dagianis maintains it's too early to draw definitive conclusions, he calls the possibility of a natural remedy to macular degeneration "huge."
"We don't really have a lot to offer (those suffering from macular degeneration) now that is specific nutrient directive," Dagianis said. "There are other studies going on to see if taking vitamins can make a difference, but we're trying to see if there's more to the story than just taking those vitamins. What we're trying to do is say, is there something more?"