WEDNESDAY, Dec. 1 (HealthDay News) -- Eating a diet rich in omega-3 fatty acids appears to protect seniors against the onset of a serious eye disease known as age-related macular degeneration (AMD), a new analysis indicates.

"Our study corroborates earlier findings that eating omega-3-rich fish and shellfish may protect against advanced AMD," study lead author Sheila K. West, of the Wilmer Eye Institute at Johns Hopkins School of Medicine in Baltimore, said in a news release from the American Academy of Ophthalmology.

"While participants in all groups, including controls, averaged at least one serving of fish or shellfish per week, those who had advanced AMD were significantly less likely to consume high omega-3 fish and seafood," she added.

The observations are published in the December issue of Ophthalmology.

West and her colleagues based their findings on a fresh analysis of a one-year dietary survey conducted in the early 1990s. The poll involved nearly 2,400 seniors between the ages of 65 and 84 living in Maryland's Eastern Shore region, where fish and shellfish are eaten routinely.

After their food intake was assessed, participants underwent eye exams. About 450 had AMD, including 68 who had an advanced stage of the disease, which can lead to severe vision impairment or blindness.

In the United States, AMD is the major cause of blindness in whites, according to background information in the news release.

Prior evidence suggested that dietary zinc is similarly protective against AMD, so the researchers looked to see if zinc consumption from a diet of oysters and crabs reduced risk of AMD, but no such association was seen.

However, the study authors theorized that the low dietary zinc levels relative to zinc supplements could account for the absence of such a link.

Anand Swaroop, chief of the neurobiology, neuro-degeneration, and repair laboratory at the U.S. National Eye Institute, interpreted the findings with caution.

"It does make huge sense theoretically," he said. "Photoreceptors have a very high concentration of a specific type of fatty acids and lipids, relative to many other cell types. So it would make sense that omega-3 consumption would be beneficial. The theory is sound."

"However, I wouldn't want people to start taking grams of omega-3 to protect against AMD based on this finding because I'm not really sure that this study has sufficient power to draw any conclusions," Swaroop added. "This is just a one-year analysis and AMD is a long-term disease. The correlation is important, and it should be explored further. But we need larger studies with longer term follow-up before being able to properly assess the impact."

More information

For more on age-related macular degeneration, visit the U.S. National Eye Institute.