MONDAY, March 14 (HealthDay News) -- Women who consume fish regularly -- and the abundance of omega-3 fatty acids found in that meal choice -- have a lower risk of developing age-related macular degeneration (AMD), new research suggests.

This latest evidence of a protective link between fish oil and eye health mirrors past research that has found the same benefit. In this study, Harvard researchers performed a dietary analysis on more than 38,000 women.

"Our observational data needs to be confirmed in randomized trials," cautioned study author William G. Christen, an associate professor with the division of preventive medicine in the department of medicine at Brigham and Women's Hospital and Harvard Medical School in Boston.

"But already the message seems to be simple and strong," Christen added. "Fish oil, that is the omega-3 fatty acids found in fish, that have long been thought to be protective against cardiovascular disease may also be of significant benefit in the primary prevention of AMD among women who have no disease or have undetected early signs of disease, and have not yet been diagnosed with AMD."

Christen and his colleagues report on their research, which was funded partly by the U.S. National Institutes of Health, in the March 14 online edition of the Archives of Ophthalmology. The study will also appear in the June print issue of the journal.

The authors noted that about 9 million U.S. adults over the age of 40 have experienced some degree of AMD. Most have an early-stage form of the disease, while about 1.7 million have the advanced stage of illness that results in a serious loss of vision.

To date, there is no recognized method, aside from advising patients not to smoke cigarettes, to prevent or slow the onset of AMD among those who do not have the disease or only display the symptoms of early illness.

To explore how diet might function as a prevention tool, the investigators examined tens of thousands of food questionnaires completed by female health professionals who were enrolled in a heart disease and cancer prevention trial called the Women's Health Study.

No men were included in the study. All of the participants were in their 40s at the time of enrollment in 1993, and none had AMD at the study's start.

Eye health was also tracked over the course of a decade, during which time 235 women developed AMD.

The team observed that older women were more likely to consume higher amounts of both omega-3 fatty acids (which include docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), as well as omega-6 fatty acids (which include arachidonic acid and linoleic acid).

Those who consumed the greatest amount of one or both omega-3 fatty acids (DHA, EPA) were found to have a 38 percent lower risk of developing AMD compared with those women who consumed the least.

Specifically, women who ate one or more servings of fish every week had a 42 percent lower risk of AMD than those who consumed fish just once a month or less, the study found.

Most of the lower risk was linked to fish diets composed mainly of canned tuna and dark-meat fish, the researchers noted.

Although the authors uncovered a suggestion that higher consumption of one of the omega-6 fatty acids (linoleic acid) might actually boost the risk for AMD, that link was not deemed significant.

Christen and his associates concluded that their findings are "the strongest evidence to date" that omega-3 fatty acids protect against the onset of AMD.

Dr. David M. Kleinman, an associate professor and retina specialist with the Flaum Eye Institute at the University of Rochester in Rochester, N.Y., described the findings as "unsurprising, but very helpful."

"All scientists are going to say they need more research," he noted. "But this is great data, and it's supportive enough for me to already say to my patients, 'Eat fish. Or almonds.' Because realistically, we're talking about an intervention that has very little risk, and is something that we believe is really good for the eye."

More information

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