March 14, 2011 -- Eating fatty fish one or more times a week may reduce your risk for developing age-related macular degeneration, a leading cause of vision loss in people aged 60 and older.
The new findings appear online in the Archives of Opthalmology.
About 9 million Americans aged 40 and older show signs of age-related macular degeneration (AMD) and 7.3 million more people have an early form of this potentially vision-robbing disease.
AMD targets the part of the eye that allows you to focus in on details (the macula). The disease destroys the sharp, central vision needed to see objects clearly, read, and drive. In some people the disease progresses slowly; in others, a faster progression can lead to vision loss in both eyes.
Women in the new study who got the highest amounts of docosahexaenoic acid (DHA), an omega-3 fatty acid found in fish, were 38% less likely to develop AMD than women who got the least DHA. Similar findings were seen regarding the highest consumption levels of eicosapentaenoic acid (EPA), another omega-3 found in fatty fish.
What’s more, women who ate one or more servings of fatty fish per week -- mainly canned tuna and dark-meat fish -- were 42% less likely to be diagnosed with AMD compared with women who ate fish less than once a month.
Salmon, trout, and sardines are also loaded with omega-3 fatty acids.
Role of Inflammation in AMD
Exactly how fatty fish and omega-3s may help reduce risk for AMD is not fully understood. But some research suggests that chronic inflammation may play a role in causing AMD. “Omega-3 fish oils are believed to have anti-inflammatory properties, so it’s plausible that these anti-inflammatory properties could be of benefit,” says study researcher William G. Christen, ScD, an associate professor of medicine at Brigham and Women’s Hospital and Harvard Medical School in Boston.
Using data from the Women’s Health Study, researchers analyzed the diets of 38,022 women with an average age of 54 who had not been diagnosed with AMD. During 10 years of follow-up, there were 235 cases of AMD reported.
“Among those people who really don’t have much AMD to begin with, the omega-3 fatty acids DHA and EPA and fish intake may help prevent future development of AMD,” Christen says. “Fish and fish oils may be of benefit in the primary prevention of AMD.”
More research is needed to confirm these findings, he says.
AMD Prevention
Jack Cohen, MD, an ophthalmologist at Rush University Medical Center in Chicago, says that if omega-3 fatty acids could prevent AMD from occurring it would be “amazing.”
The new study “does show potential for prevention and that is where AMD research is the weakest,” he says.
This will be a great breakthrough, if it is true,” says Cohen, who is an ophthalmologist in private practice at Illinois Retina Associates in Chicago. “Women with good fish or fatty acid intake may never get AMD.”
Other risk factors for AMD -- including smoking, family history of AMD, and high blood pressure -- should also not be overlooked, he says.
“If a patient had no macular degeneration, I would tell them that an omega-3 fatty acid intake may be of some benefit down the line,” he says. “A serving of fish per week would be wonderful for people without AMD, and if they had some signs of AMD already, there is no harm in adding a serving or fish per week or DHA supplements.”
"The article makes a very important contribution by providing clear evidence that omega-3 fatty acid intake can help prevent macular degeneration," says Lylas G. Mogk, MD, director of the Center for Vision Rehabilitation and Research at Henry Ford Health System in Detroit.
"We now know your risk is higher for AMD if you do not eat omega-3s," Mogk says.
While the study only looked at dietary sources of omega-3s, "if you don't eat a lot of fish or don't like fish, omega-3 supplements are a good idea," she says.