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NEW YORK (Reuters Life!) - Older adults who eat fatty fish at least once a week may have a lower risk of serious vision loss from age-related macular degeneration, according to a U.S. study.
The study by researchers at the Johns Hopkins University in Baltimore does not prove that eating fish cuts the risk of developing the advanced stages of age-related macular degeneration, or AMD.
But researcher Bonnielin K. Swenor said the findings add to evidence from previous studies showing that fish eaters tend to have lower rates of AMD than people who infrequently eat fish. They study, reported in the journal Ophthalmology (link.reuters.com/xut38m), also supports the theory that omega-3 fatty acids -- found most abundantly in oily fish like salmon, mackerel and albacore tuna -- may affect the development or progression of AMD.
"While the current research indicates that a diet rich in omega-3 fatty acids can reduce the risk of late AMD in some patients, more research is still necessary," Swenor told Reuters Health.
For the study, Swenor and her colleagues analyzed data from 2,520 adults aged 65 to 84 who underwent eye exams and completed detailed dietary questionnaires.
Fifteen percent were found to have early- or intermediate-stage AMD while just under 3 percent were in the advanced stage of the disease. Study participants who ate one or more servings of such fish each week were 60 percent less likely to have advanced AMD than those who averaged less than a serving per week.
Overall the researchers found there was no clear relationship between participants' reported fish intake and the risk of AMD but there was a connection between higher intake of omega-3-rich fish and the odds of advanced AMD.
AMD is caused by abnormal blood vessel growth behind the retina or breakdown of light-sensitive cells within the retina itself -- both of which can cause serious vision impairment. AMD is the leading cause of blindness in older adults.
There is no cure for AMD, but certain treatments may prevent or delay serious vision loss. A U.S. government clinical trial found that a specific high-dose mix of antioxidants -- vitamins C and E, beta- carotene and zinc -- can slow the progression of AMD that is in the intermediate stages, and doctors now commonly prescribe it for such patients.
Whether fish or omega-3 supplements can stall AMD progression is not yet clear but a follow-up to the U.S. antioxidant trial is now looking at whether adding fish oil and the antioxidants lutein and zeaxanthin to the original supplement regimen brings additional benefits.
Reporting by Amy Norton of Reuters Health, Editing by Belinda Goldsmith