Eating fatty fish reduces blindness risk from AMD: Study

By Dr. Ananya Mandal, MDMar 16 2011

New research has shown that consuming omega-3 fatty acids that are most commonly found in oily fish such as tinned salmon and tuna, could prevent the onset of age-related macular degeneration (AMD), a condition that leads to the gradual loss of vision. The required amount may be as low as one to two portions of fish a week that can reduce the risk of sight loss by up to 42 per cent in older women, according to a new study. Earlier results have shown similar benefits in men. Omega 3, whose common form in food is Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) can also be taken as a supplement.

According to lead author Dr William Christen, of Harvard Medical School, “dark meat” fish appeared to help the most. He explained, “This lower risk appeared to be due primarily to consumption of canned tuna fish and dark-meat fish.” Salmon, trout, and sardines are also loaded with omega-3 fatty acids. “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…Fish and fish oils may be of benefit in the primary prevention of AMD,” he added.

AMD affects more than 500,000 people in Britain. It is caused by the deterioration and death of the cells in the macula, a part of the retina used to see straight ahead. It commonly affects people over 40 and takes away their sight by creating a black spot in the centre of their vision which slowly gets bigger. With numbers of AMD sufferers expected to treble in the next 25 years as the population ages, there is an urgent need for a breakthrough. About 9 million Americans aged 40 and older show signs of AMD and 7.3 million more people have an early form of this potentially vision-robbing disease.

The team at Harvard Medical School included more than 38,000 women to obtain the findings. They gave questionnaires to assess participants eating habits, including how much omega-3 fatty acids each woman ate. These women were followed up for 10 years over which the women’s eye-health was tracked, with a specific focus on AMD. A total of 235 of the women who participated developed macular degeneration. On analysis it was noted that women who ate one or more servings of fish a week were two-fifths or 42% less likely to develop the condition than those who ate less than one serving of fish per month. The authors also found that the women who had the most omega 3 had a 38% lower risk of developing macular disease.

“In summary, these prospective data from a large population of women with no prior diagnosis of AMD indicate that regular consumption of DHA and EPA and fish significantly reduced the risk of incident AMD,” concluded the study which was published in the journal Archives of Ophthalmology.

The exact mechanism by which these fatty acids help in vision is still unclear. 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 Christen. More research is needed to confirm these findings, he says.

According to Jack Cohen, an ophthalmologist at Rush University Medical Center in Chicago, 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 adding, “Women with good fish or fatty acid intake may never get AMD.” However he said that other risk factors should be kept in mind. This includes smoking, family history of AMD, and high blood pressure.

Lylas G. Mogk, director of the Center for Vision Rehabilitation and Research at Henry Ford Health System in Detroit also lauded the study saying, “The article makes a very important contribution by providing clear evidence that omega-3 fatty acid intake can help prevent macular degeneration…We now know your risk is higher for AMD if you do not eat omega-3s.”