If you want lasting vision, eat your fish and nuts: The omega-3 fatty acids in these foods may protect against two leading causes of human blindness, a new study in mice has found.
The results showed omega-3s help regulate blood vessel growth in our eyes. That means the fatty acids could help prevent eye diseases such as retinopathy, caused by an overgrowth of leaky blood vessels in the eyes, and age-related macular degeneration, caused by abnormal growth of blood vessels, said study researcher Dr. Lois Smith, an ophthalmologist at Children's Hospital Boston.
The fatty acids also activated proteins that improve insulin sensitivity, Smith said. Those proteins are the same ones targeted by type 2 diabetes drugs such as Avandia, so the finding shows that fatty acids could be used to improve insulin sensitivity in people with diabetes, she said.
"Although more clinical studies need to be done, it appears possible that similar to mice, patients would have improved insulin sensitivity with omega-3 fatty acids, with no increased risk of heart disease," Smith told MyHealthNewsDaily.
To get the same beneficial health effects as the mice in the study, humans would have to consume 2 grams a day of omega-3 compounds docosahexaenoic acid (DHA) and eicosapentaenoic acid (EHA), either as a supplement or in food, she said.
The study was published Feb. 9 in the journal Science Translational Medicine.
Aspirin and fatty acids
Researchers also found that aspirin doesn't counteract the protective effects of omega-3 fatty acids.
This finding is especially important because aspirin is a good treatment for heart disease, and heart disease is a risk factor for macular degeneration, said Dr. Mina Chung, an associate professor of ophthalmology at the University of Rochester Medical Center in New York, who was not involved with the study.
If aspirin negated the effects of omega-3 fatty acids, patients would have to choose eye health over their heart health, Chung said.
There are few known ways to prevent retinopathy and macular degeneration, Chung said. Patients seek help only after the onset of the diseases.
"Most of the treatments for a lot of eye diseases are medications and surgeries and injections that are more costly," Chung told MyHealthNewsDaily. "But when you're looking at something that's so common, like those two diseases, if you can do something that's more preventive that's dietary, that would be huge."
A study published last month in the journal Archives of Ophthalmology reported that 6.5 percent of all Americans have age-related macular degeneration. Diabetic retinopathy is the cause of 12,000 to 24,000 cases of blindness each year, according to the National Institute of Diabetes and Digestive and Kidney Diseases.
The impact of omega-3s
Previous research has showed that people who eat more fish and omega-3 fatty acids are less likely to develop eye diseases than people who don't eat fish. A 2007 study by Smith, published in the journal Nature Medicine, showed that mice fed diets rich in omega-3s had 50 percent less blood vessel growth in their eyes than mice fed diets rich in omega-6 fatty acids (which are found in meat).
The new finding is important as the world's population ages, Chung said. Medical advances for heart disease and cancer increase our lifespan, but in tandem, age-related eye diseases are becoming more common, she said.
"People are living longer — so that's good — but as a result, we need to work on quality of life now," Chung said.
Smith and researchers from the National Eye Institute are now conducting a trial, called AREDS2, of omega-3 supplements in people with age-related macular degeneration, which will continue until 2013. The previous trial, AREDS1, found that people who ate a lot of fish were less likely to have age-related macular degeneration than people who didn't eat fish.
Smith is also working with researchers in Sweden to see if omega-3 fatty acids can prevent the retinopathy that sometimes develops in premature infants.
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