Whereas the smoking increases the risk of the most common cause of blindness among the elderly, eating fish frequently protects against it, U.S. and Australian researchers have found in two recent studies.
The novel studies indicate that eating fish regularly and not smoking may significantly reduce the risk of developing age-related macular degeneration (AMD).
One study published in July’s Archives of Ophthalmology analysed data from 681 World War II male twins in their 70s. The group consisted of 222 men with intermediate- or late-stage AMD and 459 men with early or no AMD. Researchers had the men fill out questionnaires on their history of smoking and alcohol use, as well as their diet, physical activity and use of vitamins and supplements.
The researchers from the Massachusetts Eye and Ear Infirmary, affiliated with Harvard Medical School in Boston, found that current smokers had a 1.9-fold greater risk of developing AMD, while past smokers increased their risk 1.7-fold, compared to nonsmokers. There was also a higher risk for those who had smoked in the past but quit.
The Boston study also found that those who ate the maximum number of fish, including those who smoked, were less likely to have developed the disease, with the biggest benefit among those who ate two or more servings per week. Such persons reduced their risk of AMD by 45 percent over those who had less than one weekly serving.
In Australia, researchers at the University of Sydney, who also recently completed a five-year study of 2,900 people 49 and older, found that age-related macular problems are rarer in people whose diets are rich in omega-3 fatty acids, which are found in fish, including salmon and mackerel, as well as flax seeds and walnuts. Such people reduced their risk of developing AMD by 40 percent.
Dr. Johanna Seddon, the lead author of the Boston -based study, stressed the importance of not only getting enough omega-3 fatty acids, but also properly balancing the amounts of omega-3s with omega-6 fatty acids.
“The ideal omega-6/omega-3 ratio is 3:1 to 4:1,” Seddonalong with his team wrote in the study. “However, the average American’s diet has an omega-6/omega-3 ratio that ranges from 10:1 to 50:1.” Seddon says over-eating omega-6 fatty acids, found in oils from corn, safflower and sunflower, lessens the protective effects of omega-3s.