New research has found that a diet which is low in trans fats and regularly includes nuts, olive oil and other foods containing omega-three fatty acids appears to offer some protection from the eye disease age-related macular degeneration (AMD).
According to two new reports by researchers in Australia AMD is the leading cause of severe vision loss among individuals older than 65 in the developed world and established risk factors include age, genetic markers and smoking which is the only consistently reported modifiable risk factor.
It is estimated that by the year 2020, as many as 3 million Americans will have late-stage age-related macular degeneration (AMD).
One study led by Jennifer S.L. Tan, M.B.B.S., B.E., of Westmead Hospital in Sydney, Australia, involved 2,454 participants in the Blue Mountains Eye Study, which began in 1992 to 1994.
At that time, participants completed a food frequency questionnaire that was analysed to determine their intake of various fatty acids and digital photographs of their retinas were used to assess the development of AMD five and 10 years later.
The researchers found after adjusting for age, sex and smoking, eating one serving of fish per week was associated with a 31% lower risk of developing early AMD and the link was stronger among individuals with a lower intake of linoleic acid, an unsaturated omega-6 fatty acid found primarily in vegetable oils.
Eating one to two servings of nuts per week was associated with a 35% lower risk of early AMD.
The researchers say their findings support the hypothesis that increased intake of omega-three polyunsaturated fatty acids and regular consumption of fish and/or nuts in the diet may protect against the development of early AMD.
It is thought that the fatty acids may protect the eyes by preventing the build-up of plaque in the arteries or reducing inflammation, blood vessel formation and oxygen-related cell damage in the retina.
In other research by Dr. Elaine W.T. Chong from the Centre for Eye Research Australia, data from 6,734 individuals age 58 to 69 was analysed for a period between 1990 and 1994, when the participants' nutrient intakes were assessed from a food frequency questionnaire, and they were tracked for the development of AMD between 2003 and 2006.
During the follow-up period, 2,872 cases of early AMD and 88 cases of late AMD developed and the researchers say individuals who consumed higher levels of trans-unsaturated fats - found in baked goods and processed foods - were more likely to have late AMD, whereas those who consumed the most omega-three fatty acids were less likely to have early AMD.
Research has shown that trans-fats increase the risk of coronary heart disease through their effects on cholesterol levels and possibly through inflammation, whereas omega-three fatty acids are believed to protect against damage to the retina, thereby reducing risk for AMD.
The researchers say their findings suggest that people who follow a diet low in trans-fats and rich in omega-three fatty acids and olive oil might enjoy some protection from developing AMD.