Fish, nuts and olive oil may cut age-related blindness risk

Studies from two different teams suggest that adding omega-3 fatty acids such fish, nuts and olive oil to a diet could help reduce the risk of a common eye disorder called age-related macular degeneration, or AMD.

This disorder is a disease of the macula, the part of the retina responsible for central vision, and a leading cause of vision loss in Americans 60 years of age and older.

The first research
To reach their findings, first research team headed by Jennifer S.L. Tan, M.B.B.S., B.E., of Westmead Hospital, University of Sydney, Australia, examined 2,454 men and women for up to a decade.

Tan and colleagues asked the study volunteers to keep food diaries giving details of their intake of various fatty acids for two years.

Tan’s research team found that people who ate one serving of fish per week were at 31 percent lower risk of developing early AMD than those who did not.

The team also found that eating a couple of servings of nuts per week lowered the risk by 35 percent.

"In conclusion, our 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," said Tan, who reported the findings in the May issue of Archives of Ophthalmology, one of the JAMA/Archives journals.

The second research
In the other study, Elaine W.T. Chong, M.D., Ph.D., M.Epi., of the Centre for Eye Research, Australia, and colleagues analyzed data from 6,734 individuals age 58 to 69.

Chong and colleagues assessed the participants' nutrient intakes from a food frequency questionnaire between 1990 and 1994, and followed them for the development of AMD between 2003 and 2006. During the follow-up period, at least 2,872 volunteers developed early AMD and 88 developed late AMD.

The team found that participants who consumed the highest amounts of omega-3 fatty acids were at 15 percent lower risk of early-stage AMD. People who consumed the most olive oil- 100 millilitres or about seven tablespoons a week- were about half as likely to develop late AMD as those who had less than 1 millilitre per week.

"Olive oil intake was associated with decreased prevalence of late AMD," Chong wrote. "No significant associations with AMD were observed for intakes of fish, total fat, butter or margarine."

Dr. Chong and her team also found that those who consumed the most trans fat, a type of fat often found in commercial baked goods and fried foods, were 1.76 times more likely to develop late AMD. Trans fat is known to boost low-density lipoprotein (LDL) or "bad" cholesterol.

"Our findings suggest that people who follow a diet low in processed foods high in trans-unsaturated fatty acids and rich in omega-three fatty acids and olive oil might enjoy some protection from developing AMD," Chong concluded.

Chong’s findings also appear in the Archives of Ophthalmology.

About age-related macular degeneration
Age-related macular degeneration or AMD is a major cause of blindness in people aged 65 and older. The disease is associated with aging that gradually destroys sharp, central vision, needed to read or drive.

AMD affects the macula, the part of the eye that allows an individual to see fine details, and it occurs in two forms: wet and dry.