Effects of Antioxidants and Fish Oil On AMD

New Nationwide Study Will Evaluate Effect Of Antioxidants And Fish Oil On Progression Of AMD

The National Institutes of Health (NIH) has announced a nationwide study to see if a modified combination of vitamins, minerals, and fish oil can further slow the progression of vision loss from AMD, the leading cause of vision loss in the United States for people over age 60. This new study, called the Age-Related Eye Disease Study 2 (AREDS2), will build upon results from the earlier Age-Related Eye Disease Study (AREDS). The original study results were released five years ago today. The study found that high-dose antioxidant vitamins and minerals (vitamins C and E, beta-carotene, zinc, and copper), taken by mouth, reduced the risk of progression to advanced AMD by 25 percent, and the risk of moderate vision loss by 19 percent.

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AREDS2 will refine the findings of the original study by adding lutein and zeaxanthin (plant-derived yellow pigments that accumulate in the macula, the small area responsible for central vision near the center of the retina) and the omega-3 fatty acids DHA and EPA (derived from fish and vegetable oils) to the study formulation. The main study objective is to determine if these nutrients will decrease a person's risk of progression to advanced AMD, which often leads to vision loss. Previous observational studies have suggested these nutrients may protect vision.

"Vision loss from AMD is an important public health issue. This study may help us find a better way to treat this devastating disease," said Elias A. Zerhouni, M.D., director of the NIH.

AMD damages the macula. As the disease progresses, it blurs the patient's central vision. AMD can take two forms, wet and dry. Wet AMD is caused by the abnormal growth of blood vessels under the macula. This leads to rapid loss of central vision. Wet AMD is considered to be advanced AMD and is more severe than the dry form. Dry AMD, the more common form, occurs when the light-sensitive cells in the macula slowly break down. Untreated dry AMD can progress into wet AMD.

Paul A. Sieving, M.D., Ph.D., director of the National Eye Institute (NEI) at NIH, said, "Nearly two million Americans have vision loss from advanced AMD, and another seven million with AMD are at substantial risk for vision loss. In the AREDS study, we found a combination of vitamins and minerals that effectively slowed the progression of AMD for some people. Now, we will conduct this more precisely-targeted study to see if the new combination of nutrients can reduce AMD progression even further. This study may help people at high risk for advanced AMD maintain useful vision for a longer time."

Emily Y. Chew, M.D., study chair and deputy director of the Division of Epidemiology and Clinical Research at the NEI said, "The AREDS2 study is seeking 4,000 people between 50 and 85 years of age with AMD in both eyes, or advanced AMD in one eye. They must be available for yearly eye examinations for at least five years. Until we get the results from AREDS2, we encourage people with AMD to visit their eye care professional to see if they need to take the AREDS vitamin and mineral formulation. This alone could save more than 300,000 people from vision loss over the next five years."

Article from http://www.sciencedaily.com

Fish Oil and AMD

Fish Oil May Reduce Risk of AMD (Age Related Macular Degeneration)

Age-related macular degeneration (AMD) -- the leading cause of age-related vision loss -- is nearly twice as common in elderly smokers as nonsmokers.

Seniors who eat fish at least twice weekly are almost half as likely to have AMD than those who eat fish less than once a week.

So say Johanna Seddon, MD, and colleagues in July's Archives of Ophthalmology. Seddon works at the Massachusetts Eye and Ear Infirmary, which is affiliated with Harvard Medical School in Boston.

Other experts in Australia 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.

Fish Oil and AMD - U.S. Study

Seddon's team studied data from 681 individual male twins in their mid-70s who were World War II veterans. The group included 222 men with intermediate- or late-stage AMD and 459 with early or no AMD.

The men completed questionnaires about their smoking history, alcohol use, physical activity, diets, and use of multivitamins and supplements.

"Current smokers had a 1.9-fold increased risk of AMD while past smokers had about a 1.7-fold increased risk" of AMD, compared with nonsmokers, the researchers write.

The study also shows that men with the highest fish consumption (at least two weekly servings) were 45% less likely to have AMD than those with the lowest fish consumption (less than one weekly serving).

Fish Oil and AMD - Australian Study

The Australian researchers included Brian Chua, BSc, MBBS, MPH, of the University of Sydney's ophthalmology department.

Chua and colleagues studied nearly 2,900 people aged 49 and older (average age: 63-65 years). Participants completed dietary questionnaires; five years later, they got special photographs of their retinas to screen for AMD.

Participants who reported eating at least one weekly serving of fish were 40% less likely to develop early-stage AMD during the study, compared with those who reported eating fish less than once a month or not at all.

People who ate fish frequently were also less likely to have late-stage AMD, the study shows. But that pattern was only seen in participants who reported eating fish at least three times weekly.

Fatty Acid Balance

When it comes to reducing AMD risk, striking the right fatty acid balance might be important, note Seddon and colleagues.

In their study, the reduced AMD risk was mainly seen in people who consumed high levels of omega-3 fatty acids and low levels of an omega-6 fatty acid called linoleic acid, which is found in vegetable oils including corn, safflower, and sunflower.

Seddon and colleagues aren't against omega-6 fatty acids. But they note that a lot of people consume way too much omega-6 fatty acids, compared with omega-3 fatty acids.
"The ideal omega-6/omega-3 ratio is 3:1 to 4:1," Seddon's team writes.

"However, the average American's diet has an omega-6/omega-3 ratio that ranges from 10:1 to 50:1 … Our results suggest that when our diet is rich in these omega-6 fatty acids (as measured here by linoleic acid), the protective effect of omega-3 fatty acids is dampened."

Chua's Australian study couldn't confirm those results.

Study's Limits

The studies don't prove that not smoking or eating fish prevented AMD.
Both studies were purely observational; participants weren't asked to quit smoking or change their diets. The studies also don't specify what type of fish participants ate, or how the fish was prepared.

Still, the results held after adjusting for other AMD risk factors.

Inflammation might partly explain the results, the researchers note. They point out that smoking boosts inflammation, while omega-3 fats reduce inflammation.

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This article was written by Mirandi Hitti at WebMd.com
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