For people at a higher risk of macular degeneration as they age, eating sufficient levels of certain dietary nutrients could help protect their eyes.
A new study finds that among people with a genetic susceptibility to macular degeneration those who ate higher levels of zinc, antioxidants or omega-3 fatty acids cut their risk of developing the disease by as much as a third compared with those who ate lower levels of the nutrients.
"Therefore, clinicians should provide dietary advice to young susceptible individuals to postpone or prevent the vision-disabling consequences of (age-related macular degeneration)," the researchers wrote in the Archives of Ophthalmology.
At least two gene variations are known to raise a person's risk for developing the condition compared to the general population. One of the variations (called CFH) increases a person's odds of macular degeneration up to 11-fold and another (called LOC387715S) raises them by up to 15-fold.
To see whether these especially susceptible people might reduce their risk, the researchers, based in the Netherlands, surveyed the eating habits of more than 2,000 participants over the age of 55. All were tested for the macular degeneration susceptibility genes.
All the participants also had eye exams every three years for the next decade to determine who suffered vision loss.
Less risk of macular degeneration
Among people with the CFH variation, greater amounts of either zinc, beta carotene, omega-3 fatty acids or lutein/zeaxanthin in the diet was linked to a smaller risk of macular degeneration.
For instance, 39 out of every 100 people who ate the lowest amounts of omega-3 fats (about 22 mg per day) developed vision loss, whereas 28 out of every 100 people who ate the largest amounts of omega-3s (268 mg per day) had vision loss.
For those who had the LOC387715S variation, reduced risk of vision loss was seen among people who ate greater amounts of zinc or omega-3 fats.
In their case, for example, 25% of people who ate 11.85 mg per day of zinc developed macular degeneration, compared to 33% of people who ate just 7.5 mg per day.
"To achieve this benefit, it does not appear necessary to consume excessive amounts of these nutrients; the recommended dietary allowance will suffice," the authors note.
The recommended dietary allowance in the US for zinc is 11 milligrams daily for men and 8 milligrams for women. Men are recommended to consume at least 1.6 grams of omega-3 fatty acids a day, and women 1.1 grams.
The authors did not work out whether or how these nutrients are responsible for the prevention of macular degeneration.
(Reuters Health, Kerry Grens, June 2011)