For example, the Age-Related Eye Disease Study (AREDS) is a major research effort by the U.S. National Eye Institute. The first AREDS study found that supplementing your diet with high levels of vitamins C, E, and beta-carotene, called antioxidants, and the mineral zinc may help slow the progress of advanced age-related macular degeneration (AMD) and delay vision loss if you already have moderate or severe AMD. There is no evidence that the supplements are helpful if you do not have AMD or only have a mild form of the disease.1
Your ophthalmologist or optometrist will inspect the macula, the portion of the retina that is responsible for your central vision, as part of a comprehensive eye exam. If macular degeneration is suspected, a special photographic procedure using dye, called fluorescein angiography or another test called OCT imaging may be performed. The tests detail the pattern of your eye's blood vessels and retinal anatomy and can detect a variety of abnormalities.
The study showed the largest benefit for people who had already begun to develop AMD (intermediate AMD) in one or both eyes or who had advanced AMD in one eye. In these groups, the risk for advanced AMD or for AMD in the other eye was reduced by about 25%. The chance of developing vision loss from advanced AMD was reduced by about 20% in those taking the vitamins and zinc supplements.
Although there may be some benefit from taking the vitamins alone or the zinc alone, the greatest benefit was seen in those who took both.
The study did not find any significant benefit from the supplements in people who had only the early signs of AMD.
The study found that taking the supplements did not help improve vision already lost from AMD.
In a study of male doctors who didn't have AMD, researchers found that taking vitamins E and C for up to 8 years, either alone or in combination, was not likely to affect whether or not a person got early AMD. This finding is consistent with other studies that looked at preventing AMD by using vitamins.2
If you're interested in taking a vitamin or mineral supplement, talk with your doctor about the risks. For example:
Some can have harmful side effects or make certain health problems worse, especially in high doses.
People who smoke or who used to smoke should not take beta-carotene. Studies have shown a higher incidence of lung cancer in people who smoke and take beta-carotene.