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
Age-related macular degeneration can be detected in a routine eye exam. One of the most common early signs of macular degeneration is the presence of drusen -- tiny yellow deposits under the retina. Your doctor can see these when examining your eyes. Your doctor may also ask you to look at an Amsler grid -- a pattern of straight lines that resemble a checkerboard. Some of the straight lines may appear wavy to you, or you may notice that some of the lines are missing. These can be signs of macular...
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.