by Tom Hoglund, Information Officer
Foundation Fighting Blindness
Reprinted by permission from the Foundation Fighting Blindness.
Updated March 18, 2007
Patients with advanced cases of dry age-related macular degeneration (AMD) can moderately lower the risk of developing the more severe wet form of the disease and preserve vision by taking a daily dose of antioxidant vitamins and zinc. This finding is the result of the Age-Related Eye Disease Study (AREDS), a randomized, placebo-controlled clinical trial funded by the National Eye Institute. AREDS evaluated over 3600 men and women between the ages of 55 and 80 for an average of 6.3 years. Published in the October issue of the Archives of Ophthalmology, AREDS also evaluated whether antioxidants and zinc might reduce cataract development but found no beneficial effect.
Dr. Paul Sieving, Director of the National Eye Institute, stated, "Now that we know antioxidants and zinc are helpful in reducing the risk of severe disease, it is even more important for older-age Americans to have regular eye exams. Intervening in at-risk individuals could help reduce severe disease and vision loss in millions of Americans."
Specifically, the AREDS study found that AMD patients with advanced cases of dry AMD or vision loss due to wet AMD in one eye, who took daily supplements containing vitamin C, vitamin E, beta carotene, and zinc, had a 20% chance of developing wet macular degeneration over a five-year period. By comparison, the control group taking a placebo pill lacking any nutrients had a 28% chance of developing wet macular degeneration over a five-year period. This finding is important because delaying the onset of wet AMD and its accompanying vision loss by several years can prolong the independence and mobility of seniors and preserve their quality of life.
Dosages
Various vitamin companies are now manufacturing a supplement of antioxidants and zinc containing the dosages used in the AREDS study (see links below), or patients can purchase each nutrient separately. The daily therapeutic dosages of each of the nutrients used in the AREDS study are as follows: vitamin C, 500 mg; vitamin E, 400 IU; beta carotene, 15 mg; and zinc, 80 mg
Contraindications
Cancer prevention studies have found that high doses of beta carotene increase the risk of developing lung cancer in cigarette smokers. These studies strongly suggest that cigarette smokers, or those with smoking histories, should avoid taking beta carotene to prevent advanced macular degeneration.
The AREDS study findings are specific to patients with advanced cases of dry macular degeneration or vision loss from wet AMD in one eye. The study did not evaluate patients with early onset forms of macular degeneration such as Stargardt and Best disease. Due to the nature of the severe genetic defects that cause these early onset forms of macular degeneration, there is no evidence to support the use of high doses of antioxidants and zinc. There is also no evidence that antioxidants and zinc would offer benefit to patients with other retinal degenerative diseases such as retinitis pigmentosa. To the contrary, a well-designed clinical trial found that a daily dose of 400 IU of vitamin E resulted in a faster progression of vision loss for patients with common forms of retinitis pigmentosa.
Lutein and Zeaxanthin
Lutein and zeaxanthin are two antioxidant nutrients found highly concentrated in the macula. They give the macula its characteristic yellow appearance. Lutein and zeaxanthin are thought to protect the macula from oxidative stress due to light exposure. Because lutein and zeaxanthin supplements were not available at the start of the AREDS study, these nutrients could not be included. Future clinical trials will need to evaluate these antioxidants in AMD.
Am I Candidate For This Treatment?
Only a trained [eye care professional] can determine whether you have AMD and would be a candidate to begin antioxidant and zinc therapy. The Foundation Fighting Blindness and the National Eye Institute strongly urge adults over age 55 to have regular eye exams.
UPDATE: AREDS2
The National Eye Institute is recruiting 4,000 people with AMD for the second Age-Related Eye Disease Study (AREDS2). This is a followup to the original study described above.
This time, subjects will be given a slightly altered formula containing vitamins, minerals, lutein, zeaxanthin and omega-3 fatty acids DHA and EPA. The purpose is to see if the supplements help slow the progression of AMD to the advanced stages. For a list of study centers, eligibility requirements and other information, go to http://www.nei.nih.gov/AREDS2, or call 1-877-AREDS-80 (1-877-273-3780).
UPDATE: Beta-carotene and zinc
Since this article was written by Mr. Hoglund, two of the AREDS-recommended supplements have come into question. Beta-carotene has been shown in one study to have no effect on retinal health (click this link). Also, BBC News announced on March 18 that researchers at London's Institute of Ophthalmology think zinc may play a role in the development of AMD. For more information, click here).
Here are links to sources for dietary supplements which satisfy the dosages of antioxidants and zinc recommended by the first AREDS study. These companies offer several variations of the formula for differing needs, including lower levels of zinc, elimination of beta-carotene and addition of other ingredients thought to be beneficial to retinal health.
Vision-Nutrition.Com (Distributor of VisiVite, Ocuvite Preservision and ICaps AREDS Formula.)