Report on a Study: Dietary Supplements Reduce Risk of Vision Loss from Age-Related Macular Degeneration, Same Supplements Have No Effect on the Development of Cataracts.
A dietary supplement of high levels of antioxidants and zinc significantly reduces the risk of advanced age-related macular degeneration (AMD) and its associated vision loss. These same supplements had no significant effect on the development or progression of cataract. These findings from a nationwide clinical trial are reported in the October 2001 issue of Archives of Ophthalmology. The Massachusetts Eye and Ear Infirmary in Boston was the only center in New England involved in this study.
Scientists found that people at high risk of developing advanced stages of AMD, a leading cause of vision loss, lowered their risk by about 25 percent when treated with a high-dose combination of vitamin C, vitamin E, beta-carotene, and zinc. In the same high risk group - which includes people with intermediate AMD, or advanced AMD in one eye but not the other eye - the supplements reduced the risk of vision loss caused by advanced AMD by about 19 percent. For those study participants who had either no AMD or early AMD, the supplements did not provide an apparent benefit. The clinical trial - called the Age-Related Eye Disease Study (AREDS) - was sponsored by the National Eye Institute (NEI), one of the Federal government's National Institutes of Health.
"This discovery is very exciting because these dietary supplements are the first effective treatment to slow the progression of the disease in people at high risk for developing advanced AMD," said Johanna M. Seddon, M.D., director of the AREDS study at the Massachusetts Eye and Ear Infirmary and author of several publications relating nutritional factors to age-related eye diseases. "Macular degeneration is the leading cause of blindness in older people and currently, treatment for advanced AMD is quite limited. These supplements will delay the progression to advanced AMD in people who are at high risk - those with intermediate AMD in one or both eyes, or those with advanced AMD in one eye already," Dr. Seddon added.
"The supplements are not a cure for AMD, nor will they restore vision already lost from the disease," said Paul A. Sieving, M.D., Ph.D., director of the NEI. "But they will play a key role in helping people at high risk for developing advanced AMD keep their vision."
A common feature of AMD is the presence of drusen, which are yellow deposits under the retina. Often found in people over age 60, drusen can be seen by an eye care professional during an eye exam in which the pupils are dilated. Drusen by themselves do not usually cause vision loss, but an increase in their size and/or number increases a person's risk of developing advanced AMD, which can cause serious vision loss.
The three stages of AMD analyzed in this study are:
These two forms of advanced AMD can cause serious vision loss. Scientists are unsure about how or why an increase in the size and/or number of drusen can sometimes lead to advanced AMD, which affects the sharp, central vision required for the 'straight ahead' activities in our daily routine, such as reading, driving, and recognizing faces of friends. One observation is that the larger and more numerous the drusen, the higher the risk of developing either form of advanced AMD. People who have advanced AMD in one eye are at especially high risk of developing advanced AMD in the other eye. The dietary supplements used in the study contained several antioxidant vitamins, which are nutrients that can help maintain healthy cells and tissues. They also contained zinc, which is an important mineral incorporated into many body tissues.
The supplements evaluated by the AREDS researchers contained:
In this trial, the NEI collaborated with Bausch and Lomb, an eye care company that provided the supplements evaluated by the AREDS researchers and financially supported the laboratory testing and distribution of study medications. Previous studies have suggested that people who have diets rich in green, leafy vegetables have a lower risk of developing AMD. One of these studies was conducted by Dr. Seddon at the Massachusetts Eye and Ear Infirmary and published in 1994 in the Journal of the American Medical Association. "However, the high levels of dietary supplements that were evaluated in the AREDS are very difficult to achieve from diet alone," said Frederick Ferris, MD, director of clinical research at the NEI and chairman of the AREDS.
"Almost two-thirds of AREDS participants chose to take a daily multivitamin in addition to their assigned study treatment. The AREDS also showed that, even with a daily multivitamin, people at high risk for developing advanced AMD can lower the risk of vision loss by adding a dietary supplement with the same high levels of antioxidants and zinc used in the study."
The Age-Related Eye Disease Study involved 4,757 participants, 55-80 years of age, in 11 clinical centers nationwide. The Massachusetts Eye and Ear Infirmary enrolled 517 people in the study and had the largest patient base recruited. Participants in the study were given one of four treatments: 1) zinc alone; 2) antioxidants alone; 3) a combination of antioxidants and zinc; or 4) a placebo, a harmless substance that has no medical effect. The benefits of the dietary supplements were seen only in people who began the study at high risk for developing advanced AMD - those with intermediate AMD, and those with advanced AMD in one eye only. In this group, those taking "antioxidants plus zinc" had the lowest risk of developing advanced stages of AMD and its accompanying visual loss. Those in the "zinc alone" or "antioxidant alone" groups also reduced their risk of developing advanced AMD, but at more moderate rates compared to the "antioxidants plus zinc" group. Those in the placebo group had the highest risk of developing advanced AMD.
Dr. Ferris said some people with intermediate AMD may not wish to take large doses of antioxidant supplements or zinc because of medical reasons. "For example, beta-carotene has been shown to increase the risk of lung cancer among smokers," he said. "These people may want to discuss with their primary care doctor the best combination of supplements for them. With any supplements containing zinc, it is important to add appropriate amounts of copper to the diet to prevent copper deficiency."
In the cataract portion of the study, researchers discovered that the same supplements had no significant effect on the development or progression of age-related cataract. A cataract is a clouding of the eye's lens that blocks some light from reaching the retina and interferes with vision. "Participants taking the 'zinc alone' treatment, the 'antioxidants alone' treatment, or the combination of zinc and antioxidants were all about as likely to develop a cataract as those taking a placebo," Dr. Ferris said.
"At the time the study was planned, laboratory and animal research had suggested that antioxidants might be of benefit in treating or preventing cataract," he said. "Also at that time, limited epidemiologic and clinical trial data suggested that antioxidants might affect the development of cataract. However, our analyses did not find any connection between the antioxidant supplements used in the AREDS and cataract development."
Despite the evidence that these supplements did not lower the risk of cataract development over the seven-year period of the study, Dr. Ferris noted that an effect over a longer period of time, or with different doses of these or other antioxidants, cannot be ruled out.
The AREDS participants reported minor side effects from the treatments. About 7.5 percent of participants assigned to the zinc treatments - compared with five percent who did not have zinc in their assigned treatment - had urinary tract and prostate problems that required hospitalization. Participants in the two groups that took zinc also reported anemia at a slightly higher rate; however, testing of all patients for this disorder showed no difference among treatment groups. Yellowing of the skin, a well-known side effect of large doses of beta-carotene, was reported slightly more often by participants taking antioxidants.
"The AREDS dietary supplements are the first demonstrated treatment for people at high risk for developing advanced AMD," he said. "Slowing the progression of AMD to its advanced stage will save the vision of many who would otherwise have had serious vision impairment."
People who should consider taking the supplements include those who are at high risk for developing advanced AMD. These people are defined as having either:
Your eye care professional can tell you if you have AMD - and its level of development - through an eye exam in which drops are placed in the eyes to dilate the pupils. This allows for a careful examination of the inside of the eye.
People with intermediate AMD in one or both eyes, or those with advanced AMD in one eye only, and who are advised to take dietary supplements like those used in the AREDS, should review the other supplements they are taking with their primary care doctors and/or eye care professionals. In addition to their study medication, most of the participants in the AREDS took a multivitamin that contained the approximate recommended dietary allowance of most vitamins and minerals.
Bausch and Lomb, an eye care company, was a collaborator in the AREDS and provided the study supplements. The company will market the formulation used in the AREDS; other companies will probably provide similar formulations. Antioxidant and zinc supplements can also be purchased separately; however, consumers should discuss the use of these high levels of supplements with their doctors, and be certain to include copper whenever taking high levels of zinc.
Bausch and Lomb will market only the "antioxidants plus zinc" formulation. Those who are advised by their primary care doctors to take the AREDS' "zinc alone" or "antioxidant alone" formulations, as well as those who choose to purchase the "antioxidants plus zinc" formulation from another manufacturer, should compare the labels of those products with the AREDS formulations. Antioxidant and zinc supplements can also be purchased separately; however, consumers should discuss the use of these high levels of supplements with their doctors, and be certain to include copper whenever taking high levels of zinc. Your primary care doctor can help you determine which formulation and dose is best for you.
They are manufactured by Bausch and Lomb and called Ocuvite® PreserVision™ . They can be found at many pharmacies, over-the-counter, throughout the U.S.
Yes. There are reasons to be cautious in using high-dose dietary supplements, particularly among older people. Many older Americans take prescription medications, and a considerable number use over-the-counter drugs, other dietary supplements, and herbal medicines. Dietary supplements of high-dose nutrients can interfere with medications and interact with other nutrients to decrease the nutrients' absorption into the body. This can ultimately affect a person's nutritional and health status. For example, the zinc concentration in the AREDS supplement is at a very high dose and could cause copper deficiency anemia. To prevent this, copper was added to the AREDS supplement. People who are being treated for chronic diseases such as cancer, heart disease, and diabetes should not take high dose supplements without talking with their doctors.
Generally, self-medication with high doses of vitamin and mineral supplements - such as those in the AREDS formulation - is not recommended. Individuals who are considering taking the AREDS supplements should discuss this with their primary care doctors and/or eye care professionals. They can help you determine which formulation and dosages are best for you.
There is no apparent need for those diagnosed with early AMD to take the supplements studied in the AREDS. This is because the study did not demonstrate that the supplements provided a benefit to those with early AMD. Many people with early AMD progressed to intermediate AMD during the study, and the AREDS supplements did not seem to slow this progression. However, if you have early AMD, a dilated eye examination every year can help determine whether the disease is progressing.
The AREDS researchers followed participants for an average of 6.3 years (with a maximum of eight years), so the effectiveness of the supplements beyond this time is unknown.
AREDS participants reported minor side effects from the treatments. About 7.5 percent of participants assigned to the zinc treatments - compared with five percent who did not have zinc in their assigned treatment - had urinary tract and prostate problems that required hospitalization. Participants in the two groups that took zinc also reported anemia at a slightly higher rate; however, testing of all patients for this disorder showed no difference among treatment groups. Yellowing of the skin, a well-known side effect of large doses of beta-carotene, was reported slightly more often by participants taking antioxidants.