Imagine trying to read this alert with a large, dark circle obscuring the center of your computer screen. That's the dilemma for those who develop age-related macular degeneration (AMD), a retina disorder that begins at the center of the field of vision and gradually enlarges. AMD is the most common cause of blindness for those over the age of 55, and affects more than 15 million in the U.S. alone. But now scientists believe that many future cases of AMD may be prevented with the help of genetic research. In a study published just last month in Science Express, a team from Duke University and Vanderbilt University examined genetic data from nearly 500 AMD patients and more than 180 families with a history of AMD. The conclusion: a variant of a gene called complement factor H (CHF) may account for more than 40 percent of all cases of AMD. Researchers believe that further studies of this gene variant will give doctors an effective tool for predicting high-risk. In 2001, important research was reported from the Age-Related Eye Disease Study (AREDS); an ongoing clinical trial sponsored by the National Eye Institute, one of the federal government's National Institutes of Health. Over a period of eight and a half years, AREDS researchers recruited almost 3,600 study participants. On average, the subjects were tracked for 6.3 years, with vision exams every six months. All of the participants were between the ages of 55 and 80, and approximately equal numbers of women and men. Subjects were divided into categories depending on the state of their vision when recruited. For example: "Category 4" patients already had AMD at the beginning of the study, while "Category 2" patients showed only borderline AMD characteristics. Subjects in all categories were randomly assigned one of the following four regimens:
*Daily supplementation with antioxidants (500 mg vitamin C, 400 IUs of vitamin E, 15 mg beta carotene)
*Daily supplementation with zinc (80 mg of zinc oxide and 2 mg of cupric oxide)
*Daily supplementation with a combination of both antioxidants and zinc at the prescribed dosages
*Placebo After compiling the data, researchers found that when compared to the placebo group, subjects in the antioxidant group had a 17 percent lower rate of AMD, and subjects in the zinc group had an impressive 21 percent lower incidence of AMD. But those in the group that combined antioxidants and zinc cut their risk of AMD by a full 25 percent. A more recent round of research using AREDS data comes from a team at Johns Hopkins School of Medicine here in Baltimore. Applying the 2001 results to estimates of those in the U.S. who are at risk of AMD, the Hopkins researchers concluded that over the next 5 years, well over a million people will develop advanced AMD if they receive no preventive treatment. But if all 8 million at risk began to take supplements comparable to those in the AREDS study, more than 300,000 of them would prevent the onset of AMD and the vision loss associated with AMD. In what has to be considered a remarkable mainstream endorsement of the preventive effects of supplements, the authors of the study told Reuters news service that the intake of these vitamins and nutrients by people at risk of AMD should have "a major impact on them, as well as on the public health."
BUT WHO EXACTLY IS AT RISK OF AMD?
As the name of the disorder implies, age is the primary risk factor, with people over the age of 60 being in the greatest danger. Other risk factors include cigarette smoking and a history of immediate family members with AMD. In a previous alert I told you how the use of prescription blood pressure drugs called ACE inhibitors actually create a greater AMD risk than smoking does. Finally, women are also at somewhat more risk than men. All of the supplements used in the AREDS study are very safe at the dosage levels listed above. As always, you should talk to your doctor before starting any supplementation program, but for most people, the combination of antioxidants and zinc is an easy, relatively inexpensive way to fight off AMD and retain your sight.