Proper supplement use advised for people with age-related macular degeneration

November 1, 2009

When patients visit Greg E. Evans, OD, at his practice near Palm Springs, CA, a routine part of the exam includes a thorough assessment of their macular health.

Age-related macular degeneration (AMD) is the leading cause of blindness in adult Americans. At greatest risk are patients aged ≥ 66 years, those who smoke, those with a family history of macular degeneration, and possibly those with hypertension, high cholesterol, and obesity, according to The Eye Digest, an online publication of the University of Illinois Eye & Ear Infirmary.

Vitamins get increased recognition

The use of vitamins to boost ocular health and potentially slow the progression of AMD has changed over the past 8 years, after results of the landmark Age-Related Eye Disease Study (AREDS) were released in 2001. This major clinical study, sponsored by the National Eye Institute (NEI), found that people who are at high risk for developing advanced AMD should consider taking the combination of nutrients used in the study-vitamin C, vitamin E, beta-carotene, zinc, and copper. According to data from AREDS, this formulation reduced the rate of progression in people at high risk by about 25%.

Once relegated to "alternative therapy" status, vitamins are now gaining stature among mainstream medical professionals, said Michael A. Samuel, MD, a retina specialist in Los Angeles, and author of Macular Degeneration: A Complete Guide for Patients and their Families.

"The original AREDS study was the first time Western and Eastern medicine met, where vitamins were shown to be effective for a disease we had no treatment for," Dr. Samuel said. "We, as a specialty, were shocked when the results came out. I don't think anyone thought vitamins would have such an effect on this devastating disease."

Further study, however, questioned the results, so a second study-AREDS2-was launched. Enrollment concluded in June 2008; participants will be followed for 5 to 6 years. Preliminary findings have shown some improvement over the original formula, Dr. Samuel said.

Zinc, for example, showed a clear benefit in the original AREDS trial, but the original formula included 80 mg, a dose now considered too high because it has been linked with the formation of beta-amyloid plaques, which are associated with the onset of Alzheimer's disease. "You have a population suspected to be at risk for Alzheimer's because of their age, and now we're adding to that risk," Dr. Samuel said.

Also in question is whether our bodies are capable of absorbing so much zinc at one time, he added.