February is Age-Related Macular Degeneration (AMD) Awareness Month. AMD is the leading cause of severe, irreversible vision loss in people over age 50. The National Eye Institute, a division of the National Institute of Health, estimates that the number of people with AMD is expected to more than double from 2.07 million to 5.44 million by the year 2050.
What is AMD?
Age-Related Macular Degeneration (AMD) occurs when there are changes to the macula -- a small portion of the retina that is located on the inside, back layer of the eye that is responsible for central vision. There is a loss of central vision that can occur in two forms: "dry" (atrophic) and "wet" (exudative).
How is AMD Treated?
Most people with AMD have the "dry" form, for which there is no known cure. The less common "wet" form may respond to laser procedures and medication injections, if diagnosed and treated early.
People at high risk for developing advanced AMD should consider taking the antioxidant-zinc combinations studied in the AREDS and AREDS2 clinical trials. Those who are considered to be "high risk" individuals are defined as having either:
Intermediate AMD in one or both eyes. Usually involves little or no vision loss.
Advanced AMD in one eye, but not the other eye. Involves either a breakdown of cells in the retina (called geographic atrophy or dry AMD), or the growth of abnormal blood vessels under the retina (called neovascular or wet AMD). Either of these forms of advanced AMD can cause vision loss.
What are the AREDS and AREDS2 Trials?
In 1992, researchers at the National Eye Institute began to study whether daily intake of certain vitamins and minerals could reduce the risk of advanced age-related macular degeneration (AMD). In 2001, the results of the Age-Related Eye Disease Study (AREDS) were reported: a nutritional supplement (referred to as the AREDS formulation) can reduce the risk of developing advanced AMD by about 25 percent over a five-year period. The original AREDS formulation contained vitamin C, vitamin E, beta-carotene, zinc, and copper.
In 2006, the same research group began a second study called Age-Related Eye Disease Study 2 (AREDS2) to determine if they could improve the AREDS formulation. AREDS 2 was a multi-center, randomized trial designed to assess the effects of oral supplementation of macular xanthophylls (lutein and zeaxanthin) and/or long-chain omega-3 fatty acids (docosahexaenoic acid) [DHA] and eicosapentaenoic acid [EPA]) on the progression to advanced age-related macular degeneration (AMD). An additional goal of the study was to assess whether forms of the AREDS nutritional supplement with reduced zinc and/or no beta-carotene works as well as the original supplement in reducing the risk of progression to advanced AMD.
Here’s a recap of the changes in the AREDS2 trial compared to the original AREDS trial:
- Substituted carotenoids: Replaced all 15 mg of beta-carotene with macular xanthophylls (10 mg lutein and 2 mg zeaxanthin)
- Added 1000 mg of omega-3 fatty acids (350 mg DHA and 650 mg EPA)
- Lowered the dose of zinc from 80 mg to 25 mg
The AREDS2 Formulation
Based on the results of the AREDS and AREDS2 clinical trials, the recommended combination of nutrients (known as the AREDS2 formula) is as follows:
+ 500 milligrams (mg) of vitamin C
+ 400 international units of vitamin E
+ 10 mg of lutein
+ 2 mg of zeaxanthin
+ 80 mg of zinc (as zinc oxide)
+ 2 mg of copper (as cupric oxide)
This formulation can be found in over-the-counter products. When you are choosing an AREDS2 supplement, check the ingredients list to see if it has everything you need. Some types of supplements have different ingredients than what’s recommended for AMD.
Disclaimer: High-dose supplemental nutrients, as found in the AREDS2 formula, can sometimes interfere with medications and compete with other vital nutrients for absorption in the body. Individuals who are considering taking an AREDS2 supplement should discuss this with their primary care physician and/or optometrist to determine which formulation, if any, is right for you.
Supplementation, Not Substitution
The AREDS2 formulation is not a substitute for a multivitamin, nor is a multivitamin a substitute for the AREDS2 formulation. A healthy diet, rich in a variety of colorful fruits and vegetables is preferred over supplementation; however, in the case of the AREDS2 formula, the high levels of vitamins and minerals are difficult to achieve from diet alone. Keep in mind that previous studies have suggested that people who have diets rich in green, leafy vegetables—excellent sources of the carotenoids lutein + zeaxanthin—have a lower risk of developing AMD. In the AREDS2 trial, the people who seemed to benefit the most from taking macular xanthophylls (lutein + zeaxanthin) were those who were lacking these nutrients in their diet. Within this group, those who received lutein + zeaxanthin supplements had a 26 percent reduced risk of developing advanced AMD compared with those who did not receive the supplements.
While the AREDS2 formula is better than doing nothing, it is not the final solution to help prevent, reverse, or slow the development of early AMD. The study was designed to slow progression of moderate to severe, advanced AMD. There are many more nutrients that can affect macular function, which I will cover in another blog post.
Chew et al. “Long-Term Effects of Vitamins C, E, Beta-Carotene and Zinc on Age-Related Macular Degeneration.” Ophthalmology, published online April 11, 2013.
AREDS2 Research Group. “Lutein/Zeaxanthin and Omega-3 Fatty Acids for Age-Related Macular Degeneration. The Age-Related Eye Disease Study 2 (AREDS2) Controlled Randomized Clinical Trial.” JAMA, published online May 5, 2013.
AREDS2 Research Group. “Lutein/Zeaxanthin for the Treatment of Age-Related Cataract.” JAMA Ophthalmology, published online May 5, 2013.