Good nutrition is getting a close look by eye doctors, and with good reason. It may lead to better vision and it's something people can control.
Age-related macular degeneration is the most common cause of irreversible vision loss, and a number of risk factors are known to increase the risk, such as family history, smoking, high blood pressure and excessive exposure to bright sunlight. Some of those factors are outside your control, but many aren't.
Smoking triples the risk of developing macular degeneration. Even secondhand smoke doubles the risk. After 20 years of not smoking, however, the risks are the same as for nonsmokers, and even quitting later in life can reduce progression of ARMD and improve the potential success of treatment.
The most extensive study ever done regarding the effects of nutritional supplements on ARMD — The Age-Related Eye Disease Study — has shown that some supplements seem to help. Patients with at least intermediate ARMD decreased their risk of progression by 25 percent by supplementing with high-dose anti-oxidants and zinc.
The supplements used in the AREDS study were 500 milligrams of vitamin C, 400 international units (IU) of vitamin E, 25,000 IU of vitamin A (as 15 milligrams beta-carotene), 80 milligrams of zinc and 2 milligrams of copper. Smokers must avoid formulas with beta-carotene.
Good nutrition involves more than just taking supplements. Anti-oxidants are all around the grocery store. Think green, yellow and orange. Patients with diets high in spinach and collard greens are less likely to develop macular degeneration.
Two important macular pigments, lutein and zeaxanthin, are found in green leafy vegetables, including kale, mustard greens, turnip greens and Romaine lettuce, as well as in orange peppers, yellow corn, broccoli, avocados, oranges and egg yolks.
A deficiency in the mineral zinc has been found among some macular-degeneration patients. Zinc is found naturally in shellfish, fish, meat, oats, beans and peas.
Omega-3 fatty acids may help to decrease the likelihood of developing macular degeneration and serve to protect against ongoing retinal damage. Foods high in omega-3 include oily fish — salmon, sardines, tuna — walnuts and certain plant oils, including flaxseed and canola.
There is promising evidence that good nutrition can make a difference in retinal health, but so far the potential benefits on retinal diseases are more suggested than proven. However, the health of the retina is essential for vision, so limiting the damage and supporting health with sound nutrition would theoretically benefit a wide variety of retinal diseases.
Dr. Karyn Bourke is on staff at the Retina Care Center, 748 State St., Medford; 541-842-2020; www.retinacarecenter.org