According to the Macular Degeneration Association, age-related macular degeneration—a disease of the retina that can lead to blindness—is the leading cause of blindness in Americans 65 and older. The Glaucoma Research Foundation states that glaucoma is the second leading cause of blindness in the world, with an estimated 2.2 million Americans affected.
Cataracts affect nearly 20.5 million Americans 40 and older, and by age 80, more than half of Americans have them. The Centers for Disease Control and Prevention (CDC) notes that over 5 million people have diabetic retinopathy.
We may not think much about our eyes, particularly if they’re working well. Research shows, however, that like the rest of the human body, the eyes are subject to not only age-related changes, but daily diet. According to a multidisciplinary roundtable of experts recently convened by the Ocular Nutrition Society (ONS), eye health is a significant, but under-appreciated public health issue. They stated that about 35 million Americans 40 and older have an eye disease, and that number is expected to grow to 50 million by 2020.
What’s missing, the group concluded, were key diet-derived nutrients that protect eye health. They noted that today’s American diet, full of processed foods, has robbed many Americans of the nutrients that are important to eye health.
Key Nutrients for Eye Health
Below are several of the nutrients the experts mentioned, and the doses found effective in studies.
- Zinc. A large study called the “Age-Related Eye Disease Study” found that people at high risk for advanced age-related macular degeneration (AMD) lowered their risk by about 25 percent when treated with a high-dose combination of vitamin C (500 mg), vitamin E (400 IU), beta carotene (50 mg), and zinc (80 mg). (Researchers added 2 mg of copper to prevent copper-deficiency anemia, which can happen in people who take high levels of zinc.) Zinc is naturally present in high concentrations in the retina, and also offers antioxidant protection. The American Optometric Association (AOA) also states that zinc plays a vital role in bringing vitamin A from the liver to the retina, and that impaired vision has been linked to zinc deficiency. They recommend zinc to individuals who are at a high risk for AMD. Food is the best source—try red meat, seafood, eggs, wheat germ, mixed nuts, black-eyed peas, tofu, and baked beans.
- Vitamin C. In addition to the aforementioned study, numerous other studies have found vitamin C to be critical to eye health. The AOA states that women using vitamin C for 10 years or more experienced a 64 percent reduction in the risk of developing cataracts. Other research showed that women taking a daily supplement of 364 mg experienced a 57 percent reduction in certain types of cataracts. Taken with other nutrients, vitamin C can also help prevent or slow the progression of AMD. Food sources include fruits and vegetables, particularly citrus fruits.
- Vitamin E. Vitamin E is thought to protect the cells of the eyes from damage with its powerful antioxidant properties. Unfortunately, a typical Western diet is low in this nutrient. Studies have indicated that the vitamin reduces the progression of AMD and cataract formation, particularly when combined with lutein and zeaxanthin. Food sources include nuts, salad and vegetable oils, peanut butter, fortified cereals and sweet potatoes.
- Beta-carotene. Beta-carotene is converted to vitamin A (retinol) in the body, and vitamin A is needed for good vision and eye health. A study published in 2010, however, we’re not getting enough. Experts from the University of Hohenheim noted that the current beta-carotene intakes from the diet do not fill the gap of low consumptions of dietary sources for pre-formed vitamin A in large populations of the U.S., Europe, and Asia. They recommended foods fortified with beta-carotene and dietary supplements. Current recommended intake: 2-4 mg per day. Researchers recommended that amount be increased to 7 mg per day. Though the mainstream coverage of research showing that high doses of beta-carotene are associated with an increased risk of lung cancer in high-risk groups of smokers may have scared some people off this supplement, these experts emphasized that for most populations, beta-carotene is an “indispensable safe source of vitamin A.”
- Lutein & zeaxanthin. These are also carotenoids, and the only ones found in the retina and lens of the eye. Epidemiological studies suggest that diets rich in these nutrients may help slow the development of AMD and cataracts. For example, in one study, those people eating a diet with the most lutein and zeaxanthin (as much as 5.8 mg per day) had a significantly lower risk for AMD than those who contained the least amount (as low as 1.2 mg per day). The Third National Health and Nutrition Examination Survey (NHANES III) showed that consuming 6 mg per day of the two combined was associated with reduced risk for developing AMD. The Nurses’ Health Study also found that consuming large amounts reduced (6 mg per day) reduced the need for cataract surgery. The average American consumes only 2 mg per day. Food sources include dark, green leafy vegetables, broccoli, orange peppers, corn, peas, and tangerines.
- Omega-3 fatty acids. A 2007 animal study found that omega-3 fatty acids protect against the development and the progression of retinopathy. The researchers used EPA and DHA derived from fish. The AOA notes that DHA is found in the highest concentration in the retina, and that studies in pre-term and full-term infants suggested that omega-3s may be essential for optimal visual development. Typical daily intake in the U.S. is estimated at 1.6 grams per day, which yields 0.1 to 0.2 grams per day of EPA and DHA. This is well below the American Heart Association recommended level of 0.5 to 1.0 grams per day of EPA and DHA. The FDA has stated that consuming up to 3 grams per day of DHA and EPA is generally considered as safe. Food sources include sardines, salmon, flaxseeds, and walnuts.
- Vitamin D. According to a recent animal study, supplements of vitamin D3 may boost visual function. It was also associated with a reduction in the accumulation of amyloid beta, said to be a risk factor for AMD. An earlier study found that women who consume high levels of vitamin D through certain fish, dairy and eggs (15.1 mcg daily) could lower their risk of AMD by 59 percent. And another animal study early in 2012 indicated that vitamin D3 reduced the effects of ageing in the eyes, helping function and vision. In addition to sunlight, cod liver oil, salmon, mackerel, tuna, sardines, and milk are good sources of vitamin D.
Do you take supplements for eye health?
“Experts Declare Need for Eye Health Education,” Reuters, April 16, 2012, http://www.redorbit.com/news/health/1112514395/experts_declare_need_for_eye_health_education/.
Lara Salahi, “Truth Squad: Supplements for Eye Health,” ABC News, October 21, 2009, http://abcnews.go.com/Health/EyeHealth/supplements-eye-health-work/story?id=8871245#.UJ2BiHbCMYY.
Nathan Gray, “Expert panel highlights need for beta-carotene fortification,” Nutraingredients.com, November 12, 2012, http://www.nutraingredients-usa.com/Research/Expert-panel-highlights-need-for-beta-carotene-fortification.
National Eye Institute, “Omega-3 Fatty Acids Protect Eyes Against Retinopathy, Study Finds,” National Institutes of Health, June 24, 2007, http://www.nei.nih.gov/news/pressreleases/062407.asp.
Stephen Daniells, “Vitamin D shows eye health benefits: Study,” Nutraingredients-usa.com, August 29, 2012, http://www.nutraingredients-usa.com/Research/Vitamin-D-shows-eye-health-benefits-Study.
Courtney Hutchison, “Vitamin D Protects Against Age-Related Vision Loss,” ABC News, http://abcnews.go.com/Health/EyeHealth/vitamin-protects-age-related-vision-loss-women/story?id=13348461#.UJ2hGXbCMYY.
Nathan Gray, “Vitamin D may help functioning of ageing in eyes: Study,” Nutraingredients.com, January 18, 2012, http://www.nutraingredients.com/Research/Vitamin-D-may-help-functioning-of-ageing-in-eyes-Study.