Zeaxanthin May Decrease Your Risk
of Macular Degeneration
by George Torrey, Ph.D.
Zeaxanthin is the dominant component within the central macula.
The macular pigment is highly organized within the retina of the human eye. Studies show that the retina contains two carotenoids, lutein and zeaxanthin, with the greatest concentration at the center. Within the central macula, zeaxanthin is the dominant component, up to 75% of the total, whereas in the peripheral retina, lutein predominates, usually being 67% or greater. Typical carotenoid concentrations within other human tissues are much lower. Data show that the macular pigment increases through dietary supplements. Evidence points to a correlation between macular pigment density and a reduction in the risk for age-related macular degeneration (AMD) (1).
AMD, the leading cause of blindness in people over age 55 in Western industrialized nations, occurs when the macula, about the size of a pencil eraser, is destroyed by the aging process. In a study by The Schepens Eye Institute, an affiliate of Harvard Medical School, subjects over age 60 with high macular pigment density had the same visual sensitivity as the younger subjects. Older subjects with low macular pigment density had lower visual sensitivity than the younger subjects (2).
Fruits and vegetables are the most important dietary source of carotenoids. To date, there is no comprehensive information on the separate content of lutein and zeaxanthin in fruits and vegetables. Most analytical systems measure lutein and zeaxanthin together. However, the AMDF has chosen data, illustrated in the following graph, which measure zeaxanthin specifically.
The USDA-NCC Carotenoid Database was created through a collaborative effort between the USDA and the Nutrition Coordinating Center (NCC) at the University of Minnesota. The AMDF has calculated the amount of zeaxanthin per serving based on the amount of zeaxanthin per 100 grams as provided by the USDA-NCC database. The USDA-NCC database also calculated 457 micrograms of zeaxanthin in 100 grams of enriched yellow cornmeal, 173 micrograms of zeaxanthin in 100 grams of cooked kale and 267 micrograms of zeaxanthin in 100 grams of cooked turnip greens. The British Journal of Ophthalmology (3) reports the highest mole percentage (% of total) of zeaxanthin can be found in orange peppers, at 37% mole weight and egg yolk at 35% mole weight.
We believe this limited information available today can nevertheless serve as a guide for our readers to increase the quantity of zeaxanthin in their diet. There is no known optimal amount of zeaxanthin at this time. However, research indicates the nutrients in these foods may increase the concentration of macular pigment, thus building more healthy eyes. D. Max Snodderly, Ph.D., head of the laboratory at The Schepens Eye Research Institute, states, “It appears that people lose visual sensitivity before the worst stages of disease. But with the right nutritional program, you might prevent the low macular pigment group from getting worse, and in the best cases even recover some of the lost function.” Dr. Snodderly, with co-authors Billy Hammond and Billy R. Wooten, reported their findings in Investigative Ophthalmology & Visual Science.
Since no daily recommended allowance of zeaxanthin currently exists, JoAnn Prophet, a registered dietitian with the American Institute for Cancer Research in Washington, D.C., advises people to follow the usual dietary recommendations. These recommendations suggest eating at least five servings of a variety of fruits and vegetables daily and to add extra grains and beans to daily meals. This should enable people to reap the benefits of the hundreds, perhaps thousands, of phytochemicals that can help prevent disease and promote good general health.
Phytochemicals are naturally occurring compounds found in plants – fruits, vegetables and grains. Experts think that phytochemicals may play a major role in slowing the aging process.
Phytochemicals were discovered only within the last ten years, and researchers are still trying to assemble the needed data on their potential. Ms. Prophet advises that information on the 500 newly-discovered phytochemicals currently being examined by scientists will probably surface in news reports on a regular basis as individual fruits and vegetables are associated with specific phytochemicals (4).
George Torrey, Ph.D., a graduate of Brown (‘61), Harvard (‘62) and the Univ. of Connecticut (‘68), writes for the AMDF Newsletter and the AMDF Web site. Both his parents suffered from macular degeneration.
1. “Analysis of Zeaxanthin Distribution within Individual Human Retinas” by John T. Landrum, Richard A. Bone, Linda L. Moore, and Christina M. Gomez, Methods In Enzymology (1999, 299: 457-467).
2. Investigative Ophthalmology & Visual Science (Feb. 1998, Vol. 39, No. 2).
3. The British Journal of Ophthalmology (Aug. 1998, 82: 907-910)
4. “The promise of phytochemicals” by JoAnn Prophet, R.D., MSNBC.com on June 26, 2000.