By Maureen Williams, ND
Healthnotes Newswire (November 16, 2006)—Eating eggs might help protect the eyes from a common age-related disease—without raising cholesterol levels.
Age-related macular degeneration is a progressive eye condition that can lead to blindness. As the macula (a part of the retina) is damaged, vision becomes blurry and dark patches can appear at the center of the visual field.
A number of studies have found that specific antioxidants including vitamin C, vitamin E, beta-carotene, zinc, and selenium can protect against macular degeneration. Lutein and zeaxanthin, carotenoids found in spinach, kale, collards, and some other fruits and vegetables, are strong antioxidants that accumulate in the macula. Some studies have found that they can protect against oxidative damage and degeneration in the eyes, and even reverse it.
Egg yolks are known for being rich in fat and cholesterol, but many important nutrients are also concentrated into egg yolks, including minerals, B vitamins, and antioxidants. Antioxidant carotenoids such as lutein and zeaxanthin contain pigments that give egg yolks their yellow color.
In a new study, published in the Journal of Nutrition, 33 people age 60 or older were divided into two groups. During the first five weeks, one group ate one egg per day while the other group ate no eggs; both groups stopped eating eggs for a period of time and then the groups were reversed for another five weeks.
In the egg-eating groups, blood levels of lutein and zeaxanthin rose 26% in the first phase of the study and 38% in the second phase. Neither group experienced any significant change in their cholesterol levels.
The commercial eggs used in this study provided an average of 143 mcg of lutein and zeaxanthin. Previous studies which have found that supplementing with lutein prevents macular degeneration have used 6 to 10 mg per day—42 to 70 times the amount supplied by eggs in this study. However, studies have shown that the lutein in eggs is better absorbed than the lutein in green vegetables, or even in lutein supplements.
Most commercial eggs come from chickens that are fed processed grains all year, but there is good reason to believe that eggs from chickens that eat fresh greens could have higher concentrations of the pigments that protect the eyes. “When the chickens are in their winter yard eating mostly grains the yolks of their eggs become a paler yellow,” said Phil Rice, a systems researcher and educator who also maintains a flock of 75 organic laying hens in Vermont. “In the summer, though, when the chickens are in the pasture eating clover and grasses, the yolks become nearly orange. They love the fresh vegetation, and they—and their eggs—are healthier for it.”
One regular egg per day, despite having relatively little lutein and zeaxanthin, was enough to raise these antioxidant levels in seniors without raising their cholesterol levels. This finding suggests that eggs—and possibly eggs from chickens that eat grass and other fresh vegetation in particular—could be a part of a healthy diet for older people trying to prevent macular degeneration.
(J Nutr 2006;136:2519–24)
Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, VT, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.
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