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An Egg a Day May Keep Macular Degeneration Away
Aug. 18, 2004 An egg a day may help keep
age-related macular degeneration away, according to a new study that
says people are better able to absorb eye-healthy lutein from eggs than
any other dietary source.
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What is Macular
Degeneration
By Mayo
Clinic staff
Age-related macular degeneration is a
chronic eye disease that occurs when tissue in the macula, the
part of your retina that's responsible for central vision,
deteriorates. The retina is the layer of tissue on the inside
back wall of your eyeball. Degeneration of the macula results in
blurred central vision or a blind spot in the center of your
visual field.
The first sign of macular
degeneration may be a need for more light when you do close-up
work. Fine newsprint may become harder to read and street signs
more difficult to recognize. Eventually you may notice that when
you're looking at an object, what should be a smooth, straight
line appears distorted or crooked. Gray or blank spots may mask
the center of your visual field. The condition may progress
rapidly, leading to severe vision loss in one or both eyes.
Macular degeneration affects your
central vision, but not your peripheral vision; thus it doesn't
cause total blindness.
Read more
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The researchers suspect that lutein from eggs is
more readily absorbed into the bloodstream than lutein from other
sources because of components in the egg's yolk, such as lecithin.
Low lutein intake is implicated as a risk factor in
age-related macular degeneration, the leading cause of vision loss among
senior citizens. In the eye, the macula is in the retina, directly
behind the pupil, and is responsible for central vision. Lutein and a
related dietary carotenoid, zeaxanthin, accumulate within the macula and
imbue a yellow pigment that helps protect the eye.
The new findings suggest eggs are an inexpensive
source of highly bioavailable lutein, though more than one egg per day
would provide higher-than-recommended amounts of dietary cholesterol.
Lead nutritional biochemist Elizabeth J. Johnson
and colleagues with the
Carotenoids and Health Laboratory
at the Jean Mayer USDA
Human Nutrition Research Center on
Aging at Tufts University in Boston, Mass., conducted the
study. The findings are reported in the August issue of the
Journal of Nutrition.
Ten volunteers, during four separate test phases,
consumed either cooked spinach, eggs or one of two types of lutein
supplements. Each source provided 6 milligrams (mg) of lutein per daily
dose. Johnson measured lutein concentrations in the volunteers' blood
serum before and after each test phase. When each volunteer ate eggs as
the source of lutein, their lutein blood serum levels were about three
times greater than after consuming the same dose of lutein from the
other sources.
Federal surveys report the average American
consumes only about two mg of lutein daily, but a salad of one egg and
one cup of spinach would easily double that by providing the equivalent
of about four milligrams of lutein.
The study was funded by the
Agricultural Research Service
and the
Egg Nutrition Center in
Washington, D.C. ARS is the
U.S. Department of Agriculture's
chief scientific research agency. |
