biochemist Elizabeth Johnson extracts lipids from blood plasma to test for
carotenoids. Click the image for more information about it.
Absorbing News About Eggs and
Lutein By Rosalie Marion Bliss
August 18, 2004
The human body is better able to absorb eye-healthy lutein from
eggs than from other dietary sources of the carotenoid, according to a study
funded by the Agricultural Research
Service and the Egg Nutrition
Center in Washington, D.C.
Lead nutritional biochemist Elizabeth J. Johnson and colleagues
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.
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 older Americans.
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.
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
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.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.