While eggs are well known to be an excellent source of
proteins, lipids, vitamins and minerals, researchers recently discovered
they also contain antioxidant properties, which helps in the prevention
of cardiovascular disease and cancer.
Jianping Wu and fellow researchers examined egg yolks produced by
hens fed typical diets of either primarily wheat or corn. They found the
yolks contained two amino acids, tryptophan and tyrosine, which have
high antioxidant properties.
After analyzing the properties, the researchers determined that two
egg yolks in their raw state have almost twice as many antioxidant
properties as an apple and about the same as half a serving (25 grams)
of cranberries.
However, when the eggs were fried or boiled, antioxidant properties
were reduced by about half, and a little more than half if the eggs were
cooked in a microwave.
“It’s a big reduction but it still leaves eggs equal to apples in their antioxidant value,” said Wu.
The discovery of these two amino acids, while important, may only
signify the beginning of finding antioxidant properties in egg yolks,
said Wu.
“Ultimately, we’re trying to map antioxidants in egg yolks so we have
to look at all of the properties in the yolks that could contain
antioxidants, as well as how the eggs are ingested,” said Wu, adding
that he and his team will examine the other type of antioxidant already
known to be in eggs, carotenoids, the yellow pigment in egg yolk, as
well as peptides.
In previous research, Wu found that egg proteins were converted by
enzymes in the stomach and small intestines and produced peptides that
act the same way as ACE inhibitors, prescriptions drugs that are used to
lower high blood pressure.
That finding defied common wisdom and contradicted the public
perception that eggs increased high blood pressure because of their high
cholesterol content. Additional research by Wu suggests the peptides
can be formulated to help prevent and treat hypertension.
Wu is convinced the peptides also have some antioxidant properties,
which leads him to suggest that when he completes the next step in his
research, the result will likely be that eggs have more antioxidant
properties than we currently know.
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