So far, she has identified peptides
that lower blood pressure and cholesterol and others that may aid in
preventing cancer. She has even identified an "anti-obesity" peptide
that causes a feeling of fullness and slows the rate of stomach
emptying to impede weight gain.
Peptides can occur naturally in
soybeans, they can be a product of human digestion of soy, or they
can be obtained in the lab through enzymatic hydrolysis. "We expect
to identify at least 10 peptides that can be used to prevent or
manage heart disease and cancer," de Mejia said.
De Mejia believes that soy protein,
often overlooked in the fuss over soy isoflavones, is responsible
for many of soy's health benefits.
"We know that the peptide lunasin is
effective against skin cancer in mice, and we've also seen promising
results against prostate and breast cancer. Lunasin seems to inhibit
the malignant progress of these cells. And, although proteins are
not generally absorbed by the body, this peptide is absorbed in the
intestine, so the human body can use it," de Mejia said.
De Mejia's lab has analyzed 144 soybean
varieties for their lunasin levels, using the USDA Soybean Germplasm
Collection at the U of I. Her findings will be published soon in the
Journal of Agricultural and Food Chemistry.
This analysis will be useful in
developing lunasin-enriched cultivars and soy products, she said.
And the wide range of lunasin concentrations in soybean tells the
researcher that the peptide can probably be genetically manipulated,
making it a potential source of bioactive ingredients for functional
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De Mejia is analyzing commercially
available soy protein products -- including soy isolates,
concentrates and texturized soy protein -- for their lunasin content
and has found interestingly high levels. Dietary supplements that
are very high in isoflavones do not contain lunasin, she said.
She also wants to study fermented soy
products for the new peptides that may be found in them. "In the
United States, we're not used to fermented foods from soybeans,
although we do eat fermented foods from milk, such as yogurt.
Fermented foods are really better for you because the process
creates certain compounds, such as peptides, that have health
benefit," she said.
Soy is fermented in certain food
processing technologies, producing leftovers now used as animal
feed. "One of our projects is to try to recall lunasin from these
waste materials," she said.
"We know that soy products lower the
risk of developing age-related chronic diseases, such as cancer and
heart disease," de Mejia said. "But we're still trying to understand
what components in soy are responsible for its health benefits. This
research is exciting because we're learning that bioactive peptides
may be the reason soybeans are such a healthful food."
Other researchers involved in the study
were Miguel Vasconez, Ben O. de Lumen and Randall Nelson.
was funded by the Midwest Advanced Food Manufacturing Alliance,
FilGen Biosciences and the Research Board at the University of
[University of Illinois news release]