Soy Soothes the Circuits in Body
By Judy McBride
February 14, 2000
Human body cells are constantly
barraged with chemical signals that pester them to respond. Miraculously, they
do a pretty good job of filtering out the noise and staying focused
on their purpose. But some cells lose the ability to regulate these signals,
and they react before they should. Researchers now believe this loss
contributes to chronic diseases, such as cancer and heart disease.
Foods play an important role in filtering out this chemical noise. Test tube
studies more than a decade ago show that a phytonutrient in soy
foods--genistein--dampens communication from the cells surface to its
interior. Now, an Agricultural Research
Service study gives the first evidence of this dampening effect in an
For four weeks, chemist Norberta Schoene, based at the ARS
Nutrient Requirements and
Functions Laboratory in Beltsville, Md., fed young rats diets containing
soy protein with high or low levels of genistein. Then she measured how the
animals blood platelets responded. Platelets are quite sensitive to
outside signals and so are a good model for studying cell signaling. In three
different tests, the platelets from the animals receiving the high-genistein
diet showed less response to such signals.
Schoenes hypothesis: Isoflavones may reduce over-responsive signaling
that produces chronic disease. For example, if an order to divide gets
heard by too many cells, it could lead to unrestrained growth as in
cancer or an overactive immune system.
Japanese diets on average contain about 10 times more soy than North
American diets, and the Japanese have a lower incidence of cancer and heart
disease. The genistein-rich diets in this study had the equivalent of twice the
average Japanese genistein intake. The genistein-poor diet contained the
equivalent of the U.S. intake of soy. Tofu, tempeh and miso are some soy foods
rich in genistein and other isoflavones.
An article about this research is in the February issue of Agricultural Research magazine.
Scientific contact: Norberta W. Schoene, ARS Nutrient Requirements
and Functions Laboratory, Beltsville, Md., phone (301) 504-8388, fax (301)