Soy Does a Body Good

Eating soy-based foods is one of the simplest things you can do for your health. High in protein, low in fat, and packed with isoflavones, soy can lower cholesterol and protect against heart disease, and there may be a host of other benefits as well.

By PT Staff, published on March 1, 2001 - last reviewed on June 9, 2016

In recent years, psychologists and other health professionals have
made us realize that our health depends largely on our behavior. Eating
soy, it now appears, is one of the simplest things we can do to boost our

Once revered as a sacred crop in China, soybeans are one of the
richest plant sources of protein. In fact, the World Health Organization
considers it on par with meat and dairy proteins. But not only is this
low-fat dietary protein great news for vegetarians or dieters, a growing
body of research indicates that soy may help prevent many chronic
diseases. Many of its therapeutic benefits are believed to come from its
vast stores of isoflavones. These bioactive plant chemicals function like
weak estrogen -- a female hormone necessary for normal growth and
development -- by adjusting the hormone's effects when levels are too high
or low.

To get the most out of soy, health experts suggest eating whole
foods like tofu, soymilk and tempeh because they contain higher levels of
isoflavones than processed foods or supplements. Fortunately, there are
now a variety of soy and tofu products that are both convenient and
tasty. Soymilk can be found nationally in refrigerated sections of
supermarkets, and it easily replaces cow's milk for both drinking and

The biggest news is that soy lowers cholesterol and protects
against heart disease. An analysis of 38 studies published in the New
England Journal of Medicine found that eating soy lowers total levels of
cholesterol by 10% and LDL or "bad" cholesterol by 13%. In 1999, the FDA
gave soy the green light, stating definitively that eating 25 grams of
soy protein each day as part of a low-fat, low-cholesterol diet reduces
the risk of heart disease. Recently, the American Heart Association
revised its dietary guidelines to recommend soy as part of a
heart-healthy diet.

While research on other diseases isn't yet conclusive, scientists
believe that soy may also help with the following:

OSTEOPOROSIS: A 1998 study published in the American Journal of
Clinical Nutrition found that postmenopausal women who ate 40 grams of
soy protein a day significantly increased the bone density in their
spines. And a University of Iowa study found that women who consumed soy
with isoflavones maintained bone density, while those who didn't consume
isoflavones actually lost bone density. "The isoflavones in soy are
identical to a drug called Ipriflavone, a synthetic isoflavone used for
bone loss, so there's reason to think that isoflavones will do something
for bone health," says Mark Messina, Ph.D., an adjunct associate
professor of nutrition at Loma Linda University in California and former
program director for the National Cancer Institute (NCI). "In general, if
you substitute soy for animal protein, you'll lose less calcium from your
bones because animal protein causes calcium loss."

MENOPAUSE: Although some studies suggest that soy isoflavone pills
are no more effective than a placebo in fending off menopausal symptoms
like hot flashes and night sweats, several other studies suggest
otherwise. A 12-week-long Italian study found that postmenopausal women
taking soy containing 76 mg of isoflavones experienced a 45% reduction in
their symptoms, while those taking placebos reported only a 30%
reduction. And a study of 177 menopausal women presented at the Third
International Symposium on the Role of Soy in Preventing and Treating
Chronic Disease found that those who took 50 mg of soy isoflavones had
fewer and less severe hot flashes and night sweats than those who didn't
take isoflavones.

"Soy won't make hot flashes and night sweats go away, but it will
make them milder and slightly less frequent," says Gregory Burke, Ph.D.,
chairman of the Department of Public Health Sciences at Wake Forest
University School of Medicine in North Carolina. "And that may be enough
for many women."

CANCER: According to the NCI, soy is believed to coax cancerous
cells to revert to normal. It may also prevent tumors from obtaining
nutrients and block free radicals -- compounds that normally attack
bacteria and viruses -- from damaging healthy cells. "There are several
potent anti-cancer compounds in soy," says Clare Hasler, Ph.D., executive
director of the Functional Foods for Health program at the University of
Illinois. "I suspect that when the ongoing trials are completed, we'll
see that soy may protect against cancer." Because of its estrogenic
properties, soy appears most effective against hormone-related cancers
like prostate and colon. Another study presented at the same symposium on
soy found that soy reduced tumors by 40% to 60% in mice with prostate or
bladder cancer.

Epidemiological studies suggest that soy also protects against
breast cancer, and researchers often point to Japan and China where soy
consumption is high and breast cancer rates are low. Even so, scientists
recently discovered that, because consuming soy promotes breast cell
growth, doing so later in life may actually raise the risk of breast
cancer for postmenopausal women with a personal or family history of the
disease. To play it safe, consult your doctor if you're at risk for
breast cancer.

For those who want to stock up on soy, now's the time. April is
National Soy Foods Month, and supermarkets typically carry a wide variety
of soy foods like soy nuts, snack bars and instant shakes, all ready to
grab on the go. One easy -- and satisfying -- way to include 25 grams of soy
protein in your daily diet is to down a shake made with instant soy
protein powder. Other convenience foods like soy-based burgers, hot dogs,
deli meats and bacon have a taste and texture that's very similar to real
meats. So this April, think health and think soy.