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I am often asked about
the health benefits of soy. Are soy products, which have entered the
mainstream food supply, beneficial to most women? The answer is yes.
So why do we read that
soy isn’t healthful for all women? There has been widespread debate about
soy products and their effects on health, particularly breast health. The
results of studies have shown conflicting results, but continuing research
on the subject is helping to clarify some issues.
For example, there is a
body of research showing that soy is beneficial to your heart because it
lowers triglycerides and cholesterol, particularly LDL, or “bad”
cholesterol. There is also evidence that soy may support bone health by
inhibiting bone resorption, or calcium loss from your bones. In addition,
soy products have been shown to ease menopausal symptoms such as night
sweats and hot flashes.
The controversy about soy generally centers around breast health. Studies on
how soy affects a woman’s breast tissue have looked at the estrogen-like
effects of the soy-derived isoflavones genistein and daidzein. However,
these isoflavones have weak estrogenic properties compared with the estrogen
naturally produced by a woman’s own body.
A recent article in Advanced Practice in Acute Critical Care points
to some studies of women in Asia, in which Asian women who consumed a high
amount of soy in their diets had a lower risk of breast cancer than
Western women. Interestingly, these studies also found that when Asian women
move to the West and adopt the typical Western diet, their breast cancer
risks go up.
Epidemiological studies suggest that diets with high concentrations of soy
isoflavones are associates with a reduced risk for breast cancer.
Interestingly, other studies have associated lowered risk of adult breast
cancer with adolescent consumption of isoflavone-rich soy. In other words,
the age of exposure to isoflavones may be an important factor in reaping
their protective benefits. Still, animal and test-tube studies on soy
isoflavones have shown that they could increase the proliferation of breast
cancer cells.
A study published in the May 2005 journal Carcinogenesis offers still
another viewpoint. The authors suggest that a lot depends on how one ingests
soy. They found that when the isolated soy isoflavone genistein was
consumed, breast tumor growth was stimulated. This was not the case when
whole soy food products were ingested. Because soy products in Asian
countries are minimally processed, most women in Asia eat whole soy foods.
In the United States, however, many women frequently consume processed soy
products. These processed soy products contain large amounts of isoflavones
in the form of genistein capsules or powders. What’s missing? Processed soy
lacks any biologically active compounds found in whole soy foods.
Here’s the good news: products made with whole soy foods are widely
available. These include tofu, tempeh, soy flour, miso soup, soybeans (edamame),
soy protein powder, and soymilk. Soy products, preferably organic, should be
part of every woman’s plan for creating optimal health. Among the many
positive qualities, soy contains compounds that can block estrogen
receptors, inhibit enzymes that can induce cancer, and act as antioxidants.
Dr. Laurie Steelsmith (www.drlauriesteelsmith.com)
is a naturopathic physician and licensed acupuncturist with a private
practice in Honolulu, Hawaii. She is author of the critically acclaimed
book, Natural Choices for Women’s Health: How the Secrets of Natural
and Chinese Medicine Can Create a Lifetime of Wellness (Three
Rivers Press, 2005).
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