Posted on: 16.05.2021 Posted by: Drlark Comments: 0

June 10, 2004


Breast Health

Making Sense of the Soy Controversy

Back in 2000, the New York Times ran an

article by two researchers from the Food and Drug Administration

(FDA) who claimed that soy isoflavones may work to “speed up”

the proliferation of cancer cells that are dependent upon estrogen

for their growth. This article, paired with a few studies that found

that estrogen-like isoflavones found in soy stimulated potentially

cancerous cell growth in premenopausal women, sent many women into

a panic.

I firmly believe that the panic has very little basis. I don’t find

these studies to be very convincing, especially when compared to

the breadth and depth of studies I’ve read touting the cancer-shielding

attributes of soy. Specifically, a multitude of studies have shown

that soy may actually help to combat breast cancer in a number of

different ways, including:

1. Blocking estrogen receptor sites. Soy isoflavones are

similar to your body’s own natural estrogens, only much weaker and

less potent. Like estrogen, they can bind to estrogen receptor sites

within the breast without exerting a dangerous estrogen-like influence.

As a result, they compete with and block your own estrogen, thereby

jamming these receptor sites and reducing the potential for your

estrogen to stimulate the growth of cancer.

2. Inhibiting tumor-induced angiogenesis (growth of new blood

vessels). One study done in 1993 found that the soy isoflavone

genistein actually blocked the ability of the tumor to grow new

blood vessels. These vessels supply the large amounts of oxygen,

energy, and nutrients required for unrestrained tumor growth, and

remove the large amounts of waste material created. Because tumors

can’t grow large enough to be clinically significant if angiogenesis

is blocked, this finding is very encouraging.

3. Preventing cellular damage that can trigger conversion of

normal cells to cancerous ones. Research from the July 2002

issue of Cancer Epidemiology, Biomarkers and Prevention,

found that women who ate a diet rich in soy products were 55 percent

less likely to have abnormal breast tissue growth than women who

consumed the least amount of soy. Researchers concluded that these

findings may have significant implications in breast cancer prevention.

Most telling to me are the long-term observances of real women in

the real world and their experiences with soy. In my own practice,

I have counseled women who had breast cancer and were also consuming

soy foods. Not only did they thrive on this diet, but they also

remained cancer-free. Additionally, in countries such as Japan or

China, where soy is a dietary staple, women are four to six times

less likely than their American counterparts to suffer from breast

cancer. And, researchers found that when Japanese women adopt a

more Western, lower-soy diet, their breast cancer rate increases.

However, based on a study from the May 2002 issue of Cancer Research,

I suggest that you err on the side of caution and avoid using pure

soy isoflavones if you have breast cancer and are taking tamoxifen.

Researchers investigated the interactions between dietary genistein

and tamoxifen (an estrogen antagonist used in the treatment of estrogen-dependent

breast cancer) by implanting estrogen-dependent breast cancer cells

in mice who had had their ovaries and thymus removed. They found

that genistein negated or overwhelmed the inhibitory effect of tamoxifen.

Based on these findings, they urged postmenopausal women to exercise

caution when consuming dietary genistein while taking tamoxifen.

Read More on Breast Health:

Getting Started

Breast Cancer

Risk Factors for Breast Cancer

Fibrocystic Disease

Keep it SIMPLE tip — Exercise Lowers Breast Cancer


Nutritional Therapies

Change your Lifestyle

Caffeine: Friend or Foe

Soy Controversy

Complementary Therapies

Primavera Recipe

Oxygen Therapy and Oxidants



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