Soy May Be Protective, After All!

AnneW

Soy May Be Protective, After All!

AnneW

It's a never-ending discussion, it seems. Does soy help us or hurt us? This article seems to point toward benefits:

Soy compound linked to lower breast cancer risk

By Amy NortonFri Apr 11, 11:12 AM ET

Women with high blood levels of an estrogen-like compound found in soy seem to have a lower risk of developing breast cancer, a new study suggests.

Researchers found that among more than 24,000 middle-aged and older Japanese women, those with the highest levels of the compound, called genistein, were only one-third as likely as other women to develop breast cancer over 10 years.

Genistein is one of the major isoflavones, plant compounds found in soybeans, chick peas and other legumes that are structurally similar to the hormone estrogen, and are believed to bind to estrogen receptors on body cells.

While some studies have linked soy consumption with a lower risk of breast cancer, others have found no protective effect. Some animal research, in fact, has suggested that genistein might spur tumor development and growth. The new findings, reported in the Journal of Clinical Oncology, suggest that this is not the case in women, at least when genistein is consumed through food alone.

"This finding suggests a risk-reducing rather than a risk-enhancing effect of isoflavones on breast cancer, even at relatively high concentrations within the range achievable from dietary intake alone," write the researchers, led by Dr. Motoki Iwasaki of the National Cancer Center in Tokyo.

The study included 24,226 women ages 40 to 69 who gave blood samples and completed a dietary assessment, then were followed for an average of 10 years. During that time, 144 women were diagnosed with breast cancer.

When Iwasaki's team separated the women based on their blood levels of genistein at the study's start, they found that the one-quarter with highest levels were 65 percent less likely to develop breast cancer than the quarter of women with the lowest genistein levels.

There was no risk reduction seen among women with moderate levels of the isoflavone, however.

Most past studies on soy isoflavones and breast cancer have used dietary questionnaires, Iwasaki noted. "In contrast, our study used a direct measurement of plasma isoflavone levels, which provides not only an index of intake but also of the absorption and metabolism of isoflavone," the researcher told Reuters Health.

Together with past studies, Iwasaki said, the findings suggest that a high isoflavone intake from food may help lower breast cancer risk.

Whether the findings necessarily extend to women in Western countries is not clear, however. Japanese women, Iwasaki noted, typically consume soy isoflavones on a regular basis starting from a young age, which may influence the compounds' effects on breast cancer development.

SOURCE: Journal of Clinical Oncology, April 1, 2008.

Copyright © 2008 Reuters Limited. All rights reserved. Republication or redistribution of Reuters content is expressly prohibited without the prior written consent of Reuters. Reuters shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon.

Anne

Member_of_the_Club

When i asked the Johns Hopkins Ask-An Expert lady about soy she said within reason it wouldn't hurt and it might help. So many women here are avoiding soy but the advice I've gotten from all my oncs is that it is OK in moderation, so that is the advice I follow.



It makes sense to me that it might be protective because it isn't estrogen, it is a phytoestrogen, a plant estrogen. So, just as tamoxifen fools the er+ cancer cells into thinking they are getting their estrogen, thereby blocking the real estrogen, couldn't phytoestrogens serve the same function?

Rosemary44

They have said the benefit comes from early exposure to soy while a girl is in her adolescence.  I don't see anything in the story that says it would be beneficial for us who already had BC.  We're still on our own. 

AnnNYC

Well, at least it may not be harmful, which would allow many of us to continue eating foods we enjoy, and that are beneficial for other health reasons (i.e., eating a lot of "chickpeas and other legumes" because they're low-glycemic and their soluble fiber helps regulate blood sugar/insulin).