soy estrogens and breast cancer
Published by Bronwyn Schweigerdt on June 8, 2009 at 3:41 PMLadies, if you haven't been convinced that soy and phytoestrogens from soy products are beneficial yet, here's more news: the estrogens found in soy and soy protein prevent breast cancer.
A major study published in June's edition of the American Journal of Clinical Nutrition (Am J Clin Nutr 89: 1920-1926, 2009) studied the diets of 73,223 Chinese women over a period of 7.4 years. They found that women who consumed the most soy estrogens, or isoflavones, from food were 59% less likely to develop breast cancer than women who consumed the least. Also, adolescent girls who consumed the most isoflavones from soy foods were 43% less likely to develop premenopausal breast cancer than girls who consumed fewer soy protein.
In the words of the study authors, "This large, population-based, prospective cohort study provides strong evidence of a protective effect of soy food intake against premenopausal breast cancer."
The reason soy estrogens work to prevent breast cancer is because isoflavones have anti-estrogenic - as well as anticarcinogenic - properties. Soy estrogens don't mimic estrogen in the body as many people think they do (unless estrogen levels are dangerously low), but actually lower estrogen levels by keeping estrogen from entering the cells. By blocking cell receptors, soy estrogens keep estrogen levels from climbing high enough to encourage the growth of cancer cells. Also, isoflavones have cancer-fighting properties to boot.
Soy is a huge area of confusion in popular culture (in the U.S.) but not in scientific circles - now you can see why. If you need more encouragement, see past posts citing studies on soy and reproductive cancer. There are tons!
So whether it's tempeh, tofu, soy milk, or edamame - enjoy worry free.
Labels: soy estrogens
7 comments:
Again, good to now! Thanks for posting- I'm glad I eat a lot of soy.
What about soy and fertility? As someone who is hoping to conceive soon (and who eats a lot of soy), I've been doing a lot of reading- and everything I have read says that lots of soy is not good when you're trying to conceive. Is this old science, or a different ballgame (from breast cancer)?
Good question Mara! I will make that the subject of my next post.
Do you think only studying Chinese women may lead to faulty results? Is it possible they are just less prone to cancer as a race? Like how African-Americans are most susceptible to sickle cell anemia?
I'm curious to see a more diverse study.
Thanks for the post, though. I struggle to find credible studies on the internet. :)
Tracy, unfortunately, Chinese women in the U.S. are just as likely to develop breast cancer as Caucasian women, so I don't think this study is biased in that way.
It does seem most studies on soy are done on Asian women however, which is likely due to the fact that they consume much more soy than western women. I agree, it'd be nice to see this study on another population or two.
Currently Americans who consume soy are probably eating a lot MORE soy than Asians. Asians do not for example use soy to replace meat. They don't drink soy milk every day or consume protein shakes with soy protein isolates. They mainly use fermented soy such as miso and soy sauce. Also to compare Asian women who have lower breast cancer rates should also consider that this might have nothing to do with soy and might be from other factors like lower BMI, amount of exercise, having lower levels of hormones in farm animals etc.
Currently there is much said on the fact that soy protein isolate is processed with high amounts of aluminum and other chemicals. What about that?
There is so much confusing info on soy lately. Another study I read about soy states that children consuming soy as infants were developing puberty at an early age such as 8 years old.
We already get estrogens from many unknown sources such as plastics, dairy products and some meats. Why add even more to the diet?