Soy & Breast Cancer

Soy & Breast Cancer
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Should women with estrogen-receptor positive breast cancer avoid soy foods?

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What about soy foods like tofu? Harmful? Harmless? Or helpful? Well, researchers took Chinese dwarf hamsters—can you imagine hurting a hamster? Well, they were fed the human equivalent of 300 cups of soy milk every day, and didn’t do so well.

But what does the human data show? From just the last couple months: eating soy can cut our diabetes risk in half, can help us double our weight loss, for those on a diet, and drop our bad cholesterol 14%. Even just adding soy milk to our diet can have a measurably powerful effect on reducing cardiovascular risk.

Let’s bump it up a notch: not just soy, but soy for women with active estrogen receptor-positive breast cancer. The phytoestrogens—the plant estrogens in soy—protect one’s breast tissue from the more powerful ovarian estrogens. And so, in terms of preventing breast cancer, the only question has been: does soy cut our risk by 30%, or cut our risk by 50%?

But what if you already have breast cancer that reacts to estrogen? Do we want to be consuming any kind of estrogenic-type compounds? This used to be one of the most controversial questions in the field of nutrition, until now.

Soy intake and breast cancer survival on Long Island. What do you think? Harmful? Harmless? Or helpful?

Well, researchers calculated all-cause mortality for those women diagnosed with breast cancer eating soy, or not eating soy. And those eating soy cut their risk of dying by 50%! So not only does soy prevent breast cancer, but women with breast cancer eating soy live longer.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Dianne Moore.

Please consider volunteering to help out on the site.

What about soy foods like tofu? Harmful? Harmless? Or helpful? Well, researchers took Chinese dwarf hamsters—can you imagine hurting a hamster? Well, they were fed the human equivalent of 300 cups of soy milk every day, and didn’t do so well.

But what does the human data show? From just the last couple months: eating soy can cut our diabetes risk in half, can help us double our weight loss, for those on a diet, and drop our bad cholesterol 14%. Even just adding soy milk to our diet can have a measurably powerful effect on reducing cardiovascular risk.

Let’s bump it up a notch: not just soy, but soy for women with active estrogen receptor-positive breast cancer. The phytoestrogens—the plant estrogens in soy—protect one’s breast tissue from the more powerful ovarian estrogens. And so, in terms of preventing breast cancer, the only question has been: does soy cut our risk by 30%, or cut our risk by 50%?

But what if you already have breast cancer that reacts to estrogen? Do we want to be consuming any kind of estrogenic-type compounds? This used to be one of the most controversial questions in the field of nutrition, until now.

Soy intake and breast cancer survival on Long Island. What do you think? Harmful? Harmless? Or helpful?

Well, researchers calculated all-cause mortality for those women diagnosed with breast cancer eating soy, or not eating soy. And those eating soy cut their risk of dying by 50%! So not only does soy prevent breast cancer, but women with breast cancer eating soy live longer.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Dianne Moore.

Please consider volunteering to help out on the site.

Doctor's Note

More on soy’s role in preventing breast cancer:

BRCA Breast Cancer Genes and Soy
Breast Cancer Survival and Soy
GMO Soy and Breast Cancer

And check out my video on Soy and Breast Cancer Survival, and the accompanying blog post

Also see my associated blog posts for more context: Eating To Extend Our LifespanStool Size and Breast Cancer RiskBreast Cancer and Diet; and Soy and breast cancer: an update.

If you haven’t yet, you can subscribe to my videos for free by clicking here.

11 responses to “Soy & Breast Cancer

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  1. I appreciate the fact that you have raised how researchers are still using animals for studies that have no applicability to human health. It boggles my mind, as I thought the research community was required to look at alternatives to using animals for research, assessing whether there is a human benefit or need for the research on animals, having to pass by an ethics review panel and having to exam opportunities to minimize the number of animals used for the study. I am shocked that this irrelevant research continues as it does.

  2. There’s so much contradictory information out there, I would like to know your take on this quote that I found in an email I received from foodrenegade.com: “These days, people turn to soy milk. Even if you’re not turned off by the fact that it’s an industrial waste product spun by marketers into a so-called “health food,” you can’t like the numerous health-risks associated with soy. (I’ll be writing more on those later in the week. But as a foretaste of things to come, soy: is thyroid suppressing, blocks absorption of minerals like calcium, causes hormonal imbalance leading to infertility and breast cancer, disrupts protein digestion, can cause growth problems in children).”

  3. When reading claims on other websites I would tend to discount the claims unless they cite references with links to abstracts(and articles when free) like nutritionfacts.org. Even then the studies can be misleading see http://nutritionfacts.org/videos/does-tofu-cause-dementia/. Alot of misinformation about soy exists including fertility in males see http://nutritionfacts.org/videos/soy-hormones-male-infertility/; the issue re: thyroid and soy … Dr. Greger addressed in a 8/24/11 response… “Soy does indeed have so-called “goitrogenic” compounds (as does broccoli-family vegetables and flax seeds), which can interfere with thyroid function in people with marginal iodine intake. The answer is not to avoid these super healthy foods but to just make sure you get enough iodine”. See his video on Avoiding Iodine Deficiency.. http://nutritionfacts.org/videos/avoiding-iodine-deficiency-2/. Soy seems to have benefits compared to standard american diet as far as hormones are concerned see http://nutritionfacts.org/videos/the-effect-of-soy-on-precocious-puberty/ and http://nutritionfacts.org/videos/dairy-sexual-precocity/. As far as calcium absorption of soy vs cow’s milk see http://nutritionfacts.org/videos/calcium-absorption-soy-milk-versus-cow-milk/. Calf’s milk has calcium but comes with negative factors see http://nutritionfacts.org/video/plant-vs-cow-calcium-2/. Soy appears to be fine based on the science but stay tuned as the science is changing all the time.

  4. I would have to disagree with this report because in the US we use a cheap soy – not the fermented soy used in Asian countries.  When my cousin had breast cancer her oncologist actually ranted some about soy products as she was the third or fourth young women he had seen that day with estrogen related breast cancer.  She ate soy products, health food bars, and soy milk thinking they were healthy.  I won’t touch soy products except on occasion or if natural.  I use coconut milk as I’m allergic to milk.

    1. Hello Lois,
      Unfortunately, the evidence for or against use of soy doesn’t point in one clear direction. What’s known is that all foods, including soy, are complex and can be beneficial for many people in many situations, but can be harmful to others when consumed excessively. According to the National Institutes of Health (http://www.nlm.nih.gov/medlineplus/ency/article/007204.htm), for individuals who are not allergic to soy, no serious short-term or long-term side effects have been reported from eating soy foods. There are, however, several benefits to including soy in your diet. Again from the NIH, there are several scientific studies that conclude soy can lower cholesterol (http://jn.nutrition.org/content/128/2/209.short). In fact, the U.S. Food and Drug Administration (FDA) agreed that 25 grams per day of soy protein, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease (http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr;sid=502078d8634923edc695b394a357d189;rgn=div8;view=text;node=21%3A2.0.1.1.2.5.1.13;idno=21;cc=ecfr). Soy may also reduce symptoms of menopause (http://journals.lww.com/menopausejournal/Abstract/2004/11030/Beneficial_effect_of_soy_isoflavones_on_bone.4.aspx) and the risk of osteoporosis (http://journals.lww.com/menopausejournal/Abstract/2001/09000/Dietary_inclusion_of_whole_soy_foods_results_in.15.aspx). As discussed in the video, there is also some evidence that soy may prevent certain hormone-dependent cancers, including breast cancer, endometrial cancer, and prostate cancer.

  5. Hi Dr. Greger,

    So soy has been shown to have benefits for women, but what about men?
    Surely those phyto-estrogens could create problems, like gynecomastia?

    Thanks Dr.,

    Mark

    1. Hello Lois,

      Unfortunately,
      the evidence for or against use of
      soy doesn’t point in one clear direction. What’s known is that all
      foods, including soy, are complex and can be beneficial for many people
      in many situations, but can be harmful to others when consumed
      excessively. According to the National Institutes of Health
      (http://www.nlm.nih.gov/medlineplus/ency/article/007204.htm), for
      individuals who are not allergic to soy, no serious short-term or
      long-term side effects have been reported from eating soy foods. There
      are, however, several benefits to including soy in your diet. Again
      from the NIH, there are several scientific studies that conclude soy can
      lower cholesterol (http://jn.nutrition.org/content/128/2/209.short). In
      fact, the U.S. Food and Drug Administration (FDA) agreed that 25 grams
      per day of soy protein, as part of a diet low in saturated fat and
      cholesterol, may reduce the risk of heart disease
      (http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr;sid=502078d8634923edc695b394a357d189;rgn=div8;view=text;node=21%3A2.0.1.1.2.5.1.13;idno=21;cc=ecfr).
      Soy may also reduce symptoms of menopause
      (http://journals.lww.com/menopausejournal/Abstract/2004/11030/Beneficial_effect_of_soy_isoflavones_on_bone.4.aspx)
      and the risk of
      osteoporosis(http://journals.lww.com/menopausejournal/Abstract/2001/09000/Dietary_inclusion_of_whole_soy_foods_results_in.15.aspx).
      As discussed in the video, there is also some evidence that soy may
      prevent certain hormone-dependent cancers, including breast cancer,
      endometrial cancer, and prostate cancer.

  6. what about soy and estrogen hormone in men exercising actively in the gym targeting muscle building and fat loss? thanks…

  7. Hi, I have been researching about soy milk, whether it is harmful or beneficial. And i came across lots of information about harmful effects. Dr Marcola is one of them. http://articles.mercola.com/sites/articles/archive/2010/12/04/soy-dangers-summarized.aspx I am so confused. They say, traditionally fermented soy products are okey but non-fermented soy products are toxic. I am Japanese who lived there for 37 years enjoyed eating non-fermented soy products regularly (plain tofu, baked tofu, fried tofu、dried tofu…we have a variety of tofu products and each product is used for different type of dishes traditionally….and ). The western people think tofu is that white square stuff but we have more varieties and it is not unusual eating them almost everyday? We have been eating tofu for hundreds of years???(perhaps from the 7th centuries?) I just don’t get it. I use non-GM soya milk for my smoothies everyday so I am consuming probably 300ml everyday in average…and I am not eating these different types of tofu products now? Am I going to become sick because of taking non-fermented food everyday??????

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