Soy Fights Breast Cancer?

Over the years I have heard many ladies say they avoid Soy due to it being bad for breast cancer prevention or for those who currently have or had breast cancer. I’ve also received many alerts from my go-to education sources citing the opposite, that it prevents prior and post occurrence. Why is there this discrepancy? With all things I’ve learned about my own health, I go to the sources of the information and it leads to a typical answer.

For Soy, I found a lot of great information from Dr. Michael Greger and (links to his findings included below). He is one of my go-to resources on all things health and for breast cancer, I cite him and other sources I trust in my previous breast cancer awareness blogs you can find at the bottom of this edition.

Let’s get back to this Soy business…

Why is Soy Beneficial?

  • Soy turns BRCA genes on. BRCA genes, also called caretaker genes, are cancer-suppressing responsible for DNA repair.
  • Who Shouldn’t Eat Soy? “The original theory for how soy phytoestrogens control breast cancer growth is that they compete with our own estrogens for binding to the estrogen receptor. As you drip more and more soy compounds on breast cancer cells in a petri dish, less and less actual estrogen is able to bind to them. So, the estrogen-blocking ability of phytoestrogens can help explain their anti-estrogenic effects.”
  • Is Soy Healthy for Breast Cancer Survivors? “People don’t realize there are two types of estrogen receptors in the body—alpha and beta. And, unlike actual estrogen, soy phytoestrogens ‘preferentially bind to and activate [estrogen receptor beta]. This distinction is important, because the 2 [types of receptors] have different tissue distributions…and often function differently, and sometimes in opposite ways.’ And, this appears to be the case in the breast, where beta activation has an anti-estrogenic effect, inhibiting the growth-promoting effects of actual estrogen—something we’ve known for more than ten years. There’s no excuse anymore.”


  • Breast Cancer Survival and Soy
    • Study 1 – About 2,000 California breast cancer survivors followed for nine years. Postmenopausal women, on the estrogen–blocking drug tamoxifen, who got the most of this soy isoflavone in their diet had the lowest rate of breast cancer recurrence—appeared to cut breast cancer recurrence in half. Soy was, if anything, protective. 
    • Study 2 Journal of the American Medical Association study, the biggest yet—5,000 breast cancer survivors. Conclusion: “Among women with breast cancer, soy food consumption was significantly associated with decreased risk of death and recurrence.”
    • Study 3 – 2011: “Soy Food Consumption and Breast Cancer Prognosis.” A third study—the only three such studies in existence—and soy is three for three. “As isoflavone intake increased, risk of death decreased.” What more do we need to know?

It’s interesting how myths are formed like. ‘where do those eating a plant-based diet get their protein?’ Another myth I share in a previous blog, The Protein Myths. Unfortunately breast cancer and other cancer route causes from animal consumption seem not to get a lot of attention. This is what I have found digging around. Like anything else concerning our health, consult with a physician, find resources you trust, and educate yourself to make informed decisions.

– Add Health to Your Life

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