Soy for Hot Flashes? Read This First

PJ Hamel Health Guide
  • Do you take an aromatase inhibitor (Femara, Arimidex, Aromasin) to prevent breast cancer recurrence? Do you also take one of those “all-natural” dietary supplements that’s supposed to deal with menopausal symptoms—particularly hot flashes? If so, you might want to reconsider how much that hot-flash relief is worth to you.


    About two-thirds of all breast cancer cases diagnosed in the U.S. are estrogen-sensitive. If you have breast cancer, you probably saw “ER/PR+” or “ER/PR-” on your pathology report, among all the other confusing acronyms, numbers, and symbols. “ER/PR+” means your particular cancer relies on estrogen and/or progesterone to grow; a minus sign means you’re in the minority whose cancer doesn’t depend on estrogen.

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    So, let’s say you’re ER/PR+, you’ve had your active treatment (surgery, chemo, radiation, et. al.), and now your oncologist says you’ll be taking hormone therapy. You’ve been through menopause; maybe naturally, or maybe as a result of chemo or surgery. Your doctor recommends you take an aromatase inhibitor (AI), a class of drugs that prevents your body from manufacturing estrogen, thus depriving cancer cells of their nourishment. 

    You start taking Aromasin, or Femara, or Arimidex. So far, so good; die, cancer, die! But, as a result of menopause—or as a side effect of the drug itself—you’re having wicked hot flashes, heat that seems to explode from your midsection, leaving you feeling like you’re Joan of Arc at the stake as you run to stick your head in the freezer. Heat that awakens you from a deep sleep, sends the bedclothes flying around the room, and leaves you shivering on a sweat-soaked sheet. Hot flashes are discouraging, aggravating, and just plain miserable. What’s a girl to do?

    Not much, according to any doctor I’ve ever asked. You can try vitamin E; black cohosh; an anti-depressant drug…I’ve had bothersome hot flashes, and I’ve tried all three of those remedies; none of them worked. Then I thought, well, how about those over-the-counter remedies I see on the bottom shelf at CVS? “Treat hot flashes the natural way.” Why not? I’ve got nothing to lose.

    I’d just put “menopause relief” on my shopping list, when I ran across an online article reporting that soy isoflavones (one of the main ingredients in natural menopause-relief supplements) had been accused of some pretty serious stuff:

    They prevent AIs from doing their work.

    A study on the subject, released last month, focuses on Femara, one of the Big Three AIs. Researchers at universities in Illinois and Virginia, conducting several mouse-model trials, have shown that tumors were effectively stopped from growing when treated with letrozole (the generic form of Femara). Then, when a certain soy isoflavone—genistein—was added to the mix, those tumors actually started to grow again.



    Genistein is a common ingredient in over-the-counter hot-flash remedies. So you take a soy-based remedy for hot flashes, and you neutralize the drug that you’re hoping will prevent your cancer from returning. Not good.

  • Let’s hear from Dr. William Helferich of the University of Illinois, the study’s principal investigator:

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    “To think that a dietary supplement could actually reverse the effects of a very effective drug is contrary to much of the perceived benefits of soy isoflavones, and unsettling. You have women who are taking these supplements to ameliorate post-menopausal symptoms and assuming they are as safe as consuming a calcium pill or a B vitamin.

    “These compounds have complex biological activities that are not fully understood. Dietary supplements containing soy-based phytoestrogens provide high enough dosages that it could be a significant issue to breast cancer patients and survivors.”

    Concluded Helferich, “These findings raise serious concerns about the potential interaction of estrogenic dietary supplements with current breast cancer therapies.”

    Translation: Take the hot flash remedy, you’re potentially opening the door for a breast cancer recurrence.

    WHOA. I eat a ton of tofu; use soy milk occasionally, enjoy soy nuts… Does this mean soy’s just not good for breast cancer survivors, period?

    Thankfully, no. Helferich adds that his research shows that soy itself, rather than its extracted isoflavones, does NOT make tumors grow. “When the whole food is consumed you get a very different effect than if you consume the concentrated constituents individually. The whole soybean is healthier than many of its individual chemical parts,” he concludes.

    So keep the tofu and soy milk; ditch the all-natural menopause relief. Sorry, gals; we’re just going to have to keep the ice pack and dry bedding handy till the researchers finally come up with something that’ll cool us down WITHOUT encouraging cancer.

Published On: November 02, 2008