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Breast Cancer Survival and Soy

In my two recent posts The Best Detox and Breast Cancer Stem Cells vs. Broccoli, I documented ways to 1) boost our liver’s ability to clear carcinogens, 2) make our DNA more resistant to toxins that make it past our first line of defense, and 3) then ramp up immune surveillance of any budding tumors—all in hopes of preventing cancer. But what about for those who already have it?

Though small consolation, one consequence of the fact that breast cancer is now the #1 cancer killer of young women is that breast cancer survival is a very active area of research. For example, a major study was recently published that followed 4,000 women with breast cancer for 7 years. Not all of them made it to the end. The researchers tried to figure out if there was anything about the diets of the non-survivors that may have played a role in their deaths. Two dietary components in particular were associated with an early death: saturated fat and trans fat.

Breast cancer survivors may decrease their risk of dying by 41% simply by avoiding saturated fat, found primarily in the American diet in cheese, chicken, and junk food (see my 3-minute video Breast Cancer Survival, Butterfat, and Chicken). And breast cancer survivors may improve their survival 78% by avoiding trans fat, found primarily in junk food and animal products (see my 1-minute video Breast Cancer Survival and Trans Fat). Ideally, everyone should try to minimize the intake of both, as explained in Trans Fat, Saturated Fat and Cholesterol: Tolerable Upper Intake of Zero.

On the other hand, the two foods expected to improve breast cancer survival are flax seeds and soy products. Breast cancer is initially so slow-growing that women may have tumors for years or even decades before they’re diagnosed (see my 1-minute video Cancer Prevention and Treatment May Be the Same Thing). So one might expect that the same dietary factors that helped grow the tumor in the first place would keep goading it on after diagnosis. This may not always be the case, though. Alcohol, for example, is strongly associated with breast cancer risk, but the data has been mixed as to whether once you already have a full-blown tumor, it makes a difference if you continue to drink or not. Still, in general, the diet that helps prevent breast cancer is the same diet that’s going to help prolong survival. And that certainly seems to be the case for the phytonutrients found in flax and soy.

Flax seeds are the most concentrated source of lignans, a class of cancer-fighting compounds that may cut breast cancer mortality risk in half (see my 3-minute video Breast Cancer Survival and Lignan Intake). Interestingly, there are no lignans actually found in the seeds, just precursors that the good bacteria in our gut turn into lignans. This may explain why women who have frequent urinary tract infections have higher breast cancer rates—the courses of antibiotics wipe out the gut flora critical to the production of these anti-cancer compounds (see my 2-minute Flax and Fecal Flora).

Soy foods appear to help prevent breast cancer and prolong survival more directly, though. In Breast Cancer Survival and Soy I review the only three human studies to date, all of which suggest soy is beneficial. Before we had any human data, rodent studies found conflicting results, and we just found out why. It turns out rats and mice metabolize the phytoestrogens in soy up to 150 times less efficiently than humans. The faulty old lab rat data continue to be cited by soy detractors, however, even though we now have studies published on thousands of actual breast cancer survivors. While the jury may still be out on whether to feed tofu to your pet rat, the verdict is in on soy in human beings: not guilty.

-Michael Greger, M.D.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

4 responses to “Breast Cancer Survival and Soy

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  1. So glad you discovered the site! Would you mind posting your question to the relevant video comment section? ( ) Or if there’s not video that matches, just under one of my Q&A blogs. That way everyone could benefit (I’m sure there’s lots of people who have the same types of questions–thanks!)

    In health,
    Michael Greger, M.D.

    On Oct 3, 2012, at 7:03 , wrote:

    Dear Sir,

    You give me HOPE!  Really? A Doctor that makes since?!  Just when I have been loosing all HOPE, lose hope, and its over….

    Can you send me any studies/info, your opinion on how to dissolve uterine fibroids in the lining?  Supposedly there are (6), one the size of grapefruit and the rest to equal a uterus the size of 5 month pregnancy.  I have not had an ultra sound now for three years, so i don’t know the exact size of uterus now, but I can palpitate and know they are still there.  I have been vegan and more than 70-90% raw, organic, for 6 years.  I survived mercury/metal poisoning, still living with anemia, but the last three months I am starting to get energy and oxygenation in my muscles, my heart and lungs!  I don’t cry going up a flight of stairs!  Today, I rode, 4 miles on my bike without stopping the pedaling!  This is so BIG for me I cant tell you!  

    Next month I will be 53, still no signs of menopause except in my level of patience with cutting out the b.s. in my life!  My menstrual periods have been so heavy for 18 years, 8 days, 3-4 days of hemorraging basically.  Present day, I have a strong period every 23 days, only 2 of the 6 days are heavy, (yet I can get through the night with a super sanitary pad) nothing hemorraging like they were in the past.  Still, I have some smaller clots on day three with some fibrous material discharged in the blood but bleeding is getting lighter each period.  Is this the fibroids breaking down or is this a lack of progesterone?  I have also heard progesterone creams can make fibroids grow…I have heard it all, this/that.  I just want to make the right environment for my uterus to heal…  I have lived mostly vegetarian for 30 years, 6 of these last years have been vegan, 70-90% RAW, LOTS OF GREENS YET HIGH in GOOD FATS, low glycimic, Gabril Cousens work.  NOW SINCE DEC 2011, I HAVE BEEN MOVING INTO Douglas Graham’s 80/10/10 LIFE STYLE WITH SOME LIGHTLY COOKED FOOD,  80-95% raw, and of course organic.  This summer on the high fruit, I have felt the best ever that I can remember feeling in my LIFE on this life style and these fibroids do not fit in with how I am mentally and physically feeling these days!  This high fruit/low fat, mostly raw diet is really starting to make positive changes!  I mean after that bike ride the other day, I said, with hope and tears in my eyes, “HOLY CRAP! SOMETHING IS CHANGING”!

    My blood is bright and healthy but still to much is released each month for me to get my iron caught up to correct levels!  HELP!

    Hear are the blood test values that were outside of normal ranges from a low income health screening i had done 3/4 months ago.  
    Note: This summer has been a very successful 811rv summer and I will not have test done again till april 2013.  L represents, LOW.
    ferritin serum raised to 3 L, it was below 1 the following year, iron serum 13 L, % saturation 3 L, hemoglobin 9.1 L, hemocrit 29.8 L, MCV 67.9 L, MCH 20.7 L, MCHC 30.5 L, RDW 20.0 (high), urea nitrogen, serum 5 L,  A/G ratio 2.2 (high), globulin 2.0 L, cholesterol, serum 120 L, for a vegan is that low or is this really, good?  The naturual path says it should be 140 for my hormones to work correctly, then why do so many people have heart attacks with fine levels of this 125-200 reading?)   

    I can not afford medical doctors nor would i like any more of their opinions of going on dangerous, exspensive, horrendous side effect pharmaceuticals to stop my periods for three months to get my ferritin levels up so then they can do a $25,000 surgery to take my precious uterus that gave birth to my three lovely grown daughters!  Their scare tactics about cancer and such I have no interest in, nor their continued suggestions of more ultra sounds, (o just $400 a pop and more radiation in my body)…..
    You Sir, actually sound like a Doctor who has some knowledge about helping people not just making more complications out of a situation!  I am in the prime of my life and in a deep, wonderfully spiritually sexual relationship for the past 9 years, a yogini for 28 years, a mostly raw veganfor 6 years and now… on this fruit path!  Need I say more….my sexuality is out the roof and the last thing I want is that taken away from me by removing my uterus!  GRANDMA mod… i have no interest in this lifestyle at this time!  Where do these doctors get off on suggesting such madness!  Is it just for the money?  Do they really believe their story?  

    You give me HOPE!!!

    The reality is, I am TIRED/EXHAUSTED of dealing with these fibroids.  I have promised my self to wait this out till I go through the change, as my research tells me these fibroids will probably dissolve or reduce to small, once my periods are over… I here some raw foody’s will have periods up into there 60’s!  Truthfully-I just cant mentally, nor physically take seeing and feeling this amount of blood coming out of me every 23 days, watching my face loose its magnetism from all the years of low iron, breaks my heart.  I live in a small ranching mountain town in Colorado with doctors that believe in meat and i will have nothing to do with their madness and their pharmaceuticals.  I feel you may be of help, I am begging for any insights you may have.  

    Thank God the 28 years of Iyengar Yoga has kept the fibroid uterus from adhering to organs as far as I know and when it effects my bowels i can adjust in upside down poses, mainly the plow pose is most effective for manual manipulation.  One other piece, the uterus is retroverted and the base of it seems wedged in pelvic cavity. I do get pressure on my bladder but can deal with this side effect.  Also I do drink a half to one cup of coffee per day, (an emotional addiction, that always re-enters my life) I can not belive this small addiction has kept the fibroid from dissolving….I am ready to deal with this emotion now and will stop tomarrow if you say I have to…..

    How do you feel about trying a strong mitake mushroom regime?  What would be the amount to take?  I have heard this can dissolve uterine fibroids.  Dissolve what?  If these fibroids were removed and tested, what would be in them besides fiberous material?  Mercury, pesticides, estrogens from the enviroment, being on birth control pills from 15-22 years old, an undeveloped pregnancy, a hpv virus, a dysfunctional childhood, standard american diet up till i was 22, never being nursed, all the dairy and meat during childhood, PBC’s or all of the above?   What are these freaky fibroid aliens that wont leave my body that is rebuilding itself through VEGAN plant based diet?…  Is the next step FASTING?

    I beg for some answers, some truths and help.  You have the mind and since of humor I have been digging for!!!!

    Thank you for your time Sir….After seeing you for the first time on you tube, on the 15 diseases, I heard my soul say,  “I want to work with, for – this man”.  I have HOPE!
    with great respect for your work,
    very sincerely,

    Brenda Flemming

  2. This article is misleading…I cannot believe this article has recommended women to consume soy milk as a preventative for breast cancer. Truth is – soy INCREASES estrogen in a woman’s body, and it has been proven that excess estrogen unbalances a woman’s estrogen/progesterone and EXCESS estrogen is the harbinger of breast cancer. Stay away from the soy milk and soy products (which is in almost every food product on the market today). This is what I learned from being estrogen dominant myself. AND natural progesterone (NOT Depo-Provera, the synthetic progesterone crap) does a woman any good. Too many young women are using too many synthetic hormones prescribed by their ignorant doctors…

    1. Nonsense. The so-called “phyto-oestrogens” in soy are actually phytoSERM, i.e. modulators of oestrogenic activity. The bind to estrogen receptors instead of oestrogens and thus they reduce the exposure to endogenous oestrogens and protect against breast cancer.

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