Should I stay away from soy if I have breast cancer?

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Should I stay away from soy if I have breast cancer?

I am now confused. I was told by my oncologist and internist to stay away from soy after I was diagnosed with breast cancer. My tumor was estrogen positive and I was told that soy mimics (or something to that affect) estrogen. It is very upsetting to have such contradictory information.

Kleuna/Originally Posted in BRCA Breast Cancer Genes and Soy

Answer: Sorry to hear you are facing such contradictory statements, let alone dealing with breast cancer, how frustrating!

I believe the best evidence we have to date shows whole soy foods like tempeh, edamame, and even tofu are safe, even for women with estrogen receptor positive breast cancer, according to two recent studies. Dr. Greger has so much great info about soy. It is important to listen to your doctor and follow her or his advice. I suggest relaying any information you receive about soy with your health care team.

Lastly, I wanted to point out that large cancer organizations like the American Cancer Society and the American Institute for Cancer Research also have a position on soy. These organizations say, 2-3 servings of whole soy foods per day are safe, and even healthful. Whole-soy sources include: tofu, tempeh, miso, and edamame.

Please let me know if there’s anything else I or Dr. Greger can do to help you through this difficult time!

Image credit: cyclonebill / Flickr


20 responses to “Should I stay away from soy if I have breast cancer?

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  1. Soon after I added soy and edamame to my diet, I not only began experiencing stomach cramps and hideous, sulfur-ish belches that would literally clear a room. I did not realize my problem. I went to the doctor who immediately put me on medication for GURD. My diet did not change, nor did my symptoms subside. It was not until I was reading about my Latex allergy that I learned that latex contains soy. I eliminated soy from my diet and I was soon discomfort free. To further this experiment (and because of soy bean cravings) I tried eating liberal amounts more than six months later and…yes, the symptoms returned. Have there been any studies connecting latex and soy?

    1. Seems you have a problem with digestion. When we have eaten cooked foods for most of our lives and then began eating raw foods the body may need digestive enzymes to help digest foods until restoration is obtained.

  2. Everyone should be careful about loading up on too much of one food. Your body likes variety and you shouldn’t be munching on soy beans everyday. There are plenty of beans you are missing out on. Pinto Mondays, black bean Tuesdays, kidney bean Wednesdays, Lima bean Thursdays, black eyed bean Friday, soy bean Saturday, chick pea Sunday. That’s how I do it.

  3. I too am very confused with the topic of soy! I l was told to read the article on the Dr. Mercola website about soy. He says that unless the soy is fermented, we should not be consuming it. Right now I buy organic tofu and use it as an “egg” scramble, I make appetizers with it and use it in other recipes. I am concerned that with 2 teenagers, I should be more cautious. With so many different opinions on this subject, it is difficult for me to know what is the right choice.

    1. Patricia: I couldn’t agree with you more on how difficult it is to figure out these things when seemingly respected, big-name individuals tell you opposite things. When I get to this point, one of the factors I take into account is the source. How credible, how reliable is the person in general who is telling me these things?

      I’ve researched both Dr. Greger and Dr. Mercola a great deal and come to the conclusion that Dr. Mercola is not generally a reliable source of good information. I’ve heard of claims from his site about say cholesterol that are “easily” disproved. So, I am very careful about any information sourced from Dr. Mercola. (No one is right all the time and no one is wrong all the time. So, I’m sure Dr. Mercola says some things that are right.)

      One factor that is key for me is that Dr. Mercola is selling things. Dr. Mercola is making a living off of selling things. Dr. Greger is not. (Anything Dr. Greger sells or makes on speaking engagements is donated to charity.)

      You will have to decide this for yourself of course. But here are some posts from NutritionFacts community members which I found helpful: (addresses Mercola at the bottom)

  4. I am also a woman being treated for estrogen positive breast cancer. I too, have read and have been given contradictory information on soy. A dietitian recently told me that 1/3 of the population’s bodies can convert plant estrogens into actual estrogen. He said there isn’t a test to see if I am in that 1/3, so I should be careful with my consumption of soy products. Has anyone else heard or have knowledge about this?

    Yvette Smith

    1. Hi I also estrogen + BC recently estrogen + uterine cancer too – may have been caused by the BC med Tamoxifen I went off after 2 years 2 months due to side effects (1 – 3 in 1000 get uterine too). Interesting around the time of BC diagnosis my body started reacting to soy milk and tofu both of which I loved ! Surgeon said there is a difference between Western and Eastern soy usage, so fermented soy products fine. Also beware of red clover.

      1. KJ, thanks for the information. I have been on Tamoxifen for 2 yrs. and 3 months. I hope and pray it was a good choice to take it. Were your uterine cancer symptoms obvious or was it difficult to detect?

  5. I’d like to hear a video about diet for various blood types (A, B, AB, O, etc.). A few people I know feel that one’s diet should be tailored to blood type. I am skeptical, but open to the truth :-)

  6. I understand that the Fake meat/cheese type soy products from isolated soy protein are associated with higher IGF1 levels. Is this true for isolated pea proteins as well. I don’t want to mention any company names as I think their hearts are in the right place but does anyone have any science on small amounts of this in diet. Obviously whole food best and these products are processed and have other chemicals. Just wondering… any science regarding IGF1 levels and isolated pea protein yet?

    1. Hello Bonnie, I am a family doctor and a volunteer moderator for this website. I just looked up “pea protein” and “igf-1” on PubMed, and only 5 articles came up, none of which had any useful information. So, there does not appear to be any good science as yet to answer your question.
      There is quite a bit published on the topic of “soy protein” and “igf-1”, though. Look at the Discussion section of this interesting article, which says that the effects of soy on IGF-1 “are inconsistent.” In American women, soy supplements cause a significant increase in IGF-1. In Japan, tofu consumption is associated with DECREASED IGF-1 levels. Three referenced studies from Netherlands, Singapore, and China showed no association. The authors hypothesize that it could be an issue of soy powder vs. soy foods. But the bulk of this paper was about showing that seaweed consumption prevents much of the increase in IGF-1 caused by eating soy powder.
      So, as usual, it appears that we should not be using supplements, but rather should be eating plant-based foods. That’s probably a good thing to remember about peas as well, i.e. eat the whole pea, not the protein powder.
      I hope this helps, a little.

  7. I could never say enough about how much hope Dr. Greger, M.D. gives me. I came home from the surgeon and oncologist with a diagnosis of triple negative, very invasive breast cancer the usual go home and have a nice day. I went on the Internet after finding Dr. Greger and went from eating a 90% dairy and meat and as much sugar as I could a day diet to a 100% no meat based diet, no sugar or processed food and to also eating lots of Turmeric, Oregano, Green Tea because my mother passed away two years before my diagnosis from an unknown viral disorder and in a dream she told me to drink green tea. I didn’t until I got diagnosed. etc……. Hospice is not happy but I don’t care and I don’t always have the motivation to cook all the fruits and vegetables, but what I do eat is organic and ONLY plant based including use of vegan cosmetics like bath soap. Dr. Greger is an angel if only for the hope and weight he has taken off my mind. The last PET scan before Hospice showed no further metastasizing . I feel good right now. No matter the outcome, I know it will be better than if I had not discovered Dr. Greger. I want to read the except of his book and while I don’t really need reassurance about anything Dr. Greger says, I want to make sure it is more of his brilliant words ESPECIALLY ABOUT SOY and triple neg!! . There are things I still want to see and do on earth. I had a lot of years to do a lot of damage, but it is like stopping drinking poison. It will definitely do some good.

  8. Thanks for this information. I found it to be very helpful. I will stick with the whole soy food options as a good healthy choice.

  9. I cannot find a reliable source that offers an evidence based opinion on textured vegetable (or soy) protein – TVP or TSP. I love using it in my vegan chili, but a wander through the internet will turn up sites that praise or vilify its use. This is my go to webpage for nutrition facts of course. Does Dr. Greger have anything on the use of this product?

  10. Hi, Duke363. As far as I can tell, there is no research specifically about health effects of consuming TVP or TSP. In my clinical nutrition practice, I generally tend to recommend against using it as a dietary staple, because it is more processed than other soy foods such as edamame, tofu and tempeh. Incidentally, have found that crumbled tempeh works very well in vegan chili. I suspect that occasional TVP/TSP consumption is fine.
    Dr. Greger only mentions TVP (along with vegan chili) on this site once, in a passing mention that textured vegetable protein shares an abbreviation with “transurethral electrovaporization of the prostate.” Because Dr. Greger reports on research, and there does not appear to be any research on this topic, it is not featured on NutritionFacts. I wish I had more information for you, but I hope that helps!

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