Hey, Soy – Let’s Be Breast Friends Again!
Soy. That little three-letter word that strikes fear into the stomachs of so many. Why are we so afraid of soy? Well, I bet you’re asking …
What’s so great about soy?
The soybean is the only bean that is a complete protein on its own. It has lots of good stuff like phytic acid that can bind dangerous heavy metals, alpha-linolenic acid that helps control inflammation and isoflavones like genistein and daidzein that help protect your heart and bones.
Soy also contains phytoestrogens (aka plant estrogens), which are pretty similar to the estrogen formed naturally in your body. Soy has a high level of phytoestrogens, but still only has a teeny-weeny bit of the power of human estrogen – just two percent! Phytoestrogens will bind to your cells’ estrogen receptors, but oddly enough, at the same time phytoestrogens can bind up estrogen to stop it from working.
And most people don’t realize that soy is not the only plant to contain phytoestrogens. Believe it or not, over 300 plants contain them, including flax, sesame, wheat, oats, barley, beans, yams, apples, carrots and pomegranates.
Can I eat soy if I have breast cancer?
Soy can seem kinda scary if you have breast cancer that is estrogen-receptor positive (ER+). But scientists are starting to unlock this mystery of how soy works in the body with breast cancer. What they have found is that many cells in the body have estrogen receptors. Think of these receptors like little locks that need estrogen to act as the key to open them. So estrogen unlocks these doors and lets breast cancer cells grow and multiply. But phytoestrogens fit into these same locks but cannot open the doors so they wind up competing with your natural estrogen and blocking it from working!
On top of that, phytoestrogens help to prevent cancer cells from talking to each other and ganging up on you. Phytoestrogens also stop the growth of blood vessels to tumors to cut off cancer cells’ nutrition and fiddle with processes involved in DNA that mess up how cancer cells grow and multiply. Cool!
Now, if you have what is called human epidermal growth factor receptor 2 (HER-2) positive breast cancer and are on a drug called trastuzumab (Herceptin), soy may actually help trastuzumab work better. Late breaking news: Breast cancer cells treated with genistein along with trastuzumab significantly slowed breast cancer cell growth more than using just the drug alone![i] On top of that, genistein has been shown to suppress HER-2 activity!
If you are on the drug tamoxifen, then soy may help you, too. Many people on tamoxifen are told by their docs to avoid soy because tamoxifen’s job is to block those estrogen receptors, and the thinking is that tamoxifen might bind to the phytoestrogen in soy instead. But back in 2007, researchers in Israel found that genistein may actually sensitize ER+ and HER-2+- breast cancer cells to tamoxifen and help it work better. Genistein and tamoxifen together caused breast cancer cells to self-destruct by targeting receptors on the cell surface and telling them to stop making something called “survivin,” which, you guessed it, helps cancer cells survive and ignore signals to self-destruct.[ii]
What if I’m a breast cancer survivor?
First of all, congrats for making it through a long and difficult journey! And to reward you, you can add soy to your diet, too! In 2009, results from a study of over 5,000 Chinese breast cancer survivors stated that women who consumed three cups of soy milk per day were less likely to have a recurrence or to die of breast cancer than women who only drank ½ cup a day![iii] And last month, researchers found that the risk of recurrence for postmenopausal breast cancer survivors was 33 percent lower for Chinese women who ate more than 42 mg/day of isoflavones – that’s only ¼ cup tofu a day! And they found this was especially true for women with ER+ breast cancer and who were taking anastrozole (Arimidex).[iv] Okay, yes, these were all Chinese women who grew up eating soy. But we could learn a lesson from them. What makes a big difference is the type of soy that’s eaten, and that we actually eat it! Read on …
What kinds of soy should I eat?
Definitely choose organically grown soy, which by definition means that it will also be what is called “non-GMO” (non-genetically modified organism). Genetically modified (GM) soy is scary! Over 90 percent of soy grown in the United States is modified genetically to be resistant to herbicides sprayed on fields to kill off weeds. As a result, GM soy is now contained in up to 70 percent of all food products including cereals, pasta, breads and even meat since animals are fed GM soy as part of their feed to help them grow faster. GM soy has been linked to allergies, birth defects, infertility and cell mutations in the liver and pancreas. Yikes!
Also be sure to get the least processed forms of soy in your diet: edamame, soy nuts, soy milk or tofu. And by all means, experiment with fermented soy options like tempeh, miso, tamari soy sauce or natto. If you’re still scared of soy, it’s good to know that fermenting soy lowers the phytoestrogen content found in soy. Since some of the carbohydrates in soy are broken down during fermentation that means less jet propulsion from gas. Bonus!
But that doesn’t mean all you eat is soy, soy, soy each day. Make sure you get a variety of beans, legumes, nuts and grains in your diet each day to round out your protein intake. Based on the studies out there right now, you should aim to get at least one serving of soy each day – that’s ¼ cup of tofu or tempeh, one cup of soy milk or a small handful of soy nuts. Get your soy on!
Photo credit: Dayna McIsaac
[i] Lattrich C, Lubig J, Springwald A, et al. Additive effects of trastuzumab and genistein on human breast cancer cells. Anticancer Drugs. 2010 Dec 14. [Epub ahead of print]
[ii] Mai Z, Blackburn GL, Zhou JR. Genistein sensitizes inhibitory effect of tamoxifen on the growth of estrogen receptor-positive and HER2-overexpressing human breast cancer cells. Mol Carcinog. 2007;46(7):534-542.
[iii] Shu XO, Zheng Y, Cai H, et al. Soy Food Intake and Breast Cancer Survival. JAMA. 2009;302(22):2437-2443.
[iv] Kang X, Zhang Q, Wang S, et al. Effect of soy isoflavones on breast cancer recurrence and death for patients receiving adjuvant endocrine therapy. Can Med Assoc J. 2010;182(17):1857-1862.
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22 Comments
I’ve stopped eating soy and experienced huge changes. I suffer from fibroids and endometriosis. Nearly every month my stomach would blow up and I would bleed a lot. Since I heard that people who are have estrogen related illnesses should stop eating soy, I decided to eliminate it. My fibroids aren’t becoming irritated every month and I really do think the soy has something to do with it. I don’t have scientific evidence to support this but I think people who have estrogen dominant issues should stay away from soy, dairy and meat.
I am sorry but Soy??? Not for me, not for my family for a million different reasons.
Cassandra! I would love to learn more about the positive effects you have had limiting soy. I have endometriosis and I have heard that eliminating soy can be beneficial, but since I am a vegan, I am not sure if that is such a great idea. Do you have any research or articles you can share?
Amen! The fear around soy is so prevalent and I think that for most people, organic and whole soy products are a wonderful addition to the diet. I experiences Surgical Menopause at the age of 23 due to large tumors having to be removed and soy has been a very important part of my diet to help control menopausal symptoms.
I have read studies but it’s been a while since I read them so I can’t point you to a specific one. If you Google some of the websites related to endometriosis and food many of them recommend that you abstain from soy, however Dr. Andrew Weil believes soy is okay in cases of endometriosis. In Crazy Sexy Diet Kris warns that it may not be good for those who have uterine and ovarian caner because the isoflavones could promote the growth of the disease. Since I too ate vegan and only ate organic soy, I felt crappy about having to give it up but I suspected it was too estrogenic for me. Try leaving it out of your diet for a month and see if you notice any difference.
Sorry to hog the discussion and add another comment. If I was too low in estrogen or going through menopause I would probably add soy back in my diet. But when you’re vegan and estrogen sensitive I think we tend to eat more soy than we should which is why may end up having problems with it.
What if you have hypothyroidism? Any thoughts on that?
Soy blocks the uptake of medications given to hypothyroid folks. No more than 4oz a week can be consumed. That’s what I’ve been told by various people who have the condition.
I’m a huge supporter of soy in our diets, I buy only organically raised products. I’ve been vegetarian for years and just switch to vegan, I can’t imagine life without it!!
Not for me – I’m a soy-free whole foods vegan. I avoid anything with “soy protein isolate” in it – I also avoid legumes generally since my body does not like them (anyone else end up with flu symptoms from legumes? nausea, lethargy to just going to sleep?)
Does anyone know of any brands or websites where you can buy these non GM Soy products?
“One of the healthiest changes you can make to your diet is to incorporate whole organic soy foods on a regular basis” Dr.Weil
Studies of the elder Okinawans, who include lots of soy foods in their diet, show that breast and prostate cancer is exceedingly rare in that population. The elder Okinawans’ diet is also overwhelmingly plant-based.
In Japan dry roasted soynuts ( iri-mame ^) are extremely popular, they are also called fuku-mame ^ or “beans of good fortune”
Both the FDA and the American Heart Association encourage eating at least 1 oz (28 grams) of organic soy daily. That’s about 152 soy nuts
High soy intake during adolescence reduces the risk of breast cancer in the pre-menopausal years by about 25 to 50 percent, new study
There are a few organic soy farmers(10%) still working very hard in the US… Only consumers have the power to change the world!
Great article Jacki you really did your research!
Thank you for a wonderful article including current research! It’s really unfortunate to see all those other articles popping up with biased obsolete research funded by the Weston Price Foundation (working in favor of the dairy industry). So thank you for finally helping debunk some of those myths! Agreed that when eating soy it should be from a less process source (eating the products that could be made in a home kitchen). The products that can’t be made in your kitchen should be passed on: soy protein isolates, soy oil. That is true for any food product…high fructose corn syrup anyone?
Non-GMO’s are different from Organic so you should always look for both Organic and non-GMO soy. For Mat: here’s a handy shopping guide: http://www.nongmoshoppingguide.com/
Wow, I didn’t know soy was that beneficial! I’ve only heard that it’s BAD for estrogen balance. It’s great to know the real story!
I’m curious now – how does soy affect hormone balance for taking care of things like menstrual cramps, acne and other hormone-related stuff? Have any advice on that part of the whole hormone story?
I have read many articles and research reports on soy over many years, and a very common theme states that fermented soy is the only safe soy. It seems to me the one thing that many exponents of soy don’t mention is that all the regions that exhibit healthy lives and consume substantial amounts of soy (Okinawans, for example) largely consume fermented soy products, rather than less refined versions.
It is also dangerous to quote such things in such a general way, as the whole diet of these people also has a large impact on their general well-being and it is risky to conclude that one part of that diet is the cause of their longevity.
Excellent info. I’m always having to stand up for soy. Many people seem so inadequately educated about soy.
Gerson says is soy not good! I like Gerson.
Wow this is an interesting post. I do believe soy has lots of good stuff but at least for me, anytime it enters my body i feel like im in a warzone. I dont tolerate it or its affects at all and whatever good stuff is in soy i dont think survives the battle…. : /
Everything in moderation? Personally, making sure the things I eat are simple, unprocessed (as little as possible), organic, non-GMO (take a hike Monsanto), mostly raw and vegan have gotten me away from insulin-dependent diabetes, serious daily heartburn, and rosacea. My hair is almost completely blonde again (49 this week with almost NO gray). I too am trying to figure out which types and how much of things to consume, so I think we all have a bit of research and responsibility to perform on ourselves and our families. I can’t eat any legumes without digestion consequences, but my partner can eat them all the time with no problems. Dairy and processed foods evidently significantly contributed to her ovarian cysts. We now eat some non-GMO miso and nama shoyu without problems. But moderation I think is still key, I could eat raw brownies with banana ice cream every meal (instead of salad), but my body tells me that it works best on GREENS! MORE FRESH RAW GREENS, PLEASE!
Hi everyone — thanks so much for all of your interesting comments! I knew this topic would open up a good debate!
Soy – you either love it or you hate it. It is not for everyone. No food is. Some people are sensitive or downright allergic to certain foods, so if soy is a trigger for you, then definitely stay away! Remember guys, isoflavones are in a ton of foods – soy just happens to top the list. If soy is not your thing, then try flax or other foods on the list above.
@Cassandra — There’s not a lot of data out there on soy and enodmetriosis but what I did see suggests that soy can reduce the RISK of endometriosis but no data says soy can treat it. In fact, I did see one case study that linked soy isoflavone supplementation to development of endometriosis. I do not recommend soy supplements, just natural organically grown soy. And you are correct – when you are vegan you usually gravitate towards soy products since they are now everywhere. Be sure to get protein from a variety of sources including beans, grains, and veggies. Oh, and nutritional yeast – fantastic as a cheese sub and a good source of protein to boot.
@Kristine — Want the good news or the bad news for people with thyroid issues? Well, a randomized, double-blind, crossover study published last month showed that the bad news is there is a 3-fold increased risk of developing overt hypothyroidism with dietary supplementation of 16 mg soy phytoestrogens with subclinical hypothyroidism. However, good news — 16-mg soy phytoestrogen supplementation significantly reduces the insulin resistance, hsCRP, and blood pressure in these people.
@Mat — Look for organic soy products like Nasoya, Lightlife, and Eden Foods – just to name a couple. And thanks Jess for your handy dandy website!!
@Kristin — A quick search of the latest studies through PubMed.com showed that genestein can indeed slow or stop growth of cervical cancer cells. Same goes for uterine and endometrial cancer. Genestein slows inflammation due to cytokine production from ovarian cancer cells and helps them to stop growing.
@Seamist — I agree! I love greens! In fact, I am craving kale chips right now… And cruciferous veggies (broccoli, cauliflower, cabbage, Brussels sprouts…) get a high mark on my list of veggies to recommend for anyone battling or surviving breast cancer due to their high indole content.
Veggies = Vitality!
Jacki
Are you absolutely sure that this is true:
“Definitely choose organically grown soy, which by definition means that it will also be what is called “non-GMO” (non-genetically modified organism). ”
I had done some research for a different topic a few weeks ago and found that just because something says organic (seed I was buying for my garden) did *not* necessarily mean it was non-GMO, and vice versa.
WOW!!! Great discussion peeps! I found this site looking to see if Breast Cancer that were Hormone Receptor Positive could take Non GMO Soy- being the isoflavons and estrogen have been removed from them. I have a friend that just started taking the shakes I am using to help her with health issues and weight lose and she had lost 5 pounds in her first week. She went to her doc in TN at Vanderbilt and she told her not to take them anymore because she was hormone receptor positive. I am confused. I have docs saying its great for you and docs saying it isn’t. UGH!!! I was so excited about being able to help her out with health issues etc and now she is disappointed cause we were both so excited about it and she was doing well. I have lost 35 lbs in 90 days and over 25 inches! I have came off of my BP meds. My sugar is running perfect too!! :) I want her to be able to say all that too.
Is it safe for cervical cancer survivors to eat edamame, soy nuts, soy milk or tofu? I am a two time cervical cancer survivor and one time skin cancer survivor who has been advised not to eat any form of soy.
February 25, 2011