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January 19th, 2011
10:28 AM ET
Is soy linked to breast cancer?Every weekday, a CNNHealth expert doctor answers a viewer question. On Wednesdays, it's Dr. Otis Brawley, chief medical officer at the American Cancer Society. Question asked by Curious, Texas One of my neighbors has breast cancer. Her doctor has asked her to completely stop eating soy and its products, including edamame and tofu. My neighbor used to eat tofu at least three times a week before she got breast cancer. Is there a link between soy and breast cancer? Is there a potential that I will get breast cancer because I used to eat edamame? Expert answer Your neighbor's doctor is concerned about estrogenic stimulation, which can cause breast cancer. Some of the most effective breast cancer treatments involve blocking estrogen stimulation. Soy does have estrogens, but I believe a moderate amount of soy in the diet is still a good idea for most people. Within the normal diet there are a number of naturally occurring plant-derived compounds called phytoestrogens. Even green beans, peanuts and dates have some phytoestrogen content, but flaxseed, soy and soy byproducts are especially high in phytoestrogens. These compounds are called phytoestrogens as a group, but you may be more familiar with them when they are also referred to by their categories within the phytoestrogen family - the flavonoids, isoflavones, coumestans or lignans. The phytoestrogens have some pro-estrogenic activity and some anti-estrogenic activity. The concern is that estrogenic stimulation can in some circumstances promote breast cancer development. Within the past few years, we have come to realize that some post-menopausal estrogen replacement therapies increased risk of breast cancer, and as a result more attention is being paid to all forms of estrogen stimulation. Even among the soy products, there are differences in terms of amount of phytoestrogen. One survey of foods found that 100 grams of flaxseed had nearly four times as much phytoestrogen as 100 grams of soybeans; 100 grams of soybeans had three times as much phytoestrogen as 100 grams of tofu, and 33 times as much as 100 grams of soy milk. There is the suggestion that a diet with moderate to high levels of phytoestrogens may decrease risk of cardiovascular disease and prevent osteoporosis. Some population studies also suggest that high phytoestrogen intake might have a preventive effect on breast and endometrial cancers in women, and on prostate cancer in men. The Asian diet is high in soy and this is one of the theories as to why the Asian population has low rates of breast, endometrial, and prostate cancer. While large population studies suggest a benefit from high levels of phytoestrogens in the diet, animal studies have noted that extremely high amounts of phytoestrogens may actually promote breast and uterine cancer growth. There is more certainty that phytoestrogens can disrupt the anti-tumor effect of some drugs used to treat breast cancer. As a result, many physicians recommend that women with breast cancer, or at high risk for breast cancer, reduce the amount of phytoestrogen in their diet. Even more physicians do not consider high doses of phytoestrogen safe for women being treated for breast cancer with hormonal therapies (the estrogen receptor blockers or the aromatase inhibitors). For the person who is at average risk of breast cancer, dose is the key issue in the answer to your question. There is a difference between high levels of phytoestrogens in the diet and the very high doses in dietary supplements. It is very reasonable for a person at average risk of breast cancer to eat a moderate amount of soy products, such as tofu, soy butter, soy nuts, and soy burgers, as part of an overall well-rounded healthy diet. While moderate consumption of soy-based products is very reasonable, some supplements extremely high in phytoestrogens, especially soy-based isoflavone compounds and flaxseed based lignans, have been promoted as "natural" treatments for hot flashes and other menopausal symptoms. Very well-designed clinical trials show these supplements are no more effective than placebo (sugar pills) at relieving these symptoms. There is good science to suggest these high dose supplements may have negative health effects.
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Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love. Recent Comments
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What about those at high risk for breast cancer? It's in my family.
As the article indicates, the data is inconclusive. Human population studies indicate that soy consumption as part of a healthy diet lowers the risk of cancer, including breast cancer. However, there are animal studies linking high doses of phytoestrogen (in the form of supplements), and other estrogen replacements, increases the risk of breast cancer. These can also interfere with some drugs used to treat breast cancer.
My take on the article, for what it is worth, is that you shouldn't worry too much about including soy products as part of a healthy diet. The exception to this would be if you are already under treatment for existing cancer (in which case there may be concerns about drug interaction issues depending on the treatment you are undergoing and you should discuss this with your doctor). However, women should, especially if there is a family history of cancer, also do much more extensive research than a CNN article will provide on the subject before taking any high level phytoestrogen supplements or, for that matter, any kind of estrogen replacement therapy including those recommended by a doctor for menopause or post menopause.
Soy Phyto-Estrogens do mimic regular estrogen in their structure but there is a key difference. They resemble estrogen but don't exactly match estrogen. Phyto-estrogens can bind to hormone receptors found in estrogen sensitive cells (ie. breast cancer cells). The important difference is that although they can bind to the hormone receptor, they don't fit the receptor very well. Since this is a "weak binding", the signal that the bound hormone receptor sends to the cell to activate, is a very weak signal. (as opposed to a very strong activation signal that normal estrogen would send)
Soy in modest doses can actually have an anti-estrogenic effect on these cells, as it binds to the hormone receptors and block the stronger estrogen from binding to them, hence lessening the overall estrogen effect on estrogen responsive cells.
If you're interested in great articles about breast cancer treatment and prevention, take a look at http://breastcancerbydrruddy.com/.
Yes, soy is linked to breast cancer. There is much controversy in the breast cancer world about the consumption of soy proteins. As much as I would like to think that this study's conclusions mean it is safe to consume soy products, I still have many unanswered questions... for more-
http://bit.ly/gJo6hV
David Emerson
Do men need to worry about this? THere is breast cancer (from women) in my family.
Women are at much greater risk, but breast cancer has occured in males. After all, males have breasts too.
yes gynecomastia in males too much estrogen
Soy may or may not be linked with breast cancer. Red meat, on the other hand, is linked to 80% of all breast cancer. But the Meat and Dairy Farmers Association lobby Congress far more than cancer foundations do, so any link between red meat and what makes you sick is not forthcoming.
Aloha,
Well said
Don't know where you got that about red meat, because it isn't proven, or at least there is no clear indication of that. The mere possibility of anything concerning your diet is so far down on the list of possible breast cancer causes as to be insignificant at this time.
However, as this article states there is a clear link between breast cancer and estrogen levels and soy contains estrogen. That is the same reason that other factors like menopause, later life child birth and even possibly abortions are heightened risk factors: they all cause increased estrogen levels.
c
Todd A: Pull your head out because it IS proven that OUR red meat in America causes cancer. Why? Because we inject our cows with endless drugs and other chemicals. Have you visited a commercial farm? They are disgusting. The cows have all sorts of diseases, udders down to the ground and are severely malnourished. They feed them ground up cows! You would literally throw up if you knew what large scale farms are doing to the animals.
We need to go back to basics with small local farmers. That is why I support our local farmers markets that are 10 times healthier AND ten times tastier.
Sorry Dana, IT IS NOT PROVEN. There is very strong speculation and indicators, but that is it. You must have a different definition of proof. Not everyone who eats red meant gets cancer, however in ALL cases of breast cancer, heightened levels of estrogen have been discovered. Coincidence?
Not only that, but your "argument" in contradictory. You're saying that red meat cause cancer? But only if it's from a large farm? Eating beef from a small, local farmer doesn't cause cancer?
Why don't YOU pull your head out.
This is disgusting, I present facts and I get flack for it. Nice job!
Dana, US ranches do not feed cows "ground up cows." It is illegal to do so since it is linked to mad cow desease. I live in Texas and have been surrounded by cattle ranches and feed lots most of my life. I have yet to see a bunch of sick cattle with udders hanging to the ground being prepared for the meat market. While I do not appreciate feed lots, where cattle are crowded, fed a corn diet, and live among heeps of manure, thus creating quite a stench, the cows still appear healthy. A sick cow makes no money and the cattle industry is money driven.
Because cows are milked late into their cycle of pregnancy in the west, when they have higher estrogen, there are studies on the link between cancers and dairy milk. http://harvardmagazine.com/2007/05/modern-milk.html When so much of your beef comes from dairy cows, you have to wonder if that also has an impact on the meat or not.
This is garbage. People have been eating soy forever. It is far better than cow's milk and so the dairy council is racing against the clock because people are drinking more healthier varieties like almond, rice, and soy milk instead of drinking antibiotics and pus from cow's.
On one level I agree with you, but there are a lot of soy products that are genetically modified that aren't great for you either. i remember after breastfeeding and starting my son on formula he was having some digestive problems, so my ped suggested soy, it was even worse. I went back to the formula for 3 months – he was 9 months and barely drinking any, but when he was one year, i gave him goat's milk and now I give him organic rice, almond, goat, etc. I think some of the baby formula out there is made with substandard ingredients and wouldn't use it on my child unless it was non-gmo. Just my personal opinion
I remember when only crooked ranchers drugged their cattle to make them fat. Then this crookery became legal! Now most all of them do it, legally! And as if this situation is even being argued about anyway. We could always drag a few more MLB players in front of Congress for doing it to themselves. And where are the animal right's activists concerning this?
I'm not surprised anything that taste as bad as tofu and soy milk has to be bad for you. Yuk!!!
Funny thing about red meat. Isn't organically grown bison meat is different from factory farmed beef?
I don't think all red meat is the same in that case.
Agreed to some extent but I believe a correlation was found between red meat and colon cancer. Also charred meat has carcinogens in it, as well as hot dogs/processed meat. I think an association was found with eating a lot of hot dogs and leukemia in children.
I also wonder if they link venison into that same catagory. I eat far more wild free range venison than beef.
If they are linking soy products as tofu to this my concern is SOY FORMULA..Baby formula. I had to raise 2 of my 4 kids on soy formula. One continued on to soy milk after age of one till she was almost 3. What are the concerns with baby formula and regular soy milk?
I have breast cancer and moderately high cholesterol. I have been adding 2 TB of ground flaxseed to my diet, per day, for a couple of years. I take Tamoxifen (an anti-estrogen drug). I knew I should avoid soy but I didn't know, until this article, that I should avoid flaxseed, as well. Do you think I've done myself harm with 2 TB a day ? What is considered a high amount ?
I'm 52 and I do a 1/4 cup of flaxseed for breakfast every morning. my cholesterol is gorgeous and the anti-inflamitory effects have kept me off motrin for 5 years (2- 800 mg pills daily for 10 years before the flaxseed). I also still have my period, am regular and have no idea what a hot flash is. the rest of my diet is also "good", balanced and heavy on the vegies & whole grains, light on the animal products and processed foods. I have no intention of stopping something that works so well, in so many ways. As for this panic that the article has ignited, get a grip ladies and do some homework. While you are at it, look up omega 3 & omega 6 fatty acids and see what they do. Omega 6 causes inflammation and blood clots and can be found in corn and other winter grains. Omega 3 thins the blood, reduces inflammation and is found in wild fish, greens, and flaxseed. as far as I am concerned, the benefits for me far outweigh any risk factor.
i found out i have fox den diease. i would like to know more about it, my doctor said it is fatal, how long will i live is there other people with it is it possible to be able to talk to one. ive searched on line and i cant seem to find anyone, i was told it was like finding an albino zebra you dont. im scared. ive lost both legs to this and they just cut a 5inch square chunk out of my arm about 1/2 inch deep to remove more tunneling. im homeless and alone i need someone to talk to with it. i have a sister i havent seen in 26 years, we talk as much as possible i have a safelink phone, she my best friend but shes not rich and lives in alaska as i live in florida, i want to be with her and her husband and kids before i die but fate is keeping us apart. do i have time before i die from this disase to be with my sis, my best friend or not. its tough living out side as a paraplegic and now im out side with a wound vac attached to my arm. its lonly and cold and yes as a man im really scared. is there anyone out there like me. please advise. thank you very much larry bon sincerly yours.
Hi Larry,
I had never heard of the disease that you describe until I came across your posting so I went to the web to find out more. It's medical name seems to be called "hidradenitis suppurativa" Here are some websites that you can read about it:
http://hs-usa.org/hidradenitis_suppurativa.html
http://dermnetnz.org/acne/hidradenitis-suppurativa.html
Also here are some websites of support groups and people that have this disease. There seems to be quite a number of people afflicted with this.
http://www.mdjunction.com/hidradenitis-suppurativa
http://www.dailystrength.org/c/Hidradenitis-Suppurativa/support-group
http://www.experienceproject.com/groups/Have-Hidradenitis-Suppurativa/36845
http://health.dir.groups.yahoo.com/dir/1600842889
http://www.angelfire.com/amiga/hssg/
http://community.livejournal.com/hs_support
I'm sorry that I am not of more help but I can hear your upset and pain in your post. Please know that I will be praying for you and I will tell others to pray for you as well. This is a very difficult world right now and the prospects of it getting worse are on the horizon. The only thing we can do is get as close to Lord as we can and trusting him that he will prepare us a place where there will be no more suffering like this. This world has been under the control of a enemy of God for thousands of years but we are promised that the Lord will return to take his children home. I live with that hope in my heart.
Your friend in Christ,
Lyn
Alcohol causes to much estrogen,.. I hope they advise people not to drink who have a family history of BC..
FWIW, The forms of traditional soy consumed in Asia have very little to do with the forms of soy that food companies put into "modern" western diet. Some of the most common forms of soy products consumed in Asia required the soybeans to be fermented over periods of months to ultimately produce the final product - be it soy sause or bean paste. All those of which, have *nothing* to do with the chemically seperated and processed soy ingredients that are so heavily laiden in our food. I would love to see a study comparing the health effects of industrially created soy products vs it's traditional forms.
I highly suspect that industrial "soy protein" probably has a fair number of fewer benefits compared it's traditionally created cousin. I say this out of common sense and being a person who loves dishes such as "doenjang jiggae" but could live without the "texturized soy protein" meat extender addictive.
Very true that major brands do give out samples on their products, search online for "123 Get Samples" we just got ours today. You wont need CC.
Soy is in everything, it's difficult to avoid it unless you do all of your cooking at home.
But I wonder, if the reason Asians have such low rates of cancer due to eating soy, perhaps because they are genetically predisposed to utilize the phytoestrogens in soy? Soy is relatively new to the Western diet, whereas Asians have been consuming it for centuries. Plus, Asians do not eat as much soy and soy products as Westerners tend to do. A bowl of edamame every day, maybe, but eating edamame along with tofu, soy burgers, soymilk and god knows what other soy-fortified and meat-replacement foods? I don't think so.
This was a very interesting answer, though it does not appear to mention some of the most recent research on soy and breast cancer.
A 2009 study published in JAMA reported that consuming more than 15 grams of soy per day decreased the risk for breast cancer recurrence by 32% and decreased the risk for overall mortality by 29% compared to breast cancer survivors consuming less than 5 grams of soy protein per day. One of the most interesting aspects of this study was that the benefits of eating soy were present even in women taking tamoxifen. (Shu XO, et alJAMA 2009; 302(22):2437-2433)
Other studies have reported that …
Doses of soy isoflavones as high as 80 and 120 mg per day did not increase mammographic breast density, a well-known risk factor for breast cancer, in post-menopausal women. (Maskarinec G, et al. Journal of Nutrition 2009; 139(5):981-986)
Pre-menopausal women who consumed more than 13 grams of soy protein per day or more than 44 mg soy isoflavones from food per day had more than a 50% reduction in breast cancer risk. Consuming more than 13 grams of soy protein per day as a teen reduced pre-menopausal breast cancer risk by 43%. (Lee SA, et al. American Journal of Clinical Nutrition 2009; 89:1920-1926)
Postmenopausal breast cancer patients consuming more than 42 mg soy isoflavones per day had 33% reduction in breast cancer recurrence compared to breast cancer patients consuming less than 15 mg soy isoflavones per day. Interestingly, this beneficial effect was also observed in patents being treated with anastrozole, an aromatase inhibitor. (Kang X, et al. Canadian Medical Association Journal 2010; 182(17):1857-1862)
High doses of soy isoflavones (80 and 120 mg) consumed daily for 2 years had no adverse effects. The study investigators reported that all clinical chemistry values remained within the normal range during the 2-year study. Furthermore, this study demonstrated that daily consumption of soy isoflavones at these doses did not affect thyroxine levels, endometrial thickness or uterine fibroids. (Steinberg FM, et al. American Journal of Clinical Nutrition 2010. doi: 10.3945/ajcn.110.008359)
When I Realized Soy Milk was causing stones in my left kidney I stopped taking it. Result no more stones. Back in the past Soy was not used in foods as it is so toxic it was only used in paint and paint thinners.
regarding the person connecting kidney stone with consuming soy -did a doctor diagnose the cause of the stone as soy because I find that hard to believe. too much calcium can cause kidney stones but SOY? what kind of tests did you have before & after you said no more stones (what time-frame -?)
regarding the person on Tamoxofen- I am on a cancer support group (I am cancer free from rare uterine cancer) & a few of the women developed uterine cancer years later after taking this drug for their breast cancer...try to research the connection between Tamoxofen & uterine/ovarian cancer. You may want to discontinue it -
my oncologist recommended NOT consuming soy products -I had been drinking soy milk but switched to almond (great cancer preventor/almonds) also he said do not take flax seeds during chemo but can have flax seed OIL which you add to plain organic yogurt or cottage cheese as a way to get oxygen into the cells & prevent cancer (Budwig protocol – combining oil & protein -CC & FSO
re: soy milk fed to babies & young children. Jethro Kloss began promoting & making soy products back in the 30s (book: "Back to Eden" -a classic bible for simple down to earth timeless advice on nutrition) but I've read that babies &children should not be consuming soy milk. However, I never drank milk even as a child as it produces mucus & not good for adults.
Apparently, in Asian countries the consumption of soy begins at a very early age. Problems, such as soy contributing to breast cancer, possibly arise for those who start consuming soy products when they are older. Soy products should absolutely be avoided should a woman develop and recover from breast cancer that is estrogen sensitive.
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In summary, in this population-based prospective study, we found that soy food intake is safe and was associated with lower mortality and recurrence among breast cancer patients. The association of soy food intake with mortality and recurrence appears to follow a linear dose-response pattern until soy food intake reached 11 g/d of soy protein; no additional benefits on mortality and recurrence were observed with higher intakes of soy food. This study suggests that moderate soy food intake is safe and potentially beneficial for women with breast cancer.
JAMA
This is in reference to the soy supplement by one a day named Healthy Woman. Will this supplement be adequate to take without causing effects of breast cancer.
Thank you.
I've been intensively reading about the link between soy and breast cancer for quite a long time. It all started off with the purpose that I wanted to increase the size of my breast and have fairer skin color. I am an Asian.
So I've been drinking a glass of soymilk morning and evening plus a venti size of Starbucks greentea latte in soymilk for about 6 years. I've never missed this routine for one day. Note that I stick to non GM soymilk.
Several years ago I developed cysts in my breast so I started having mammagram test regularly. I'm told that the cysts in my breast are normal and in fact they indicate that my breast are very healthy. I've also have a fertility test recently and all reports showed that my fertility level and productive system are both extremely normal.I'm 38 yo this year.
So from all my health check reports so far at least they tell me that drinking soymilk everyday as a habit does not bring me any risk to breast cancer or infertility. Quite the contrary, it keeps me healthy, if not preventing those two.
As for all the articles and researches I've read over the past so many years on the topic, I think I can almost conclude that soy products (including soymilk, tofu, infermented or fermented) REDUCE risk of breast cancer WHEN you DO NOT have cancer in your body or when there's no history in the family. However, when you ARE diagnosed of breast cancer already, you need to AVOID it. That means, the phytoestrogen in soy products effects differently to women with and without breast cancer. So the key is to know when to consume soy products and when not to, instead of SHOULD we or should we NOT consume it altogether.
Also, the major cause of cancer is too much acid in the body. There're researches saying that increasing alkaline intake can actually cure cancer. So its all about a balance between the two. All foods are simply categorized as either "acid" or "alkaline". You can find many charts on the internet nowadays to find out which foods contain more acid/alkaline. Soy belongs to the alkaline group. Meat in general is very high in acid.
I'm no expert or doctor but I do believe that keeping a balanced and healthy diet is the key to stay away from all diseases including the number 1 killer cancer. And from my very own experience, its perfectly ok to consume soy products. Generally speaking its pros outweigh its cons.
Hi! I got interested in soybean oil as it is an ingredient in GNC Chlorophyll which I have been taking as a breath freshener and deodorant. However, upon learning that soybean oil is in a controversy as a promoter of breast cancer, I have doubts in continuing my intake of GNC Chlorophyll with soybean oil as I have been diagnosed with multiple cysts in both breasts which I am closely monitoring fearing that these might turn malignant. It is quite paradoxical to be taking a supplement which you think will have positive health effects but will later turn against you. Anyone, please advise me in this.
Soy milk is great but i still prefer the old school cows milk since it contains more calcium. ""'
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I used to think soy products and flax were good for my health. I ate tofu, edamame, tempe, and other soy products, and flax seed bread often. When I started experiencing hot flashes, I took the over the counter natural remiedies. I have aunts with breast cancer, but not my mother or older sister. so I considered myself a moderate risk. I was diagnosd with breast cancer in 2010. I'll never use soy anything again, not even soybean oil and I warn my daughter not to use too much of it either. Also, stay away from excess sugar and alcohol.