Do soy products cause cancer

Do soy products cause cancer

As a breast cancer survivor of almost 15 years (yay!), I have had a very complicated relationship with soy. Most minimally processed organic soy foods are safe and healthy, but a lot has been written about the dark side of soy – specifically the phytoestrogens and soy protein isolates. Soy protein isolates is an ingredient you probably see a lot, and unfortunately so, because it is just chemical crap disguised as food. A new soy study came out and it’s filled with some great news which will help determine whether or not soy products cause cancer.

Before I get to that, I wanted to mention that I have made the choice to keep organic soy in my diet. In my plant-strong kitchen, you’ll find edamame, miso and tofu, which I consume about 2-3 times a week, with the least being tofu, since it is one of the more processed choices of soy.  I don’t have any push-back from my oncologist, who understands that including organic, minimally processed soy in my diet provides me with lots of protein options and more variety overall. 

What’s in soy?

Soy foods are rich in antioxidants, nutrients, protein, phytoestrogens and essential omega-3 fatty acids. Be warned, though, that almost all soy is genetically modified, so please be sure to buy organic and search for that non-GMO label. You need both because the organic label doesn’t guarantee 100% GMO-free food.

Soy protein and omega-3s are important for heart health, keeping your arteries clear and cholesterol low. The phytoestrogens may help to reduce breast cancer risk among premenopausal woman, and soy foods are easy to digest as compared to their processed soy competition.  

An added bonus is the microflora in fermented soy products, such as miso and tempeh, which are your belly’s best friends.

Is soy a good option for me and how much should I eat?

Is minimally-processed organic soy a good option for you? Certainly if it is non-GMO! It’s always good to keep processed foods to a minimum, and with soy, especially so. The soy protein isolate or concentrate is at the top of my AVOID food list.

Soy dogs, soy ice cream, fake meats, faux chicken nuggets and soy cheese all contain processed soy, in addition to a long list of food additives and preservatives. These foods aren’t real, and while they are okay for once-in-awhile, should not be considered a dietary staple. 

The tendency is to stick to processed soy foods because of our protein paranoia. But we know that protein doesn’t need to be the go-to at every meal. Yes, we need protein, but if you are constantly eating a varied, plant-strong diet of beans, seeds, grains, nuts, legumes and vegetables, then you are getting an abundance of protein-rich choices. Soy, then, becomes optional.

Still concerned about protein?

Use the following formula to calculate your daily protein requirement:  Your body weight in pounds, multiplied by .36, which equals the amount of protein in grams you need as a moderately active adult. So for example, a 140 pound person needs about 50 grams of protein per day. 

One cup of lentils = 18 grams of protein
One cup of quinoa = 8 grams of protein
2 tablespoons of almond butter = 7 grams of protein

So it is pretty easy to meet your protein needs without having to eat soy.

What’s the skinny on breast cancer and soy?

Many doctors, including mine, have been on the fence about whether or not breast cancer survivors should consume soy foods. Most of them play it safe and say no.
Soybeans contain weak estrogens, and the concern is that the estrogen-like properties of soy will make cancer cells grow in women who have, or have had breast cancer. The most common type of breast cancer is hormone receptor-positive, and the medical community is worried that high estrogen levels help cancer grow and spread.  So this continues to be a very controversial issue.
The thing though, is that people tend to be more afraid of soy than dairy, which doesn’t have protective phytoestrogens. Dairy also has huge amounts of estrogen – full-fat dairy products have the most estrogen.

The latest study

The Breast Cancer Registry, a National Cancer Institute-funded program, ran a study on soy and breast cancer, results printed in 2017, which include 6,235 American and Canadian breast cancer patients. They collected clinical and other data on participants since 1995. The researchers analyzed this diverse population’s intake of soy, and the results were pretty astounding:

  • Higher survival rates. Eating foods rich in isoflavones, which are the phytoestrogens in soy foods, is associated with overall mortality. Researchers found a 21% decrease in death among women with the highest intake of soy foods. This was mostly true in women with hormone-receptor-negative breast cancer, which is typically the more aggressive kind. 
  • Increasing soy could increase survival rate after a diagnosis. This is the best news of all — that recent diet is important! If you’ve been diagnosed with ER-negative breast cancer, like I was, soy could play a significant role in your survival.  As a matter of fact, even if you never ate soy before, eating it now, the study shows, could improve your survival rates.
  • Soy isn’t only for ER-negative survivors. Research found that soy is also is beneficial for ER-positive, and both users and nonusers of hormone therapy. 

Reap the benefits of prevention

So now that we know that eating soy can help prevent breast cancer in women of all ages, let’s just remember that it can’t just be any type of soy. Highly processed soy products won’t allow us to reap those preventative benefits. The less processed versions, like tempeh, miso, edamame, and tofu are best, and always, always, make sure they are NON-GMO, and organic.

Asian women have the lowest incidence of breast cancer in the world, probably because they ate minimally-processed soy during puberty while breast tissue was forming. Even if you are past puberty, it pays to add unprocessed soy to your diet. By the way, this goes for guys, too. While it is rare for men to get breast cancer, it happens, so don’t be afraid of a little miso or tofu in your soup.

Don’t forget to check with your doctor to make sure they are up on the latest news on soy and breast cancer.

It is your choice, ultimately, but just know that a plant-based diet with minimally-processed soy is very beneficial, and at least according to this study, soy products do not cause cancer.  Yippee!








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10 thoughts on “Do soy products cause cancer”

  • Hello Amy,

    This is very good news! It is so great to hear that soybeans do not cause cancer. A while I often ate soybean products. Then I heard it isn’t as healthy as I thought it was, so I stopped eating soy products.

    After having read your post I am relieved and can add soybeans to my diet again. Thank you for making me aware of looking for the non-GMO label and for the advice to avoid processed soy products if possible.


    • Hi Pernilla! As long as the soy is minimally processed, it is a healthy choice. Just stay away from the processed variety like soy cheese or soy ice cream. Not exactly food. Thanks for writing!

  • What an amazing well written and informative article about Soy products. I really didn’t know how harmful GMO soy actually was. Scary.
    In Norway they use soy in most of their food products, Since I have IBD i have wondered if GMO soy can make my illness worse and be one of the causes behind my flare ups. Sadly not many shops offer organic soy products.
    Thank you for the Informative Article. It was certainly an eye opener for me.


    • Hi Theresa – so sorry to hear about your IBD. Not sure if the GMO soy would make your illness worse, but eating too much processed soy could certainly contribute to that. The processed variety is irritating, and made with lots of chemicals.  Have you tried miso?  It is very soothing, and made from soy, in it’s raw form.  When you make soup, just add a teaspoon of miso paste to the soup after you remove it from the heat source.  OR you can order miso soup in most asian restaurants, although I am not sure about Norway.  Feel good and thanks for writing!

  • Cancer is a scary thing! I need to stay healthy for my family, and this is the one thing that scares me the most. It doesn’t run in the family, but with the unhealthy products on the market today, I can see why some cancers are on the rise. It was good to find out which soy products are the best. I would have though all of them, I definitely learned something today!

    • I’m glad my post was helpful to you! It is easy to eat processed soy, like soy ice cream or soy cheese, but that stuff is just chemicals pretending to be real food. Best to always stick to the real deal. In this case, it’s miso, tofu, edamame. You can’t go wrong! Thanks for writing!

  • This is great information. I love soy! But it was interesting to read about which soy products are good for me and which ones to stay away from. I definitely want to stay healthy, and cancer is scary. I love edamame, and they are a great snack for me. Thanks for all the wonderful information!!

    • Edamame is great stuff — roasted and lightly salted — delicious…! Not exactly low calorie but so healthy…! Stick to soy in it’s natural forms, and you’ll do great. Thanks for writing!

  • Wow! Thank you Amy for such a great explanation Of soy AND how to figure out how much protein I need per day. It’s very helpful and I am inspired to have edamame and quinoa in my salad today!

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