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Soy Safety: How to Eat Soy without Fear

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Adding more plants into your diet is one of the successful keys to preventing or fighting cancer, but should one of those plants be soybeans? On the one hand, you know you want to avoid lots of animal protein. On the other hand, you want to make sure you aren’t moving from the proverbial frying pan into the fire when making wise dietary choices.

My name is Kim Dalzell. I’m an author, international speaker, and founder of Cancer Nutrition IQ. Learn about the latest scientific and compiled population study results related to soy, one of the most misunderstood plants. You deserve to feel confident about making decisions related to soy.

At Cancer Nutrition IQ, we know that it can be confusing regarding controversial subjects in nutrition. Eating soy foods like tofu, edamame, and soy milk has been linked to reduced risk of certain cancers, including breast, prostate, and stomach cancer. However, some of you may worry that eating soy might be harmful if you have estrogen-receptor-positive breast cancer. And you probably have hesitated: “Is soy good for me, or is it bad for me?” That’s why we have personalized nutrition plans based on your cancer concern and hormonal status to give you a list of the best foods for you, considering how those foods are processed and impact hormones in the body. More about that in a minute. Right now, let’s dig into the topic of soy.

Does soy cause breast cancer?

Soybeans contain many beneficial nutrients like protein, fiber, and potent plant chemicals that protect our DNA from damage and support our immune system. Some of those plant chemicals, called phytoestrogens, act as weak estrogens. Not everyone is keen on estrogen, and for a good reason. Some studies reveal that when single phytoestrogens are extracted from the rest of the soybean, those plant chemicals exert actions similar to the harmful estrogen and can spur on the growth of some cancers. What adds to the debate about soy is that several studies have found that soy from whole food sources protects us against hormone-driven cancers and has other health benefits. The takeaway message is simple: soy isn’t the concern—the source of the soy is the real problem. When you consume whole food soy like edamame, tofu, and soymilk, you’re eating safe and balanced soy protein. You get unnaturally concentrated plant estrogens when consuming isolated, high-dose phytoestrogens from soy (typically found in capsules and some protein smoothie mixes). That’s where the health benefits start to break down. 

Does soy prevent breast cancer recurrence?

Cancer dietitians often get asked if soy is safe for those with a history of breast cancer. The Shanghai Women’s Health study revealed that a high dietary intake of soy isoflavones lowered recurrence among postmenopausal patients with estrogen-dependent breast cancer (CMAJ, Nov 2010) 

Another way to explain the concept of whole food soy protection is to think about the last time you were fumbling in the dark for your keys trying to open your door. You put in a key, and while it might fit, it doesn’t turn the lock. Whole food soy can get into the receptor but doesn’t activate the cancer process. Because whole food soy phytoestrogens have estrogen structure but not estrogen’s power, they effectively block the receptor and any circulating estrogen from activating the cell. The whole-food form of soy is a powerful ally in fighting cancer. 

Does soy offer other health benefits?

From stronger bones to reduced risk of coronary heart disease, soy has a positive impact on many areas of health. Some studies show that 40 grams of soy per day may improve hot flashes. And anti-aging research revealed that women who supplemented their diet with a drink containing soy isoflavones, and other bioactive compounds like vitamin C, had new collagen formation with reduced facial wrinkles! Contrary to the myths out there, soy is not harmful to peri- or postmenopausal women, and soy doesn’t impact testosterone or estrogen levels in men. So, there should be no worries about growing “man boobs” if you are a male.

While the data is limited, there is intriguing evidence that consuming soy during childhood leads to a significantly decreased risk of developing breast cancer goes way down. Soy also doesn’t have adverse hormonal effects on children or impact their development. Millions of men and women in China, Japan, and other Asian countries have had soy foods in their daily diets from their earliest childhood without harmful side effects. Based on the newest analysis of soy and population studies, plant estrogens can provide a safe, plant-based protein source. Soy, in a whole food form, is a good thing.

There is so much more you can do to help yourself get healthy and fight cancer. Our personalized plans can help you. We even have a breast cancer plan that includes nutritional recommendations based on subtypes, like estrogen receptor-positive or triple-negative breast cancers. Here is how it works: 1- Head over to and answer a few questions that pertain just to you. 2- Take some time to dive into your personalized plan and learn about your powerful focus foods and dietary supplements. 3- Rest assured knowing you have quality nutrition information and advice at your fingertips—all of that for only a $14.95 one-time fee.

You can find additional resources by joining our FB community at CancerNutritionIQ and my YouTube Channel DrKim Cancer Nutrition IQ.

Learn about whole food soy shake options here.

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