01/11/2025
Soy foods are often misunderstood—especially when it comes to breast cancer.
One common myth is that soy promotes cancer growth because of its phytoestrogens, but here’s the science:
✅ There are two different types of estrogen receptors in our body—alpha and beta receptors.
✅ Soy phytoestrogens preferentially bind to and activate beta receptors, which have an anti-estrogenic effect, inhibiting the growth-promoting effects of actual estrogen. In other words, in some of our tissues, soy may act more like an anti-estrogen.
Where did the outdated myth that soy could increase breast cancer risk come from?
➡️ A study on mice. As it turns out, we are not mice.
What happens in humans?
➡️ The most striking finding is that 90% of breast cancer patients who ate the most soy after diagnosis were still alive five years later, while half of those who ate little to no soy had sadly passed.
➡️ Pooling all the results from more than 10,000 breast cancer patients, researchers found that soy food intake after breast cancer diagnosis is associated with:
✅ reduced mortality (meaning a longer lifespan)
✅ reduced recurrence (less likelihood the cancer comes back)
This improved survival was for women with estrogen-receptor negative tumors and estrogen-receptor positive tumors, as well as younger and older women.
Pass the edamame!
Watch the video “Is Soy Healthy for Breast Cancer Survivors?” at see.nf/soybreast to learn more.
PMID: 21955647, 22631686, 23725149
DOI: 10.1097/NT.0b013e31828fff54
