Because natural soy foods contain isoflavones, similar to estrogen, some people fear that soy may raise their risk for certain cancers. This is because estrogen is linked to hormonally-sensitive cancers like breast cancer.
But according to the American Cancer Society, when it comes to soy, isoflavones may act like estrogen, but they have anti-estrogen properties as well. Some studies even show that people who ate soy were less likely to get breast cancer.
“The current research does not support avoiding whole soy foods, even for cancer patients or survivors,” McKindley says.
Soybeans, soy nuts and edamame all contain fiber. And a diet high in fiber may lower your risks for several cancers, including colorectal cancer.
Studies among prostate cancer survivors indicate that eating soy foods may lower PSA levels. Among men in various stages of prostate cancer, those who consumed soy milk or isolated soy isoflavones saw their PSA levels rise at a slower rate. The effect was stronger in some men than others, making it unclear whether genetics or metabolism made a difference in lowering PSA levels.