Many people are still believe in "Soy foods has risk of breast cancer" in women.
However, Studies show that a lifelong diet rich in soy foods reduces the risk of breast cancer and Soy contains protein, isoflavones and fiber, all of which provide health benefits.
"It was once thought that soy foods increase the risk of breast cancer. However, eating a moderate amount of soy foods does not increase risk of breast cancer — or other types of cancer."
"High levels of estrogen have been linked to an increased risk of breast cancer. However, food sources of soy don't contain high enough levels of isoflavones to increase the risk of breast cancer."
When you use soy and isoflavone supplement, you can intake high level of isoflavones in once.
"Some studies have suggested a link between soy or isoflavone supplements and an increased risk of breast cancer in women who have a family or personal history of breast cancer or thyroid problems."
I recommend we should take isoflavone regularly from the real food which is Edamame, Tofu, Tempe, Natto, Soy milk, miso ... not from supplement!
Research reference : Mayo Clinic Ktherine Zeratsky, RD, LD