Some women experience pain and bleeding as a result of having fibroids. Fibroids are sensitive to estrogen, meaning that high estrogen levels tend to cause fibroids to grow, and cause more symptoms. In fact, some treatments for fibroids work by blocking the effects of estrogen. So drugs, foods, or supplements that work like estrogen may worsen fibroids.
Some research suggests that phytoestrogens work in complex ways.
They affect some body functions the same way human estrogen does, but they affect other functions differently. We do not yet know how soy affects the uterus and fibroids. Studies in animals suggest that phytoestrogen affects the uterus like estrogen does, and may make fibroids worse. But one study found no changes in the uterine tissue of women who ate a lot of soy. These very different data show that more research is needed in order to know whether phytoestrogens worsen fibroids.