[rosaclinic]

According to Medline Plus, a service of the U.S. National Institutes of Health (NIH), soy is an excellent source of isoflavones. These phytoestrogens, which include the popular menopause remedy genistein, appear to influence estrogen levels within the human body. NIH acknowledges the theoretical use of soy as a breast enhancer, but no clinical studies have evaluated its efficacy.
So its better to use other food products also which are breast enhancers.