Older studies had predicated that soy products were possibly bad for you, particularly women. These studies were often poorly laid out and contained no differentiation between soy products and processed soy. Today, soy has returned to the front of health conscious eating. 

"The majority of recent, high-quality studies, however, have found that unprocessed soy doesn’t increase breast cancer risk, and very high consumption could even offer some protection.
Eating soy could help protect against other types of cancer, too. Findings show that soy consumption may slightly lower the risk for gastrointestinal cancers and have a protective effect in prostate cancer survivors. Eating a high-fiber diet is also tied to lower colon cancer rates, and soy foods like edamame and tempeh both have plenty of roughage."

Read more at Good Housekeeping