Soy products are thought to be a factor in the dramatically lower mortality rates from prostate cancer in Japan, as compared to the United States. Traditional soy foods such as tofu, miso, tempeh and soy milk all can be easily incorporated into the diet — play around with some new recipes until you find some that are right for you.
It’s not known whether the same benefit seen in population studies using traditional soy foods also applies to soy extracts containing isoflavones, so I would recommend using the traditional soy foods for now.