Soy milk is a healthy, eco-friendly alternative to dairy, but it does carry its own health concerns. Because it's highly processed, milk soy can contain plant estrogens that have been linked to a number of female cancers. Furthermore, the cultivation of soybeans is estimated to have destroyed close to 20 percent of the Amazon rain forest in the past 40 years. The take home? Don't rule out unprocessed soy products (tempeh, for instance), and unrefined soy milks, but make sure you know the origin of your soy.