The intake of soy may cause the following:
Phytic acid in soy prohibits mineral absorption. Soy is also naturally high in phytoestrogens which can cause cancer, infertility and thyroid issues. This means you should avoid some of the most common soy staples edamame beans and tofu. The only soy products that are potentially safe due to the length and manor of fermentation are organic tempeh, miso, and natto.
Many packaged foods contain soy products so check labels!