Tofu is a complete protein, gluten-free, low in calories. It is a good source of calcium and omega-3 fatty acids. Many brands of tofu are made with GMO soybeans (genetically modified organisms). These have been engineered to resist herbicides and fungi, to tolerate pesticides and provide a longer shelf life. The long-term health implications of this is still unknown. Look for USDA-certified organic tofu products for the purest option. Here's a great article on the health benefits of tofu.