I was recently asked if I have any concerns about soy (thanks for your comment, Teri!), so I thought I'd answer here so everyone will see it. I use tofu and tempeh in some of my recipes, partly because they're great "transitional" foods for new vegans, and also because tofu is a good egg replacer. We don't actually eat all that much soy in our house, and what we do buy is always organic and non-GMO.
There's a lot of controversy about soy, but according to what I've recently read in Main Street Vegan, by Victoria Moran, the science shows us that it's actually a safe and healthy food, unless of course you're allergic to it. Soybeans contain phytoestrogens (phyto means plant), which do not build up in our bodies. Instead they actually block the absorption of some of the estrogen our bodies make naturally, and by attaching to estrogen receptors in our bodies, they take up the space that other foreign "xenoestrogens" (from pesticides, herbicides, and plastics) would like to occupy. Studies are now suggesting that soy foods can actually help us resist estrogen-dependent cancers.
Asian populations who traditionally eat moderate amounts of soy have lower cancer rates than we do in the US. Maybe it's the soy, and maybe it's the minimal amount of animal products they consume. Keep in mind too, that a plant-based diet is the best way to avoid cancer, as well as so many other "common" western society ailments, like obesity, type 2 diabetes, heart disease, arthritis, osteoporosis, and Alzheimer's. Kicking the animal products out of our diets does far more than worrying about a little bit of soy here and there.
Of course soy isn't necessary to a healthy plant-based diet, so if you're not comfortable with it, don't eat it. My feeling is that a moderate serving of soy, a couple of times a week is probably safe, and most likely a good idea. These foods are, however, still technically "processed," so I usually reserve them for "treats." I prefer to make most of our meals with vegetables and fruits, whole grains, legumes, and nuts and seeds.
I hope this helps clear up some of the soy mystery. Maybe we should start doing Tofu Tuesday!
PS - I came across an excellent article by Leo Babauta, defending soy. I think it's a must-read if you're at all uncertain.