Zone4me, in regards to soy, the so-called miracle bean is getting a thrashing on the Internet. Since the 'Net is also host to millions of opinions, conspiracy theories, unsubstantiated rumor, I prefer to find factual data.
I know The Zone officially endorses soy products, and can be applied to a completely vegan lifestyle (as well as to a completely paleolithic diet). I don't mean to contradict Zone science. I eat a bit of soy-based products myself.
The basic fact is that soy is a legume, and all raw legumes contain toxins, and not just trace amounts either. Even raw green beans contain an unsafe level of toxin. Raw lima beans contain strong concentrations of cyanide; dangerous cyanide gas is released when lima beans are boiled. Fava beans can cause [i:92ed8c46f3]favism[/i:92ed8c46f3], a rare blood disease in some people, sometimes leading to fatal acute anemia. (In the wild, there are no animals that eat raw legumes, leading some to believe these poisons are legumes' hidden defense.)
I don't mean to scare you, but the truth is, raw soybeans contain toxins. Millennia ago, over-population (or what anthropologists call intensification) in the Yellow River basin forced the Chinese to use soy as a meat protein substitute because [i:92ed8c46f3]they didn't have any meat[/i:92ed8c46f3].
They didn't say "Mmmm, these soybeans are good. Let's eat them instead of pigs. Imagine the health benefits!" They said, "Dude, we've over-crowded ourselves. There's not enough mushu pork to go around. We gotta eat something or we'll die of starvation. See if you can do something with these soybeans I found." (For the same reasons, Aztecs became cannibals, and Magellan's crew boiled their shoes, but, alas, these crazes never caught on.)
Several experiments followed, probably resulting in disease and death, but they eventually figured out a way to ferment soybeans. This process slowly breaks down the fiber (carbs), isolating the proteins of the bean into the curd paste called [i:92ed8c46f3]tofu[/i:92ed8c46f3]. The traditional way to ferment soybeans is still seen in China, where they soak them in open barrels on rooftops for two years. Two years. The toxins are able to break down and evaporate.
The problem is not with traditional tofu, but with industrially refined soy isoflavones, a modern process which probably does not allow adequate time for soy to lose its toxicity. Modern soybean agriculture also incorporates genetic engineering and chemical pesticide treatments unknown to the ancient Chinese.
Of course for all the anti-soy opinions out there, there are plenty of soy defenders. Indeed, soy seems to be a commercially sound crop that [i:92ed8c46f3]can[/i:92ed8c46f3] be a healthy diet supplement. Its oil is used in ink, candles, cosmetics. A case can be made that, had soy enjoyed today's marketability in the 1930s, American farmers wouldn't have suffered the dust bowl.
And, eaten occasionally, soy is surely less dangerous than most of the crap we put in our mouths.
Personally, I wouldn't eat a vegan diet. I don't eat soy protein powder or soy 'flour', but I'll have the occasional tofu, soy breakfast 'sausage', and protein bars (I prefer bars made primarily with whey-based protein). But I keep it in moderation.
Specific health concerns linked to soy are hormonal: Estrogen and thyroxin seem to be affected. These articles have more info...
These first two are from perhaps the most popular anti-soy website. The first link describes toxicity, the second discusses the thyroid problems associated with soy:
This article seems more opinion, but cites solid supports:
Here's a piece that gets a lot of use: