What question is first asked when discussing all things vegetarian? The question about the nutrients; not only protein, but the vitamins and minerals, as well. The title of this post is linked to one of the most well-written, non-preachy, purely informative-without-being-overly-technical pieces I've read about veganism (for the best book of similar nature, try
Becoming Vegan). The author asks a good question; why is it only when vegetarianism is mentioned that people start questioning nutrient intake? Why not, "Oh, you're an omnivore. That's pretty interesting. How do you get your fiber/antioxidants/complex carbohydrates?"
As I'm sure I've hinted at before, I love animals and all that jazz, and the positive impact on the environment is something I notice, but the real reason I became vegan is for health reasons. This is why the above quote from the article fascinated me so much. Thoreau said it in Walden Pond, something to the effect that all animals lower on the food chain build muscles, bones, a healthy nervous system, etc. by eating nothing but a strict vegetarian diet. Nope, they don't even drink their mothers milk once their digestive system is able to handle solid food. Naturally, then, there's no reason we can't do the same (the things that might be argued to set us apart -- our capacity to reason and have moral worth -- are not dependent on anything found by eating the flesh other animals).
The article talks about a couple interesting points, like how the calcium in milk actually must be artificially placed into the cow's diet, as there's no longer room for them to graze in actual pastures where the green, leafy, calcium rich vegetable matter grows. But if you go straight to the source -- eating green, leafy vegetables -- you get all the benefits of the calcium without 1) the puss from overtaxed udders

and 2) the "calcium-leeching animal protein" that accompanies most milk drinkers' daily diets. A second good point made on this issue: imagine, at your age, drinking human breast milk. Even imagine it going through the same pasteurization/processing method used in the dairy industry. Doesn't that still seem odd?
In defense, I know a lot of people just like the taste of a juicy prime-rib, a cut of sirloin, or their 2% on their cereal in the mornings. But I'd wager most people have switched milk types at some point in their lives. Have you ever gone from whole to 2%, or 2% to 1%, or skim? It tastes and "feels" odd for a bit, but after awhile, your old preference is suddenly foreign. What you drank for years just doesn't quite taste right. I found the same thing with Silk. I tried the non-flavored, then the vanilla, and I settled on the Light Vanilla. It's not too thick and has a good flavor to it. It took me a bit (a week or two) to settle into where I wasn't consciously thinking, "this tastes different...oh, that's because I'm drinking bean-juice." One day, just like % did for me years ago, it just became a background for my delicious Kashi Cinnamon Harvest cereal. I found the same thing as I gave up beef, poultry and fish. In fact, what's better, I found out how much I love red bell peppers, field greens, honeydew melons, and Royal Gala apples (and, yes, I did try about 12 other kinds of apples before I found those). Things I never ate prior to my switch don't "fill the void" caused by a lack of meat, but simply take preference in taste to what now seems foreign and (forgive me) grotesque to my senses.
Ok, to wrap up this little vegan rant my friends were probably wise to stop reading after the first quote, let me just say this; as mentioned in the article this post is linked to, I agree with the author that we've become overly obsessed with single nutrients. We obsess over calcium or omega-3, or worry about whether we're getting the right amount or the right kind of proteins. But I don't think there's any such thing as a well-balanced diet. I eat what I'm hungry for, and let me tell you, biting into an artichoke heart unexpectedly in the middle of an Italian salad is pure bliss. I stock my fridge and pantry with good, solid, whole foods and build my meals up from there. And I gotta say, I'm now in the best shape of my life (even considering my highschool swimteam days...TDZ has the picture to prove it).
Anyways, I hope this wasn't too much of a bore, and that you didn't take this as a lecture (or stopped reading before you felt that way). Feel free to leave comments, but know that I don't look down upon anyone just because they like the taste of meat. I've tasted both sides of the debate, and I simply prefer my food the way I do. This was simply meant to dispel a couple myths and answer the question most often asked.
"The point here is to demonstrate that far from being deficient in essential nutrients, plant-based diets are actually brimming with them."