There are many MANY studies that prove omnivores have higher risk of cancer, heart disease, diabetes, hormonal imbalances, and basically every illness. The reason for this is not only consuming the meat, but the way the meat was initailly obtained. Your not just eating a hamburger that was once a happy cow that would run around in the open medows until the day it died and became your dinner. Your eating a cow that was grown in a disgusting infested slaughter house filled with diseases and mistreatment. Most of these animals go through the most horrific “torture” so you can get your Big Mac. By tourture I mean how people who work at slaughter houses are not validictorians. They KILL ANIMALS FOR A LIVING. You think they care about the animals?! NO they dont, if you were to visit a slaughter house you would experience the horrific sounds of animals screaming for being scalped alive, most of these animals arn’t paralyzed when they are supposed to be and feel everything that happens to them. Sorry I just thought you should know.

OH YEAH, AND… the next time you go to drink a nice cup of cold refreshing milk, there is blood and pus in it. Yes, there is. Its proven the FDA doesnt deny it. Why do you think they advertise milk so much? It’s because they know if they dont people will realize that they honestly dont need it, and it is just making them fat.

Re. protein:
http://www.veganhealth.org/articles/protein/
or even just http://en.wikipedia.org/wiki/Protein_in_nutrition

Re. environment:
http://www.epa.gov/region07/water/cafo/cafo_impact_environment.htm
http://www.cdc.gov/cafos/about.htm
http://www.ncifap.org/
http://www.fao.org/docrep/010/a0701e/a0701e00.htm

Re. ethics argument:
Premise 1 = Each animal is an individual who deserves the ability to pursue pleasure and avoid pain without unnecessary human interference. Said another way: causing unnecessary suffering is wrong.
Premise 2 = It is not necessary for humans to eat animal products. Eating animal products = causing unnecessary suffering.
Conclusion = Humans should be vegan.

or
If you don’t like premise 1, you can substitute the health or environmental reasons for veganism.

It is very much possible to get cancer/heart disease from excessive consumption of plant-based foods just as it is possible to get cancer from eating excessive amounts of meat but a well-balanced meal will reduce that risk so this is a moot point.

[Tallius, The human body’s design forms strings of “complete” protein from various amino acids acquired through various plant sources.]

That’s partially wrong. You’re on the right track but you got some information mixed up. The human body can produce 10 of the 18 essential amino acids just by synthesizing glucose. The 8 that it can’t produce is covered by consuming either a single source of meat, like eggs for instance, which has all 8 of the amino acids or eating multiple plant sources, as I’ve previously said. And you need multiple plant sources because neither one of them are “complete,” in the sense that any single plant will not give you all 8 of the amino acids, hence the necessity to consume more than one kind of plant to obtain all 8 amino acids. Otherwise, what you just said is an exact mirror of what I just said except with some details mixed up. Good job. You just made a tautology.

[cost to the environment (pollution, habitat destruction).]

Sorry, I’m unclear on this. Can you elaborate how killing animals cause pollution and habitat destruction?

[There is no reason to eat animals, particularly because eating animals comes at great cost: cost to animals (suffering and death)]

Can you elaborate on how the death of a cow is a great cost to humanity? Can you also elaborate on how the suffering of a cow is a great cost to humanity? I’d like to know your personal answers so that I may better address them. I do not wish to make assumptions about your position as a vegan because vegans hold many positions and beliefs. I’d just like to be clear on what you stand on as well as where you stand on various issues.

Veganism isn’t extreme, its just morally consistent. Most people agree it is wrong to needlessly hurt others. Vegans are just a bit more consistent with this basic ethical principle.