Humans don't need meat for an optimal diet

"Humans have no known anatomical, physiological, or genetic adaptation to meat consumption."
https://www.youtube.com/watch?feature=player_embedded&v=BMOjVYgYaG8
So it is fallacious to assume that we would need meat for an optimal diet.

“It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, and adolescence, and for athletes.” — Academy of Nutrition and Dietetics (formerly the American Dietetic Association)

Have you ever considered this?:

We all claim to care about animals and to regard them as having at least some moral value. We all claim to agree that it’s wrong to inflict “unnecessary” suffering and death on animals and--whatever disagreement we may have about when animal use is necessary—we all agree that the suffering and death of animals cannot be justified by human pleasure, amusement, or convenience. We condemn Michael Vick for dog fighting precisely because we feel strongly that any pleasure that Vick got from this activity could not possibly justify what he did.

So how can we justify the fact that we kill many billions of land animals and fish every year for food? However “humanely” we treat and kill these animals, the amount of animal suffering we cause is staggering. Yet no one maintains that animal foods are necessary for optimal health. Indeed, mounting empirical evidence points to animal foods being detrimental for human health. But however you evaluate that evidence, there can be no serious doubt that we can have excellent health with a vegan diet.

The best justification we have for the unimaginable amount of suffering and death that we impose on animals is that they taste good. We enjoy the taste of animal foods. But how is this any different from Michal Vick claiming that his dog fighting operation was justifiable because he enjoyed watching dogs fight? Vick liked sitting around a pit watching animals fight. We enjoy sitting around the summer barbecue pit roasting the corpses of animals who have had lives and deaths that are as bad, if not worse than, Vick’s dogs. What is the difference between Michael Vick and those of us who eat animal foods?
Quote from an excellent book: http://www.eatlikeyoucarebook.com/