I don't eat things that used to have parents. We were originally all supposed to be herbivores. Fourteen million years ago, the cave men and women that dwelled on the earth didn't have sharp enough canines to cut through meat. In fact, they hadn't even discovered meat, milk, or eggs. But as they began trying to eat meat, their teeth eventually grew sharper and more prominent.
Meat is a very high source of fat, an unnecessary element in a healthy diet.
However, it is also a high source of protein, which is what most vegetarians have trouble with. The omnivore has no cause for worry in the area of protein. They do, however, need to think about their fat intake. Too much fat can ultimately result in cardio-vascular difficulties since the fat builds up around the heart and stifles its movements. They do need to worry that they are getting enough of these things.