It is easier than you think. First, raw and/or dried meat has been in human diets longer than recorded history, so you have to count those. Also, many carnivore

It is easier than you think. First, raw and/or dried meat has been in human diets longer than recorded history, so you have to count those. Also, many carnivores won't eat rotten meat. Next, look at the digestive tracks of pure carnivores and pure herbivores. One is crazy short and the other crazy long. Humans? Right in the middle. Vitamin B12 - absolutely zero natural non-animal sources and B12 anemia can be lethal. Fruit is good, vegetables probably better. Meat in moderation is probably very healthy.