Yes that's true but everything should be in a balanced diet because even in a vegetarian diet there are products made of milk such as butter,ghee,cheese and many more so if we consume these types of foods also it is very harmful for our health whereas in a non-vegetarian diet fish is very good for health and consuming little red meat is also good so in both there are good&bad effects.
HOPE YOU UNDERSTAND.
I do have AP world history
Im not 100% sure, but i believe it's crop production will increase.