Food glorious food

I am curious...with regards to Food. whta are your thoughts on the following questions: 

1) are we becoming more intolerant to different foods as a society? e.g can't have lactose, gluten, sea food ect
2) have we always been intolerant to these foods but its only now we are finding it out?
3) are we eating so much junk food that we are becoming intolerant?

Are our bodies telling us enough is enough?