When I was a teacher at an elementary school in the Bronx, I noticed that my students had poor diets. They started off their day with candy from the bodega and walked into class with blue tongues. For lunch, some students would eat the school lunch but many would eat their own lunch- usually some bags of chips and sugary drinks. I became very concerned about the impact of their diet on their moods and their ability to learn. I created a healthy food policy in my classroom and educated my students about nutrition. But one person can only have a limited impact. Now change can happen faster for...