How much do we understand about nutrition?

Eating food is our most intimate contact with our environment. It is a very intimate contact with our bodies. We eat every day pounds of food, putting food inside our bodies and turning it into us. This is an amazing process that changes our bodies and our health. But really how much do we know about this process? How much attention do we really put into what goes into our bodies? And how much do we understand about what we eat? How much do we understand about nutrition and the dramatic impact nutrition has on our current health and our body shape?